# Subambient full submersion phase change cooled pc



## technogiant

My.......that is a grand title I've given this topic.

Okay first off this is the very early stages of this project, I haven't lifted a dremel or silicone cartridge in anger yet.
It's going to be a very novel project and I'm looking for as much forum participation as possible to make this work out right.....nothing is set in stone and I'd love to get plenty of brain storming going on.

So to set the scene this is a love child between my window ac unit chillbox build which you can find here:-

http://www.overclock.net/t/1264939/helium-results-window-air-con-chill-box-build

and a submersion pc using a fire extinguishing liquid that boils at 34c and so cools the components both liquid cooling and phase change.....there is a nice video of it here:-






The difference being that I'll be using a different fluid...or should I say gas....I'll be using a refrigerant gas that has a boiling point in the vicinity of -16c but using the air con units cooling power to convert that to a liquid in which the computer components are immersed and cooled, the air con unit will also re-condense the evaporated liquid....so hence the name:-

"cryogenic" because it uses substantially sub ambient temps...."2 phase" because the components are both cooled by the liquid temperature and the phase change from liquid to gas when the components are more loaded.....and "submersion" for obvious reasons.

Why am I doing this?....for those that had the strength to read through my original project thread you'll see that I was toying with using different gases in the cooling chamber that would cool more efficiently than air.

It became obvious that using air or any gas as a cooling method was not very efficient at bringing the cooling power of my 3.5KW air con unit adequately to bare on my components....even though I am more than happy with the 5.5ghz overclcock on my 2700k and the relative simplicity/reliability of the build.

Adding an internal water loop to the system would improve the cooling efficiency but adds another layer of complexity and can be prone to failure at these low temperatures.

But I don't just want improved cooling, I want the absolute most efficient form of cooling to take advantage of my air cons power and keep the components as close as possible to the lowest temperature it can maintain , yet still want a simple direct and reliable cooling system and I think submersion phase change cooling fits the bill on all those counts.

Of course its one thing "wanting" and quite another working out how to get there.

I've spent far too much time trying to think around the various problems of doing such a build....most of the problems revolving around how to manage the volume of gas that the liquified refrigerant would create when returned to normal ambient room temperature which expands at a ratio of about 1:240 so the 10 liters or so of fluid required to submerge a mobo and graphics cards would become in excess of 2000 liters.

So I thought how I could reduce the volume of liquid required perhaps by pumping the liquid refrigerant through a loop like it was water or using passive thermosyphones. Both those ideas move away from being the most direct form of cooling that I'd hoped for with the submersion method and add unwanted complexity let alone doubt that they would work in reality.

I had a bit of a eureka moment when I realized the best solution is to maintain the refrigerant in liquid form permanently and so enable me to go with the complete submersion method that I originally wanted because of its efficiency and direct simplicity.

My first thought was that I could simply maintain the required temperature by cycling the air con unit.....but that would mean I'd never be able to open the chamber without losing all the refrigerant.

I need a method of removing the liquid from the chamber whilst keeping it in a liquid form.

One idea is a refrigerant gas recovery pump which could simply pump it into a pressure bottle.....although that would be simple the pumps are very expensive and need relatively frequent servicing.

A better idea and the one I'm favoring the most at the moment is simply transferring the fluid into a container in a domestic freezer which would maintain it in liquid form and then pump it back into the chamber when required.

I'd have the chamber above the freezer unit and simply pump it up into the chamber when required and drain it back afterwards......I'd have to put several safety measures in place to prevent the liquid boiling off in the event of freezer failure or power outages and have an external pressure release vent should the safe guards all fail......but unless anyone has a better idea this is the one I'm favoring currently.

Still that will do for now.....I'd appreciate your views and I'll try and do some sketches to show the idea perhaps better than I've explained it.


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## billbartuska

What's the vapor pressure of the liquid at room temperature?
If it isn't to high, you could just put the computer and evaporator in a pressure vessel (with the appropriate safety considerations implemented).


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## technogiant

Good thought...... but given the size the chamber has to be to accommodate the ac unit evap and the fact it is home made out of acrylic there is no way it would withstand the pressures involved.....when you do the sums even as low a pressure as 1psi amounts to over 250lb force on the larger side panels of my current chamber....no way it would withstand that.

I've not 100% decided on the gas to be used yet, but if its boiling point is in the vicinity of -15c then I'd imagine >100psi would be required to liquify it at room temp.....I haven't the fabrication skills to make a large metal pressure vessel......plus there is no way you would be able to run the many cables that have to exit the chamber through the chamber wall and still have it be able to contain >100psi. ( psu, optical drive, hard disk drive, ssd, monitor, sound system, mouse and keyboard all have to live outside the sub zero environment and be cabled through to the chamber interior).


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## billbartuska

It's all been done before (pretty much everything has!). Perhaps not for the purpose you imagine, but the ideas and techniques are out there.

For example, right there in your compressor housing there are liquid and electrical connections that are ambient on one side and pressurized on the other.


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## technogiant

Don't misunderstand me........I like the idea.......no movement of fluid required....just alternating between internal states of ambient temp at high pressure or low temperature at lower/atmospheric pressure.....one concern I would have though is that some components may suffer damage by going from high to low pressure states....anything that absorbs the refrigerant at high pressure may suffer decompression damage as the pressure drops?........but on the other hand it may not as the temp drop is driving the pressure drop which would prevent explosive decompression, so perhaps thats not actually an issue........yes.....definitely an interesting concept......but you have to know your limitations, the high level of engineering skills and simply the equipment required to achieve such a solution would be beyond me and my budget should I need to get bespoke engineering work done.
I like to think out low tech low budget solutions rather than throw $$$ (I don't have...lol) and high tech at it.......there always is more than one way to skin a cat.

Going back to my concept of a relatively weak chamber operating at atmospheric pressure I do have have a concern about the design and whether it would actually work as I hope.....here is my concern:-

If I was to use a single volatile gas in the chamber with a boiling point of -15c when the chamber temp decreased beyond this level then a negative pressure would be formed in the chamber tending to crush it......I guess the negative pressure would increase the lower the diferential between the chamber temp and normal boiling point of the fluid became.

There in lies a problem, my chamber will not be strong enough to maintain anything but a tiny pressure difference and infact the sealing methods I'm thinking of require the pressure to be balanced with the atmospheric pressure.

A way around this is to include a second background gas in the chamber that is non volatile in the temp range being used, I was considering bottled nitrogen (oxygen free). There would have to be enough background gas to fill the chamber allowing for thermal contraction at the lowest operating temperature.
This setup (together with the expansion/contraction sac outlined in my previous build) would ensure the system never altered from atmospheric pressure.

I'm a little concerned about the use of a background gas though and if it would prevent the system from working....I don't think it would but I'm also aware that non volatile gases are deliberately excluded from heat pipes as the impede their operation..... I think I've also seen the same about 3M Novec 7000 systems being hermetically sealed......not sure if that is to keep the Novec in or the non volatile gases out?

In the one gas system efficient energy exchange will still occur below the "normal" boiling point as the system reaches a balanced equilibrium between chamber pressure/vapor pressure/boiling point/ temperature/ heat load/cooling where by changes in heat load will cause energy exchange and move the equilibrium to a new state.

With my system the equilibrium is broken as the pressure and hence boiling point are fixed, below the fixed boiling point there will be little or no exchange of energy via condensation between liquid and ac unit evaporator, the only energy exchange will be through conduction at the liquid gas interface which will be low or negligible.

So basically the cooling link with my system is broken below the liquids boiling point and would only be reestablished above the boiling point where vapors again condense on the evaporator.

TBH I don't think this is a major problem through, I plan to include a pump to pump the liquid over the evap so that cooling will still occur at sub boiling point (either that or spraying it into the gas phase sort of like bong cooling).
Also I anticipate even in the sub boiling point liquid there will be local hot spots at the cpu/gpu that will generate phase change to gas and take heat to the evap.

So the long and short is although this may be flying in the face of convention a bit I don't think this will break the system....but I'd appreciate other views

Another point I want to pick the communal brain about is pumps.....I want to use submersible self priming pumps to pump the liquid.....I'm thinking I'll use fuel transfer pumps as they are used for diesel and so designed for use with organic type carbon/hydrocarbon chemicals......but I see they all say not to be used with petrol....I guess that's because its more flammable than diesel. I'm not sure what liquid/gas I'll be using yet and may have to resort to butane or isobutane which are of course also flammable. I believe this will be perfectly safe as the internal environment will be oxygen free or at least extremely depleted. These hydrocarbons have an upper flammability concentration limit of about 10% in air above which they will not burn due to lack of oxygen........so if the hydrocarbon concentration is 10% the air concentration is 90% and the oxygen concentration (21% of air) is 18.9% of the total mix.......so basically an oxygen concentration of less than 18.9% will not support combustion of these hydrocarbons.......as I'll be replacing the air with bottled Nitrogen(oxygen free) and as a belt and braces approach using oxygen absorption sachets I really don't think there will be any risk of internal ignition...but again I'd appreciate views of others particularly if they have any expertise in areas such as fuel or lpg pumping transfer.


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## billbartuska

A nitrogen bottle with a pressure regulator set at, say, 0.1 psi.

Hydrocarbon gasses will bite you!


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## technogiant

Quote:


> Originally Posted by *billbartuska*
> 
> A nitrogen bottle with a pressure regulator set at, say, 0.1 psi.
> Hydrocarbon gasses will bite you!


I wasn't actually planning on leaving the the nitrogen line open to the system....just filling and then shutting it off....so there is no need for a pressure regulator on the nitrogen bottle.

"Hydrocarbons gasses will bite you".........yeah......I'm very aware of the potentially catastrophic consequences of using 10 liters of liquified hydrocarbon......and in fact may only use them short term as a cheap proof of concept test before I spend out the £700 on the two 13.6kg cylinders of HFC227ea.

But realistically looking at it from a logical scientific stand point I do not see how there could be a problem, as I stated internally within the system oxygen levels will be too low to sustain combustion. I have thought out a way of sealing the chamber using fluid seals so it will be leak proof, the only way oxygen could enter or hydrocarbon leave would be via diffusion through the materials of the chamber and expansion sac. That would obviously only occur slowly so with the oxygen absorption sachets and regular purging of the system with bottled nitrogen I really don't see where the problem would come from.
But if you or anyone has any thoughts on anything I haven't thought of that may lead to the hydrocarbons biting me please elaborate, that's the reason I'm throwing this open to the forum.


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## technogiant

Uhhhmm........I've just had a thought about how I could contain the liquid more safely between uses with a pressure bottle and without the use of any pumps......pressure bottle at room temp attached to chamber at its lowest point via flexible line, open valve to allow gas into the chamber which liquifies it because of low temps when desired fluid level reached turn off bottle valve and place pressure bottle in freezer.
Bottle pressure will decrease and become lower than atmospheric because of low temps...to return fluid to pressure bottle just open the valve again, low pressure in the bottle and gravity will return fluid to pressure bottle....close valve place pressure bottle in room to bring back to ambient temp for repeat of cycle on next use......

That would remove a lot of the danger associated with having a large volume of liquified refrigerant only being restrained by the freezers temperature......it would be safely in a pressure bottle between uses.

Is it okay to place pressure bottles in temps reached by domestic freezers about -20c?


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## billbartuska

One of these?

http://i21.geccdn.net/site/images/n-picgroup/RIT_95007.jpg

Freezer would be fine.


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## technogiant

It's good to know I can put the pressure bottle in the freezer, I'm not absolutely sure but hopeful that would allow the fluid to be sucked back into it, don't know if anyone can confirm this would work or know of it being done before?......from my stand point its just experimental.

I wouldn't need to use a dedicated recovery bottle......I was just planning on using the bottle the refrigerant was supplied in......but it would be of a similar type, probably a 13.6kg one, not just a one use bottle.


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## technogiant

Okay I've just done 3 sketches which explains in more detail how this system is proposed to operate, again sorry for the sketch quality.

http://imageshack.us/photo/my-images/525/34570084.jpg/

Uploaded with ImageShack.us

The first sketch above illustrates the chamber filling procedure prior to using the computer.

The freezer is off so that the gas bottle is at ambient temps and the contained gas at high pressure.

Line 2 is opened intermittently to allow gas into the chamber which is condensed out by the ac unit to form the liquid gas pool. Once sufficient gas is pooled line 2 is closed and the pc is ready to use.

http://imageshack.us/photo/my-images/11/88305333.jpg/

Uploaded with ImageShack.us

This sketch represents the situation while the pc is being used, both lines to the gas bottle are turned off, there is no interchange between the chamber and gas bottle/freezer.

Cooling is via evaporation of the liquid at the pc components and re condensation of the vapor produced at the ac unit evap....I may additionally pump liquid over the evap to further lower the liquid temp or perhaps spray it into the chilled gas above...sort of "bong cooling" fashion, as this would allow for greater sub boiling point cooling of the liquid.

Also importantly during this phase the freezer is turned on and both lines/valves are closed. This lowers the temp of the gas bottle to below the boiling point of the gas contained in the bottle and so lowers the sealed bottles pressure below atmospheric in readiness to recover the liquid from the chamber.

http://imageshack.us/photo/my-images/11/30964708.jpg/

Uploaded with ImageShack.us

This last sketch shows the turning off process, the pc is turned off, the ac unit re condenses all the refrigerant gas to liquid and then line/valve 1 is opened to the gas bottle.

The chamber is still at atmospheric pressure due to the expansion sac and the fact that the chamber contains sufficient non volatile gas to fill it (from bottled nitrogen).

The gas bottle is however at lower than atmospheric pressure as it is now at a temp lower than the boiling point of the contained refrigerant, so the gas bottle will actively suck a certain amount of the fluid back into the bottle because of the pressure difference.

Hopefully it will suck back all the liquid but if back pressure builds before that occurs I'm quite confident from what limited experimentation I've done that the remainder will drain back via gravity.

I can maximize the suck back by using a larger bottle as a low pressure in a larger bottle will suck back more volume before pressure builds sufficiently to stop the flow.

Also, again from what I've learned through experimentation agitating the bottle and pipe will cause the fluid to flow back by gravity.....It may be that opening line/valve 2 may also assist the pressure in escaping even though they share the same route as they enter the bottle.

Once the liquid is returned to the bottle the valves are closed and the bottle and freezer are allowed to return to ambient ready for the next run.


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## technogiant

*sigh*........getting bored now.....tech news is all pretty static.....bored bored bored.

Gonna have to spend my hard earned on something......so I've been working out exactly what materials I'm going have to order to make a start on this.

So think I'm going to make a start on this now...just trying to find a cheaper source of the HFC 227ea /FM-200....messaging a Chinese supplier on alibaba.com


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## Drewmeister

I like your thermosiphon idea the best so far. Actually it would be a gravity fed heat pipe in this situation. I think if you can keep the inlets to the water blocks/boilers flooded then there won't be any problems with proper vapor return to the condenser.

My suggestion would be to have a self contained AIO(all in one) type system inside the chillbox. It would consist of a thin horizontal condenser above the pc compartment and that will gravity feed the water blocks with liquid refrigerant. Vapor return back up to the top rows of the condenser. The beauty of this system would be that you could use r134a by tuning the pipe for around 9psi/-15c at zero load.

Your latest plan would require a whole rework of the chamber right? I guess the pump would make or break this setup. Any loss of pump at high oc and load could kill your hardware. It would probably have to be a diagram type pump with a float switch.


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## Terrere

I would advise you to look up how a common meat cooler works with the compressor compressing the gas into the liquid form of the coolant and pushing it through the system. It would help you avoid the gas pressure problem because those are completely closed loops with regulators and expansion valves to help balance the liquid to gas pressure ratio.


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## technogiant

Thanks Terrere, I've been looking for links to how a meat cooler system works but not found anything specific as yet....If you could give me a link or elaborate I'd be grateful......I'm always open to new ideas.

Having said that I'm pretty certain I've thought out the process to fill the chamber and recover the liquid now...at least in my mind.

I'd simply use a standard bottle upside-down linked to the chamber by a single pipe bottom filling/emptying from the chamber sump. A freezer would be used to create the pressure differences to move the liquid.

I know your not meant to store pressure cylinders upside-down but as far as I can ascertain that is only because the liquid phase in the bottle would be covering the pressure release valve rather than the gas phase, so if any excess pressure did develop in the bottle then liquid would be ejected from the safety release valve rather than vapor...which obviously once in the open would expand to a much greater volume of gas and be a more significant loss.

Excess pressure is not going to be a problem as the gas bottle is going to be in a freezer and I will ensure it is not overfilled with liquid so there is plenty of vapor space in the bottle.....the majority of the times the bottle will be at negative pressures.

The revised fill and recovery cycle is really quite simple.

From the starting point with the bottle in the freezer obviously first chill the chamber down so you don't get explosive decompression, then remove the bottle from the freezer in and place in an upside-down position allow it to warm so that the bottle pressure starts to build, open the tap valve and the bottle pressure will push the liquid phase which is obviously covering the valve opening along the hose into to chamber sump.
Once filled, close the valve and replace the bottle in the freezer.

The recovery is a little more complicated because of the way the tap valve works, the sealing piston is not directly connected to the valve screw, so I anticipate that when the bottle is under negative pressure that unscrewing the the tap will not release the valve piston as the negative pressure will hold it closed.
So the initial stage of recovery will strangely involve again allowing the bottle to warm to build some pressure and pop the piston seal open, once opened the bottle would again be place upside-down in the freezer this time with the valve open.

In this situation the vapor phase in the bottle would be separated from the vapor in the chamber by the liquid phase in the bottle/hose/chamber sump all of which would be in a continuous "U" shaped bend.

The pressure in the chamber would be at atmospheric due to the expansion sac and the fact that it also contains sufficient volume of non volatile gas to fill the chamber (from bottled nitrogen....well non volatile in the temp range I'm considering....lol) while the pressure in the bottle vapor chamber would be below atmospheric as the temperature would be below the boiling point of the liquid and this vapor phase would only contain volatile vapor (no nitrogen).

So the pressure difference would be equalized by liquid being pushed into the bottle. This of course would then mean that the bottle vapor pressure would become the same as atmospheric, but as the temperature is still below the atmospheric pressures boiling point then vapor would phase change back to liquid so restoring the bottles negative pressure again to below atmospheric. The heat given off by the phase change back to liquid would be absorbed by the freezer and buffering ice packs and this energy would essentially be what is driving the liquid movement.

From an energy consideration standpoint the max volume of vapor that would be needed to re-condense would be 15 liters of vapor which equated to about 63ml of refrigerant liquid, the heat of vaporization per ml of liquid is about 200 joules so a total energy of 12600 joules.....If a freezer can deliver 100w of cooling or 100 joules per sec then it would take just over 2 minutes for this process to occur......in any event the freezer will also contain ice packs that will buffer this energy absorption requirement (and any loss of freezer function at a critical moment which may otherwise prevent liquid recovery).

So as you can see this would be a continuous process that would occur without any back pressure build up until all the liquid is recovered at which point you turn the tap valve off.

The only other problem I can envisage would be if nitrogen were to get into the bottle vapor space, that may affect the bottle pressures....but that would be easily removed just by purging the bottle at the chamber fill stage. Initially rather than having the bottle upside-down just put it the correct way up, the boiling liquid phase would then push the vapor and nitrogen out of the bottle, probably the nitrogen first as it is less dense and would be at the top of the vapor space, once purged like this simply turn upside-down and the liquid will then be pushed out.


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## Terrere

Try this,slide 6, if you are familiar with common cooling setups. You wouldn't need the condenser fan, defrost timer, or anything really to defrost the system since you aren't using Freon or anything to drop it below freezing temps. You are just wanting subambient temps correct? If you use some other coolant all you will need is a compressor and assembly plus the actual lines. Normally with high power compressors you need copper tubing to avoid line pressure issues, but if your compressor doesn't have an extra strong pump you can settle for less rigid line material. You can look at industrial HVAC systems as well for a sample workflow for a compressor style cooling example. Also, if you want to use the least restrictive style vapor/liquid system. This wikipedia article has some good tidbits about vapor compression. Basically, instead of a normal radiator, you use a set of condenser coils, can get these off of an old refrigerator in a junk yard. Hope this helps you see whether or not this is an option. If you have an old AC unit you can make the compressor work for this, I think.

EDIT: Even without freon you will still need condenser and evaporator coils. Just asked a family member who knows the industrial cooling method. He did say that even just a little bit of high level coolant will probably freeze all of your components. So just a word of warning, treat it as Nitrogen or dry ice cooling and insulate all of your components to prevent damage.


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## technogiant

Thanks for those links Terrere, some good info in those.

I'm not really sure what I'm suggesting is covered by traditional refrigeration techniques though. Perhaps I didn't fully explain the setup.....I'm going for substantially sub-ambient temps, I'm currently running a fully sealed and insulated chillbox which consists of a window style ac unit with the evap enclosed in the chillbox and getting temps of -30c to -22c dependent on load, The chillbox contains air to cool the pc components which are also contained within the chill box.

My proposal involves replacing the air with a refrigerant gas that will liquify at those temperatures and so form a pool of liquified refrigerant I can submerge my mobo in.

I'm not considering any further compression/decompression stages, the liquid pool will solely be formed by the temperature within the chillbox which will be below the boiling point of the refrigerant gas.

The pc components will be cooled by direct evaporation of the refrigerant liquid which will be re-condensed in the cold temp of the chillbox caused by the ac units evap.

Much of the discussion above has simply been about how to safely remove the liquified refrigerant from the chamber into a pressure bottle between uses when the chillbox will return to ambient temps, not being a pressure bearing vessel it could not contain the refrigerant liquid which would boil off to form a huge volume of gas.

I think the system I've worked out to recover the liquid to the pressure bottle is actually used within industry and is called "cold line transfer"...so I've probably just reinvented the wheel again...but not being qualified in these subjects I'm just trying to brainstorm my way through as I go.

I'm unsure from your comments if I have made the proposed setup clear or perhaps I've not understood you.


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## Terrere

Quote:


> Originally Posted by *technogiant*
> 
> Thanks for those links Terrere, some good info in those.
> 
> I'm not really sure what I'm suggesting is covered by traditional refrigeration techniques though. Perhaps I didn't fully explain the setup.....I'm going for substantially sub-ambient temps, I'm currently running a fully sealed and insulated chillbox which consists of a window style ac unit with the evap enclosed in the chillbox and getting temps of -30c to -22c dependent on load, The chillbox contains air to cool the pc components which are also contained within the chill box.
> 
> My proposal involves replacing the air with a refrigerant gas that will liquify at those temperatures and so form a pool of liquified refrigerant I can submerge my mobo in.
> 
> I'm not considering any further compression/decompression stages, the liquid pool will solely be formed by the temperature within the chillbox which will be below the boiling point of the refrigerant gas.
> 
> The pc components will be cooled by direct evaporation of the refrigerant liquid which will be re-condensed in the cold temp of the chillbox caused by the ac units evap.
> 
> Much of the discussion above has simply been about how to safely remove the liquified refrigerant from the chamber into a pressure bottle between uses when the chillbox will return to ambient temps, not being a pressure bearing vessel it could not contain the refrigerant liquid which would boil off to form a huge volume of gas.
> 
> I think the system I've worked out to recover the liquid to the pressure bottle is actually used within industry and is called "cold line transfer"...so I've probably just reinvented the wheel again...but not being qualified in these subjects I'm just trying to brainstorm my way through as I go.
> 
> I'm unsure from your comments if I have made the proposed setup clear or perhaps I've not understood you.


I misunderstood your intentions.







It's fine, I now get that you aren't looking for a subambient cooling system to create a component contained loop.







After rereading your posts, I see that I just took the wrong impression from the initial post and it more or less "biased" my other readings. I will be watching to see how this turns out.









BTW you have a self-contained version of what I was meaning.







The air conditioner does the compression, condensing, and evaporation methods of the coolant for you.


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## technogiant

No problem Terrere.....I've changed my mind and considered so many different methods while thinking this one out I've confused everyone ....including myself....lol

But now I've thought out what I believe to be a fool proof way of recovering the liquid refrigerant I'm confident to go ahead with my favored method which is the full submersion one.

It eliminates many of the problems of the other methods I've considered and the only real drawback was the large volume of liquid refrigerant it would require....which I'm now sure I can safely contain.

Thanks for your input anyway Terrere....please feel free if you think of anything else.


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## technogiant

Quote:


> Originally Posted by *Terrere*
> 
> BTW you have a self-contained version of what I was meaning.
> 
> 
> 
> 
> 
> 
> 
> The air conditioner does the compression, condensing, and evaporation methods of the coolant for you.


Absolutely correct........the additional stuff I'm trying to work out is really just a method of delivering that cooling power as directly, effectively, simply and reliably as I possibly can to my pc components.


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## Terrere

Quote:


> Originally Posted by *technogiant*
> 
> No problem Terrere.....I've changed my mind and considered so many different methods while thinking this one out I've confused everyone ....including myself....lol
> 
> But now I've thought out what I believe to be a fool proof way of recovering the liquid refrigerant I'm confident to go ahead with my favored method which is the full submersion one.
> 
> It eliminates many of the problems of the other methods I've considered and the only real drawback was the large volume of liquid refrigerant it would require....which I'm now sure I can safely contain.
> 
> Thanks for your input anyway Terrere....please feel free if you think of anything else.


Yeah, I'll be tracking the thread and if I have any input that can be of use I will gladly share!
Quote:


> Originally Posted by *technogiant*
> 
> Absolutely correct........the additional stuff I'm trying to work out is really just a method of delivering that cooling power as directly, effectively, simply and reliably as I possibly can to my pc components.










I finally realized what you were actually using the AC for and then it all made sense! I think it's a pretty solid design to me, but my experience on cooling systems is more closely linked to industrial solutions.







I definitely will watch to see what comes of this idea!


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## feznz

Cool idea just one problem I can fore see the sealed chamber will have to withstand huge pressures as the liquid will expand to gas.
I cannot tell you exactly how much but I believe it would be 100 times the volume of liquid at a very minimum but could be as high as 45,000, liquid to gas volume.

that's if you had the expansion sack or what ever attached it would have to be the size of a house to equalize the pressure other wise I can see a potential for a huge pressure spike. Before the evaporator started to condense the vapor.
I would put a 1bar safety valve vented to out side your house to be on the safe side. you can always top up the liquid bath later when the system has equalized and running.

I would probably also look at having a pressure chamber for the motherboard chamber. but you also have to remember that under pressure, liquids will change their boiling point to .a higher temp.

I like your idea I would love to run my pc at -25 on load every day too


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## technogiant

Cheers Feznz.......You are right about the huge volume and pressures that would involved. The average volume ratio for refrigerants liquids to gas volumes is 1:240....so my 15 liters of liquid refrigerant would become 3600 liters or 3.6 cubic meters. The pressure to contain the gas at ambient temps would be in the vicinity of 100psi.

Don't worry my expansion sac isn't that big and I'm not expecting my chamber to go above normal atmospheric pressure...lol

Much of the above discussion has been about how to transfer liquified refrigerant from my computer chamber into a pressure bearing gas bottle. You see while in the chamber the temperature of -25c will maintain the refrigerant as liquid even at normal atmospheric pressure as its boiling point is about -15c.

The liquid will be transferred to the pressure bottle while still cold and in liquid form at atmospheric pressure by the process I've outlined...which I believe is known in industry as "cold line transfer"

Also when the liquid is transferred back from the bottle to the chamber as it will have been in the freezer (temp about -20c)the bottle pressure will be sub atmospheric and will only build slowly as the bottle warms and will then force the liquified refrigerant (not gaseous) slowly into the chamber.

So my chamber will not be at high pressure and the huge gas volume will always be just 15 liters of cold liquid.

The only time I'll be emptying bottle pressure gas into the chamber will be when I initially load it with refrigerant...and yes that will have to be done progressively in pulses that the expansion sac and condensing rate of the chamber can deal with...from a power stand point it will probably take the 3.6kw ac unit about 15 mins to condense out 15 liters of refrigerant......but once that is done it will remain in liquid form apart from the boil off from the pc components during use which I'm sure the 3.6kw ac unit and 250 liter expansion sac will cope with.

Ps...I'm already running my pc in a chamber at -25c 24/7 with air cooled components...so it can be done...this is just going to be a vast improvement over air in the way the cooling is delivered and bring my load temps right down.


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## feznz

I had a look at your previous a/c build and basically limited to the air medium to transfer the heat from CPU to evaporator hence the liquid medium.

I think it is a brilliant idea I am keen to see work









I just believe the balloon may prove useless in this case as to condense the gas back to liquid you will have to also get the balloon cold enough to condense the gas to liquid again.

I believe holding the refrigerant under pressure in the cold box may be the solution hence safety valve to replace the balloon. with sufficient expansion volume within the cold box.

I can see this is going to be a tedious filling operation but once up and running I am keen to see the results









This is pure speculation but I will keep an eye on this thread


----------



## technogiant

Thanks Feznz, I understand your thought process about containing it in a pressure vessel. But tbh once you go down that route the engineering requirements increase exponentially.

My aim has been to make the system as effective as possible but still within my limited DIY capabilities so I'm trying to design the system to remain at or near atmospheric pressures.

Again I understand your thoughts about about the balloon, but it will not require cooling in itself. Very much as it works now with my current build, while chilling the chamber down the chamber air contracts and causes a pressure drop which then makes the balloon empty into the chamber, the same pressure drop will occur with the new build when refrigerant gas phase changes back to liquid at the evap so the balloon will empty back into the chamber where the contents would be chilled causing more contraction and further discharge from the balloon into the chamber.....it's a continuous process so there is no need to chill the balloon.

I think I will see a larger difference in the volume change in the balloon when comparing the idle to full load conditions with this set up due to the large volume changes that occur with phase change as opposed to just the volume change caused by the difference in chamber temp I see now when going from -30 at idle to -22 at full load.....but I don't see this as something that will be in constant flux rapidly going from balloon full to balloon empty and back again as the chamber itself will have quite a bit of "heat buffering" effect as the components are submerged in a substantial quantity of liquid and for a given heat load it will just reach a steady state volume.
If there were to be large, rapid and continual volume changes that would be a problem as it would effectively transport a lot of heat into the chamber as the balloon isn't thermally insulated, also the balloon would become too cold and affect its flexibility perhaps causing it to crack......I don't see this happening though as I anticipate a steady state volume will be achieved.

This is how I anticipate it will work; as well as the refrigerant liquid/gas (RG) the chamber will also contain a background gas (BG) that will not liquify at the temperatures being used. This is required to maintain the pressure at atmospheric as if it only contained RG then below the boiling point the chamber pressure would be below atmospheric and be crushed.

I'd have sufficient volume of BG so that at the lowest idle chamber temperature the expansion sac would be about empty. So if we consider the volume of the chamber, the vapor space, to be about 100 liters and the largest volume of the expansion sac to be 250 liters then at the coldest idle temps there would be 100 liters of gas the majority of which would be BG and a small proportion being RG say for the sake of argument 99% BG 1% RG.

As heat load is applied obviously the quantity of BG will remain the same but it would be possible for the proportion of RG to increase until the expansion sac was filled.

In those circumstances the new total volume of the system would be 100 + 250 = 350 liters and the fraction/percentage of RG would be 250/350 or 71% RG and 29% BG.

So basically the RG composition could theoretically increase from 1% to 71%.......If you think of this in terms of water vapor and humidity....obviously the higher the humidity the easier and more likely it is that water vapor will condense out.

So I envisage that as the composition of the vapor changes and becomes more saturated with RG the more easily the system will be able to re condense it and a balance point will be reached dependent on the heat load, % saturation and the chambers cooling ability.

But yes I concede that at this point I have no means of telling where the balance point would be but do believe a potential 71% RG vapor content would be sufficient to allow efficient re-condensation. Of course this balance point will also be dependent on the balance of heat load and cooling power.....which again is loaded in favor of success with a 3.6kw ac unit doing the cooling.

But yes granted this part is conjecture/educated guessing at this time.....and time will tell









+++++++++++++

Something further I've just considered as relevant to this discussion is the efficiency of the transfer of heat energy to the evap. I think that this process will actually become more efficient as the heat load increases.

If you consider the situation at lower heat load, as the small volume of RG boils off it will hit the much larger body of BG which will be at substantially below the RG's boiling point (the lowest idle chamber temp I've hit is -33c with my current build). So I anticipate it will directly re-condense in the chambers vapor before it hits the evap. This will of course warm the BG that will then be cooled by the evap.....but as you can see at this stage the transfer of heat energy to the evap will be via the BG being cooled as it hits the evap or a gas/evap energy exchange.

At higher heat loads as the proportion of RG saturation increases I envisage that a greater proportion of the RG will be directly re-condensed on the evap surface and so at this point the heat transfer to the evap will be via phase change which will be so much more efficient than a gas/evap energy exchange.

So if the gas/evap interface ever was the limiting factor in terms of chamber temperature in my current build I see this phase change/evap interface being much more efficient and may well lead to lower loaded chamber temperatures which vary with my current build from about -30c idle to -22c at load, I guesstimate the max load atm with my current components to be around 500w - 600w.


----------



## Drewmeister

It looks like you have this all worked out pretty good. Hopefully you can find a cheap dual port recovery bottle with the larger 1/2" ftgs. The recovery bottles have a dip tube on the highside so no need to turn bottle upside down.

The heat pipe system that I mentioned before would be separate and completely sealed from the chamber. It's basically a stand alone Gravity Fed Heat Pipe System. See drawing. The gas condenses in the radiator and drains down to the cpu/gpu boiler chamber where it pools and boils off.. the superheated gas rises up back to radiator where it's cooled/condensed.

The piping is large diameter as to not impeded flow in either direction. The cpu/gpu boiler chamber has large volume for capacity. The base would be a boiler enhancement plate for achieving lower core temps. Charge port is soldered to the radiator, all joints can be soldered as pressure is only 80-100psi tops if using r134a.

Anyways.. just throwing some ideas out there.

Any Updates?


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## technogiant

Thanks Drew......Yeah I have put a lot of thought into this....probably too much thought and not enough action......but your right....I feel I've thought this through to a point it's feasible to start.

I do like the thermosiphon idea, its nice and "contained". I think the main issue would be getting sufficient liquid flow to return while venting the something like 750 -1000 ml/sec of vapor generated at full load in the opposite direction...as you say you would have to have as wide a bore pipe as possible.

I tried a simple experiment blowing through a pipe connected to the bottom of a water filled container raised above me, even when blowing quite gently not a bit of water back flowed into my mouth...just a simple experiment but shows the potential problems. Even using wide bore pipes these would have to narrow down at the opening to the boiling chamber if I was to use standard water blocks as the boiling chambers....other than that it would involve custom boiling chamber builds.

The other problem that arises is that you would not just have one boiling chamber, but one for each gpu and the cpu. If you were to just use one condenser for all of them then you could potentially have "boil off balance " problems where one chamber would become over filled with liquid and the other under filled.

That could be over come by having one condenser for each boiling chamber...but that increases build complexity/cost

The other alternative would be to have the multiple boiling chamber linked by a bottom tube so the liquid levels between them would equalize.

But this in itself poses problems in that even with the mobo mounted flat the gpu boiler/s would be higher than the cpu boiler, so to have the gpu chamber filled to a sufficient level then the fluid level in the cpu boiler would actually extend into the pipes above and perhaps restrict gas boil off. I'm not sure this would cause a problem as the gas would force through anyway.

The outcome of this is that you would have to have quite a bit of liquid to fill the cpu chamber and pipes above to the level of the gpu, the bottom connecting pipe and the gpu chambers.

I wouldn't be containing this under pressure as you've indicated in the diagram, I'd be allowing it to return to ambient and boil off and be contained in an expansion chamber with the aim of using standard pc rads, water blocks and piping. I think that making pressure bearing rads, custom blocks and pressure piping would be a step too far for my skills. So the problem for me is the amount of liquid needed may be too much to contain in gaseous form. So for me this and the fact that standard water block ports may be too restrictive make it a less desirable option.

But if you have the skills to make a pressure system as per your diagram but just with an interconnecting bottom pipe between the multiple chambers then this would be an effective simple and reliable option.

Tbh the full submersion option has none of these potential problems, it allows for almost nude die cooling with the addition of the highly conductive graphite diamond dust heat spreader I've thought of. The heat spreader can be almost any size I desire and not constrained by the size of a boiler chamber, the build is basically so simple with no concerns about fluid return or venting capacity and just requires circulatory fans to operate it...perhaps two pumps just to cause fluid circulation and enhance the cooling efficiency.

Now I'm satisfied I've thought out how to recover the fluid to a pressure bottle I'm decided on the full submersion method.

That's great info about the dip tube on the recovery bottle though, that would be just perfect for my needs...don't have any links to that sort of thing do you Drew?

As regards updates....still all talk no action at this time....I've decided to do this in an out house/shed rather than in the house...which I have to build first...making preparations to do that currently so hopefully build will be starting in a month or so....the sooner the better for me...getting frustrated at not being able to start straight off.


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## wsjackson5

This idea makes me very excited. I knew submersion cooling wasn't just scifi/mineral oil. I look forward to seeing how this goes.


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## technogiant

Thanks WSJ......I'm just starting to get some things together for this build now.......I've been thinking how to make the containment of the liquid in the chamber while being used as safe as possible. I was thinking of making my own submersion sump out of acrylic sheet so I could get just the size I wanted but found this pressed stainless steel container which is the perfect size.....being seamless one piece construction and made of steel there is no chance of leakage or fracture.

http://www.clickonstore.net/stainless-gastronorm-200mm-deep-23rds-size-p-258.html

The pipe to fill and drain it will no longer enter via a hole at the bottom as I want to maintain the integrity of the bowl....it will enter from above and be placed so the pipe opens at the bottom of the metal container....as it fills by pressure and drains by suction it will still function properly.....so this metal basin will form the submersion sump and be enclosed in a chamber made of acrylic that will contain the gaseous phase.....it's not going to be a pretty build, that's not really my thing, I'm more interested in function, so a cooking pot will do me fine....lol

Going to use a flexible stainless steel pipe to run from the stainless steel basin to the pressure bottle...that's going to be the next purchase..can get these here:-

http://www.southdownsmotorcaravans.co.uk/pdf/sdmc_gaslow_centre_stainless_steel_hoses_brochure.pdf

Being stainless steel it should last about 20 years and not split or crack at low temp...but I'll also be putting a second wider bore pipe over that as a belt and braces approach so if the first pipe were to leak then the liquid would just flow back into the freezer through the second pipe where it would be maintained as a liquid and not explosively boil off, I could then vent it off safely in a controlled manner.

I've been putting some more thought to the fluid traps I'll be using to seal the chamber and have been trying to think of a good liquid to use. As the gases I'm using are non polar and hydrophobic in nature then the best would be water...except I don't want it freezing and ice expansion potentially causing damage. Trouble is I can't use standard anti freezes such as glycols or methanol as the gases are soluble to some extent in them which could lead the liquid seals actually becoming a bridge for the gases to diffuse through and escape.

So I've been looking for an ionic solute to use, normal salt, sodium chloride came to mind first...but that is only good down to -23c......there best candidate I've come across so far is calcium chloride, a 30% by mass solution with water has a freezing point of -50c so that's more than enough for my needs and being ionic in nature will deter any gas solubility. And more importantly its readily available.

http://www.reagent.co.uk/calcium-chloride?utm_source=googlebase&utm_medium=free&utm_campaign=googlebase&gclid=CNiL3LfOs7YCFRTMtAodzBsAfQ

It won't pose any corrosion problems as the only materials touching it will be plastics also I'm going to pour a layer of oil over the top of the water in the liquid traps to prevent water evaporating into the chamber and causing condensation problems....may even use an oil that freezes....something like ground nut oil that freezes at +3c so that it will freeze solid and actually bond the lid on when in use.

Other than the calcium chloride solution...which I would hate to drip onto my mobo as that could be an instant kill I've been thinking of using a saturated simple sugar solution like "syrup"....that is polar and so should not allow the gas to dissolve.....it becomes very viscous and eventually forms a "glass" when cold enough that again would seal the lid on solidly.


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## technogiant

I'm getting some stuff together now, I've got the metal drain pan

http://imageshack.us/photo/my-images/211/sam1251.jpg/

Uploaded with ImageShack.us

The pic above shows my old x38 socket 775 atx mobo for size comparison.
The basin is described as a 20 liter capacity. Its 15cm deep so should be sufficient to cover the tallest graphics cards.

There is plenty of room on the right for cabling and on the left is room for two D5 pumps.

I may even use some in fill material to occupy some of the unused space so I'm anticipating that with the volume occupied with everything in there the actual fluid volume will be reduced to 15 liters or less.

I've also got some things for a more substantial expansion chamber, the hopper ball I used previously was a little too flimsy for containing flamable gas for my liking, also it was greasy in texture, probably as the material is heavily laden with plasticizers which may have been extracted by the gas and contaminate my components, also it may allow the gases to diffuse out.

So I'm going for a different setup for the expansion chamber with these items.

http://imageshack.us/photo/my-images/841/sam1252v.jpg/

Uploaded with ImageShack.us

The breather pipe will enter the upturned green water butt through it's base and the black tray will be filled with water. I'm going to cut down the water butt so that it is 15cm taller than the black tray. the water butt will be stuck to the bottom of the tray by its edge with a small gap separating them to allow water to flow in and out of the butt.

In fact the water level will be the same in the tray and the butt. The breather pipe will lead to the computer chamber and so any expansion or contraction of the gas phase will either push water out from or suck water into the upturned butt while not allowing gaseous exchange with the atmosphere.

I'm hoping that the setup will allow for sufficient expansion contraction but its not something I can really gauge until the system is up and running, it should cope with 50-60 liters of volume change.

To prevent water evaporating and entering the pc chamber through the breather I'm going to cover the water surface with a layer of oil...either mineral oil or just vegetable oil, it will float on top and I think stop the water evaporating into the chamber. I can't use all oil as the gases are soluble in it and would diffuse out through it so the water has to be there to maintain the seal.


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## technogiant

Hi again all and sorry for the silence on this....I considered it time to shut up and get on with things.....so I've been busy doing the list of domestic chores my wife had written that must be done before this project, I've finished those and I'm just putting the final touches to the shed /outhouse I've been building to house this project.

So in all I'm finally ready to start building this project.

After much indecision and basically sound boarding various approaches you will be I'm sure more than pleased that the final design is now decided.

The chamber is going to be very much like a large vapor chamber, the mobo will be fully submerged in the working fluid of liquified refrigerant gas contained in a pressed steel basin at the base of the chamber. The air con evaporator will sit above the steel basin and fans will circulate the vapor phase which will re-condense on the ac unit evap and drip back into the working fluid basin.

The chamber itself will be completely sealed and so as the vapors condense to liquid due to the cooling effect of the ac unit then the pressure in the chamber will decrease.

The lower pressure within the chamber will lower the boiling point of the refrigerant gas.

So in effect the liquid and vapor phases will be in a state of thermal/pressure equilibrium. This has the advantage that regardless of the refrigerants boiling point under standard temperatures and pressures, in this system the refrigerant will constantly be right at its boiling point so that any heat input will cause phase change to gas.

As a consequence of the low pressure operation which will be at it's lowest -10psi compared to atmospheric then the chamber and seals have to be of robust construction able to withstand considerable compressive forces.

The system will not however be required to contain the liquified gas between uses. The pressures involved to do this would be too high to safely work with. So it is my intention to drain the fluid into a pressure bottle between uses, placing the pressure bottle in a freezer will cause low pressures within it which will suck the working fluid out of the chamber and into the bottle whilst still in the liquid phase where it can be contained safely.

So that's the outline of the final design and I'm ready to start building.

I intend to make the chamber out of heavy gauge aluminium either 1cm or 1.5cm thick, the plates of the chamber will interlock in such a manner as that they will resist compressive forces.

I do however need to include some way of viewing what is happening inside the chamber so that I can monitor the working fluid levels and fan operation.

I was considering mounting a usb camera inside the chamber but not sure if it would operate in the low pressure low temp environment.

Alternatively I was considering cutting out a section of the chamber wall and overlaying it with thick plate glass which could withstand the pressure.
***************
Not sure which would be the best means of doing this and would appreciate opinions.
***************

Another area of indecision I'm having is regards component heat sinks.....please bare with me on this as it is a little involved.

To start with as this system uses phase change cooling the heat sink has to have a surface which encourages the conversion of liquid to gas correctly called nucleation.

From information I've gleaned from Novec 7000 builds which also involve submersion phase change cooling then a surface coated with sub 10 micron particles forms the best nucleation surface.

To achieve this I'm considering coating the heatsink surface with Gallium (melting point 29c) and embedding diamond dust in this grit size 2k - 3k.

************
again any info or opinion on this is welcomed
************

An addition problem with submersion phase change is the heat density of the components. Again referring to info from Novec builds the maximum heat density that can be coped with is 6 - 10 Watts/cm^2.

Beyond this point the layer of gas generated at the component surface starts to insulate the component.

So projecting this to the real world the area of my 2700K heat spreader is 3.7cmX3.7cm= 13.7cm^2

So this gives maximum power coolable at the quoted max heat densities of 82watts to 137watts which is too low for an overclocked 2700k.

So I have to increase the area of the heatsink to enable a greater cooling capacity.

Here in lies a problem as I also want to keep the cooling as direct as possible and keep the additional layers to a minimum.

I was originally considering using a layer of panasonic pyrolitic graphite to spread the heat laterally but have some concerns about this.

Although this graphite sheet has a high lateral thermal conductivity, 1700 w/k/m as compared to 400 for copper, the sheet is very thin (25 microns). So considering the total amount of heat that could be transferred laterally through the very thin cross section of this sheet it would in effect be no more than a 0.5mm sheet of copper placed directly on top of the IHS.

I doubt such a thin layer of graphite or copper would actually be able to transfer a sufficient amount of heat energy in a lateral direction to cope with the heat generated.

So I've moved away from the graphite idea.

I'm now thinking of using an Akasa all copper 1U server air cooler heatsink.
I would cut off all the fins as they would only serve to trap bubbles and so insulate the component. So it would leave me with a flat plate of approx 8cmX8cm so even using the lowest heat density figures that would be sufficient to cool 384watts.

Additionally to try to remove as many layers as possible I'm considering removing the center of the heatsink so that it only makes contact with the IHS around it's outer edge...perhaps for a width of 1cm.
So that the IHS will be in direct contact with the working fluid directly over the cores and yet the heat sink will still be able to remove additional heat through the edges to the larger surface area of the heatsink to allow for greater heat dissipation required by the oc'ed component.

I'd also be considering using gallium or gallium alloy as a tim that would be solid under usage conditions as I'm not sure if a normal tim would be washed away by the working fluid.

****************
Again would value views and opinions on this.
****************


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## technogiant

Okay, well I bought myself a cheap webcam to test it out, and the one I have works fine in my current chamber at -24c, so that's a good start, I'd rather include a webcam in the chamber than have to cut a great big viewing portal in the side.
I've no mean of testing this at low pressure in a saturated hydrocarbon vapor at this time but will just have to trust to luck on that.


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## feznz

Awesome I am keeping an eye on this as it is intriguing me


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## technogiant

Thanks Feznz, I think this truly does qualify as a "cooling experiment"...I've certainly never seen any reference to anyone doing anything similar to this, novec 7000 submersion is about the closest but of course that is ambiently cooled and uses liquid not liquified gas....being a first makes things harder as its all going to be trial and error...probably more of the latter....cheers and keep following...if people are interested I'll do a full build log if not I'll just post up results later.


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## deafboy

Subbed...just curious, haha


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## technogiant

And we all know what curiosity did to the cat.........unless of course you're Schrodinger's cat...lol


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## technogiant

Okay guys bare with me on this one, obviously this is going to be a fairly time consuming build as I have to make just about everything myself.
But I have made a decisive start and there is no going back now.

I've stripped the air con unit out of my previous project, man I made that chill box strong so it had to be a fairly destructive tear down and sadly irreversible step.









Still as I now don't own a usable gaming pc it must be full steam ahead.

I've wrestled the ac unit downstairs and into the outhouse/shed I've built to house this project and you can see it below with the cold evaporator rad balanced on top of the pressed steel basin, I've done that so I can measure up the height of chamber I'll need to construct, thats how it's going to be set up with the evap just above the basin both of which are sealed in the chamber.

The chamber is going to be made of 1.5cm alu plate...so now I've got the dimensions it's time to order.









http://imageshack.us/photo/my-images/834/ydsi.jpg/

Uploaded with ImageShack.us

http://imageshack.us/photo/my-images/10/s6cz.jpg/

Uploaded with ImageShack.us

Like I said early days...


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## technogiant

Just ordered my aluminium plate for the chamber.......£380....ouch that hurt....this darn project had better work out now or I'll be spitting feathers.


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## feznz

Quote:


> Originally Posted by *technogiant*
> 
> Just ordered my aluminium plate for the chamber.......£380....ouch that hurt....this darn project had better work out now or I'll be spitting feathers.


I hope it does too







work not hurt I mean
I am a little miffed at how the vapour chamber will be at -10psi, I wait eagerly for some updates


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## technogiant

Quote:


> Originally Posted by *feznz*
> 
> I am a little miffed at how the vapour chamber will be at -10psi, I wait eagerly for some updates


The chamber will have two phases of refrigerant, the liquid phase contained in the steel basin and the vapor phase above which will be 100% refrigerant vapor.

At standard temperatures and pressures the refrigerant has a boiling point of -1c.

So as the air conditioner evap drops the temperature, it can go down to -30c, then the vapor will condense on it, that conversion of vapor to liquid causes a pressure drop as the chamber is sealed (1ml of fluid has a gaseous volume of 240ml). As you lower the pressure then the boiling point of the liquid phase also lowers and would so tend to boil off more readily and so increase pressure.......the whole thing basically is in liquid<>vapor and temperature<>pressure equilibrium.

So the lower the units temperature then the lower the internal pressure and the lower the boiling point of the liquid phase.

You can actually can work out what the chamber pressure will be from a vapor pressure / temp chart as this plots the pressure (boiling off pressure) exerted by a liquid at a given temp.......the vapor pressure exerted by this refrigerant at -30c is about 5psi. Normal atmospheric pressure is about 15psi so the unit will be at -10psi when compared to atmospheric.

That's why I've gone with a substantial chamber build using 15mm alu plate, the chamber has to be large enough to contain the basin and evap so the panels are quite large.....if you work out the force exerted by the atmosphere on those panels at 10psi then there is considerable load present.


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## feznz

On the TIM side I was wondering a will it wash out? maybe not I guess first run will give you an idea but if it does then you could silicone around the socket / heat sink to prevent washout


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## technogiant

I'm not sure if it is a problem or not....don't know if that happens with mineral oil submersion which would be a good parallel comparison?

I'd like to use one of the Gallium alloy based liquid metal TIM's as at the temps I'm hoping for they would be solid not liquid.....and in fact the thermal conductivity of solid gallium is 40 thats twice that of liquid gallium at 20 and most good TIM's are in the region of 10.

That way I'd get the best possible conductivity and no possible wash out problem.

My only concern with the gallium Tims is that a colleague on another site has done an ac unit /water loop build and used these metal TIMs. He has found that their efficiency decreases with use over a fairly short time period of a week or so and he has to do a higher temp remelt cycle to restore their efficiency.

It's an unusual problem and we haven't really got to the bottom of it.

I'm guessing its something to do with different thermal expansion coefficients of the solid gallium and the metal mating surfaces. Pure gallium is a weak metal and breaks like glass (from what I've seen on youtube..lol)....so the stresses caused by the different expansion rates of the metals may be breaking the solid tim.

Another possibility is TIM pump out, gallium expands by 3% on solidification and it may be that during freeze thaw cycles TIM is being pushed out of the joint...although doesn't really explain how a remelt cycle would restore the efficiency.

But like I said, this is just speculation and we're not really sure whats going on there and its putting me off using it a bit.....my chamber is going to have the lid sealed on, and require a gas purge before and after opening, so doing that frequently is not an easy option.

I think my next choice would be arctic silver thermal adhesive....it's a thermal epoxy glue that sets solid...so no wash out ....and has similar thermal properties to normal TIM's.


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## technogiant

.


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## technogiant

?? whats going on with these multiple posts?


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## technogiant

This TIM issue is vexing me a little.....

I think I've decided against gallium/indium alloys....the liquid metal type.....not only because of the degradation issue but also as I'm a little concerned about the interaction with the chamber which is aluminium.....both gallium and indium eat into it...so although unlikely I wouldn't like any of that to washout into the chamber should it become liquid or fragments to break off like pure gallium tends to.

So that only leaves me with arctic silver thermal adhesive.....which is not as thermally conductive and is a one way step and will permanently bond the heat sink to my cpu or heat sink to my gpu.

An alternative I thought of is a little out there but would appreciate views...... Low melting point solder....the indium corporation make an indium/tin alloy solder with a melting point of 118c.

I know it still contains indium but there is no likely hood of reaching the melting point in normal usage and indium remains malleable at low temps and will not tend to break like gallium and maybe gallium alloys would.

They make preforms of the solder and was thinking a shim between the heatsink and cpu IHS and applying heat to the heat sink to melt the shim....not sure if a short burst of 118c would damage the cpu though?

If this was possible then it would have far better thermal conductivity even than liquid metals and would be reversible unlike the adhesive.


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## technogiant

Okay, sorry for the continued sound boarding but I've sorted what I'm going to do with the TIM.

I really want to get the highest thermal conducting TIM that I can.

I've looked into mineral oil submersion systems and just as I thought there is a problem with standard TIM's being washed out by the oil, "Puget systems" solve this by using thermal pads.....but they have a comparatively low thermal conductivity.

I'm not going to risk low temp solder and the liquid metal thermal pad/shims have to be burned in and that may prove problematic with my cooling system.

So despite some concerns about degradation of efficiency and reactions with aluminium I'm going to go with a liquid metal pro.

I'll get one of the alloys with a melting point of 8c so it will in effect go through a remelt cycle every time the the system is left at ambient temps so hopefully the degradation issue won't be a problem.

As regards the reaction of liquid pro /gallium with aluminium.... well I'll just have to be careful......I was thinking that once the heat sink is seated I'd seal around the joint to make sure none comes out......I could use this product....its a liquid PTFE sealant used for sealing pipes and bolt threads and is alright for use with the type of submersion liquid I'll be using.

http://www.toolstation.com/shop/p34357?utm_source=feed&utm_medium=googleshopping&utm_campaign=googleshopping&gclid=CN-EzZ3-sLgCFU3LtAod9woAXA


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## feznz

That's what I had in mind some kind of sealant PTFE based will be best that I am aware of too just a lot more expensive than silicone


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## technogiant

Yeah I can't use silicone, its not compatible with the refrigerant I'm using.

On my previous air cooled chamber build I used "evo stick sticks like" its a new moisture curing polymer based on silane from what I can find out...but cant find out if it's alright with my intended gas/liquid......I've done a limited test leaving a joint in a glass jar full of the gas for a week and the joint remained strong.....but I'm also concerned about long term plasticizer/solvent extraction contaminating the system

I may use the Evo stick and just overlay it with ptfe or epoxy resin is also compatible.....It will be more awkward but I'll get around it somehow.


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## technogiant

Well the aluminium plate has arrived so I've been making a mock up model in polystyrene before I start cutting for real.

On that note I'll probably be using a hack saw unless any one has experience of working with aluminium and can suggest another way? The pate I've got is 1.5cm thick and the code is 5083 "O", I believe the "O" means it's fully annealed so I hope it will be soft enough for me to cut manually at that thickness.

One thing I'm going to have to bare in mind when operating the chamber is the heat capacity of this alu plate.... in all it weighs 62 kilo's!! (I may have gone a bit excessive on the plate thickness, but I'm not an engineer and wanted to ensure it would be strong enough to resist neg 10psi tending to crush it....best too thick than too thin).....alu has a heat capacity of 0.91 j/g/c so to drop 62KG of it by 40c to 50c compared to ambient would take my ac unit rated at 3.6kw cooling power about 12 mins. It's important that I ensure the chamber is fully cooled before I allow the liquid refrigerant in there or I'd get explosive boil off......and I won't be wanting that!!


----------



## Jetskyer

I think your best shot at cutting that thick slab of aluminium is by using a (premium) jigsaw.
You definitely need to be able to control the speed and the amount it 'eats' with every stroke. Normally the blade will go back and forth about 1 cm (as well as up and down of course) which should be tuned back to almost 0. This is called the action of the blade. Cheaper jigsaws don't have any action which sadly enough results in a lot faster wearing blade, so don't set it to exactly 0, it really needs to move just a bit back and forth to keep pressure off the teeth when pushing the blade down.
The speed should be as low as possible, otherwise your blade will burn instantly and won't be able to cut more than 3 cm of aluminum.
In general just let the saw do the work, if you start pushing (because you're in a hurry) you'll burn up the blade as well.
[edit] don't forget to buy a special 'metal' blade, the finer the teeth the better.

By the way, do you have any plans of isolating the whole box as well? I recon with the aluminum being -18 you'll loose a lot of energy because it's effectively cooling your room


----------



## technogiant

Thanks for the advise Jetskyer....I'm going to leave the cutting a while until I've some decent time off to commit to it.

And the insulation....yeah...lol....the alu box will itself be surrounded by an insulation box, I'm going to use 100mm insulation board all around it where that can be accommodated, might be a little tight between the chamber and the ac unit so may have to use 50mm insulation board there.


----------



## technogiant

Okay.....think I've finally found the best choice for the TIM material for my application.

The I've been in contact with the tech department of the indium corporation and they are recommending a product they call "indium heat-spring".

It is a "soft metal alloy" TIM based heavily on Indium alloys.

They are basically a thin soft metal shim that is placed between the cpu IHS and heatsink. They remain in solid form during use so do not wet to the surface but a high clamping pressure...above 40psi is needed which causes the shim to mold to the mating surfaces.
As they do not wet/bond they are not subject to degradation of performance due to thermal expansion "break away", they do not pump out as they remain solid and there is no possibility of contamination of the submersion fluid again as they remain solid.

The only down side is the requirement of a high clamping pressure, the thermal resistance decrease rapidly with increased clamping pressure.....at 40psi the resistance is equivalent to normal TIM and surpasses liquid alloys and solders at 150psi.

Obviously this latter figure would not be attainable but I believe clamping pressure of up to 70psi are possible which would give excellent thermal conductivity.

The big bonus is in their reliability, they have a service life of 5 years and beyond and are apparently tried and tested in industrial/commercial submersion phase change applications although its the first I've heard of them.


----------



## technogiant

Okay.....think I've finally found the best choice for the TIM material for my application.

The I've been in contact with the tech department of the indium corporation and they are recommending a product they call "indium heat-spring".

It is a "soft metal alloy" TIM based heavily on Indium alloys.

They are basically a thin soft metal shim that is placed between the cpu IHS and heatsink. They remain in solid form during use so do not wet to the surface but a high clamping pressure...above 40psi is needed which causes the shim to mold to the mating surfaces.
As they do not wet/bond they are not subject to degradation of performance due to thermal expansion "break away", they do not pump out as they remain solid and there is no possibility of contamination of the submersion fluid again as they remain solid.

The only down side is the requirement of a high clamping pressure, the thermal resistance decrease rapidly with increased clamping pressure.....at 40psi the resistance is equivalent to normal TIM and surpasses liquid alloys and solders at 150psi.

Obviously this latter figure would not be attainable but I believe clamping pressure of up to 70psi are possible which would give excellent thermal conductivity.

The big bonus is in their reliability, they have a service life of 5 years and beyond and are apparently tried and tested in industrial/commercial submersion phase change applications although its the first I've heard of them.


----------



## RnRollie

cool..
since indium is not cheap.. has the Indium corp offered a sample as sponsorship?









Clamping pressure... at 70 PSI core crushing becomes a real possibility you sure you really need a tim?

I mean, if you lap all the way up to toothpaste & silk level; it should be possible to mate ihs & hs to near perfection or at least to a very very good bond


----------



## technogiant

Yeah indium sure is expensive and they sadly made no mention of a promotional/sponsored offer.

A pack of twenty 2 inch X 2 inch Indium shims/heatsprings cost £200!!!

I'd have to go for the 2x2 ones to accommodate the size of whichever gpu I upgrade to.

The price is making me have a bit of a rethink about this.....I only need to increase the IHS surface area slightly in order to obtain the required heat density.

I may just use some thermal epoxy to stick some silver wire/rod directly onto the IHS.....would also cut out a layer in the cooling chain.


----------



## technogiant

Okay call me barking mad if you like....but this forum is dedicated to cooling experiment isn't it.

Thinking I may try and make my own custom TIM to suit my project.

So the problem with normal TIM's is that they are based on grease of some description that would dissolve in my organic non polar submersion fluid as they are similar compounds in nature.....so a possible answer is to make my own TIM using a base that is different to my submersion fluid, a polar suspension medium filled with highly conductive extremely fine particles

First thought I've pulled out of the air for this would be saturated glucose syrup filled with alumina powder.(could throw a little copper sulphate in there as a biocide)

The glucose solution is polar being water based and glucose is also polar, it could actually be a very good medium as at low temps it become like a super viscous liquid so it would not be lost into the submersion fluid because of both its chemical and physical nature and would still "yield" under forces of thermal expansion/contraction.
The alumina would be ideal in that it has high thermal conductivity about 40 w/m/c and also has low electrical conductivity.

Any thought or suggestions on this?


----------



## feznz

Quote:


> Originally Posted by *RnRollie*
> 
> cool..
> since indium is not cheap.. has the Indium corp offered a sample as sponsorship?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Clamping pressure... at 70 PSI core crushing becomes a real possibility you sure you really need a tim?
> 
> I mean, if you lap all the way up to toothpaste & silk level; it should be possible to mate ihs & hs to near perfection or at least to a very very good bond


actually I think you could be onto something here have you ever tried this?
I have seen some old PC before even TIM was thought of.
I wasn't sure what processor you were thinking of but if it were a IVY or Haswell then most people on the cutting edge of cooling run delidded so that would be one less surface to polish and about 1/3 of the cooler surface needed to be in contact.


----------



## technogiant

That may well be a good idea for the cpu, but I'd still be happier having a tiny drop of TIM in there.

Not sure if it is possible to lap the gpu though? I think there may be other components that stand proud of the gpu and prevent you from rubbing it on the grit sheet......not sure??


----------



## feznz

depends on the GPU my Asus GTX 770 DCii definitely doesn't have a heat spreader attached I put mine under water.


----------



## technogiant

Thanks feznz, that certainly looks like bare die to me......wouldn't try lapping that one!!!...lol

I've not much experience of stripping down graphics cards, do they generaly have heat spreaders?... and if so is it normally possible to lap them?


----------



## feznz

to tell you the truth some identical make and model cards are not all the same I have some examples where they decided to use a heat spreader and later on remove them


----------



## RnRollie

in them olden days you could work your way up from 400 grid thru 600, 800, 1200, 2000 upto microfibre + toothpaste, silk + toothpaste ...-and.lots and lots of elbow grease---- on BOTH the CPU ihs and the bottom of the HS/block you could get them both so flat that they stuck together by natural adhesion. In extreme cases you could lift the 1lbs HS/Block up by the CPU.

Nowadays, bow is a bit more of an issue , and it doesn't help that bow requirements for IB & 2011 are different from SB & 1155... but it CAN be mitigated by using a slightly thicker bottom/coldplate and not putting insane pressure on the mounting system









For GPUs lapping is indeed in most cases difficult.
It can be done by riggin up "inverted sanding blocks" , basically blocks of granite of the right dimensions.. But it's only worth it if using an universal GPU block. Its almost impossible to achive for full cover blocks because height differences between GPU, vrm, ram,... (thats why most FCs use thermal pads).
Some FC blocks are better as others... and they can do away with pads and just use minimum paste, because they have closer tolerances..... which is most noticable in your wallet, btw









Of course, if you have some money to burn, you can have your GPU card 3D measured and then have Silver full-cover block milled which fits that specific card perfectly


----------



## technogiant

Thanks guys, you are both a wealth of information.









But I think I need to find a method that is going to work for me regardless of cpu and gpu type.....I'm trying to move away from my current system situation where the build was dictating my component choice.

So I think I'm going to stick with the idea of making a custom TIM suited to my chamber.

I'm going to have to do some experimentation on this but atm I'm considering adding alumina powder or diamond powder to a custom carrier.

Not quite decided yet but I'm looking at a solution of fructose ( a simple highly water soluble sugar) to produce a viscous non freezing medium.

I'm a little concerned about using a water solution as it may dry out over time and it would have to have enough viscosity at ambient temps so as not to run out, particularly on the gpu which will be mounted in an upright position.

An alternative would to use glycerol as the medium....that normally freezes at +17c. I'd have to see what its texture is like when frozen, if it went solid and brittle it would be no good but if it went just sort of viscous or buttery that would be fine. I could even add fructose to it as it is soluble to a degree....about 50g/100ml and that would decrease its melting point and perhaps alter the texture.

It's all stuff I'm going to have to experiment with...but either way it may give better results than commercial TIM as the background carriers in both cases are better thermal conductors than silicone based grease.


----------



## RnRollie

good luck with a custom TIM
i'ld stick to off-the-shelf-albeit-exotic hardly known stuff, or forfeit it all together
after all a TIMs purpose is to cover/fill-in the imperfections between two surfaces; its the overal contact that counts. If you manage to minimise the imperfections of the surfaces, using a TIM might even be counterproductive. TIM is not a magical substance, in the big picture its role/influence should not be more as 2-3%. -> The secret of great engineering is to minimise parts without changing the function of the whole









the thing is, you'ld need to create something that once it is settled retains it properties throughout the whole operating range, is stable and strong even rock-hard but not brittle; as i can imagine that it "failling apart" and thus have (small or large) particles "floating around" is probably not a good idea


----------



## technogiant

Yeah I hear what you're saying there Rollie......I do have reservations about a custom TIM.....much is expected of it over a long period of time.

But I also need a method that is going to work across the board, it may well be that lapping is the answer for the cpu but I also need an answer for the gpu, and with some having bare die and others having heat spreaders that may be awkward to lap...then lapping isn't the complete solution...So I still need an answer for the gpu.... hopefully that answer will also work for the cpu and remove the necessity and work involved in lapping the cpu to a mirror.

I've looked to the exotic and the best I can find is the Indium corp heat-spring soft alloy shims......but at £200 a pack of 20 that smarts a little (as well as the clamping pressure required). But that's a definite plan B atm.

Sometimes I think people endow shop bought / commercial products with a little too much magic......yes they are tried and tested....but an individual prepared to have a go can and frequently does produce better.......lol......in a away that kind of reflects the whole ethos of this project......if I had any sense I'd just go and buy a commercially built phase change unit.....but NO!!!.....I have to build my own experimental design by hand from raw materials in my shed.....lol


----------



## technogiant

Okay.....I know it doesn't look like much.....but what you're seeing here is the result of 2-3 days of cutting by hand with a hack saw









It's the front panel of the chamber measuring 57cm x 53cm and 1.5cm thick.

One down 5 to go :-/

Just wanted to show this is more than a talking shop post and things are genuinely underway.

You can see the tabs and recesses I've cut, each panel of the chamber is going to overlap with the neighboring ones so that under compression each panel will be supported by the others.

Got commitments over the next 4 days now but hope to get back to the hack saw on Friday.....if I've got the strength.

http://imageshack.us/photo/my-images/21/usow.jpg/

Uploaded with ImageShack.us


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## technogiant

Like I said, progress is slow, but I have found an easier way to cut the alu now.....I'm using a jig saw to give an first rather inaccurate cut then grinding back using an angle grinder and metal grinding disc and finally using a hand file to get the more accurate finish.....so hopefully things will progress a little faster now.

I've just completed one edge of the right hand panel, you can see that on it's own below and then together with the front panel......see how the tabs and recesses interlock so each panel of the box will be prevented from being pushed in by the adjoining panels.

http://imageshack.us/photo/my-images/839/ln2g.jpg/

Uploaded with ImageShack.us

http://imageshack.us/photo/my-images/16/xlmd.jpg/

Uploaded with ImageShack.us


----------



## technogiant

I've been putting some more thought to the cpu heatsink and how I'm going to make the sub 10 micron particle surface to enhance nucleation/phase change.

As stated previously I'll be using an all copper u1 server cooler with the fins cut off so I'll have basically a flat evaporator plate.

I was considering using a gallium or a liquid alloy to coat the surface and then sprinkle sub 10 micron alu oxide power over it.......but I've moved away from the liquid metals as gallium will react with the alu chamber and severly weaken it.

So I'm considering just using solder....obviously I'd do this prior to fitting the heatsink.....I'd us flux to promote solder spread out hopefully to cover the entire top side and then sprinkle alu oxide over......not sure if it will be easy to get a large spread out layer of solder though?

Any ideas?


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I've been putting some more thought to the cpu heatsink and how I'm going to make the sub 10 micron particle surface to enhance nucleation/phase change.
> 
> As stated previously I'll be using an all copper u1 server cooler with the fins cut off so I'll have basically a flat evaporator plate.
> 
> I was considering using a gallium or a liquid alloy to coat the surface and then sprinkle sub 10 micron alu oxide power over it.......but I've moved away from the liquid metals as gallium will react with the alu chamber and severly weaken it.
> 
> So I'm considering just using solder....obviously I'd do this prior to fitting the heatsink.....I'd us flux to promote solder spread out hopefully to cover the entire top side and then sprinkle alu oxide over......not sure if it will be easy to get a large spread out layer of solder though?
> 
> Any ideas?


Indigo Xtreme is 100% gallium free, so that's always an option. Of course you could always consider fields metal, though I wonder if that might react with other metals. There's an alloy of fields metal that melts at 44Celcius, so it would basically be a phase change TIM like the IX, though I wonder how well it would transfer heat if temps never exceeded 44Celsius?


----------



## technogiant

Thanks Zythe, they are both very interesting, I didn't realize Indigo EX was gallium free, I may have some problems with the burn in process though the way my system is set up.

I've never heard of "fields metal" before again very interesting.....you may have solved my TIM problem.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Thanks Zythe, they are both very interesting, I didn't realize Indigo EX was gallium free, I may have some problems with the burn in process though the way my system is set up.
> 
> I've never heard of "fields metal" before again very interesting.....you may have solved my TIM problem.


Well here's a link

As for IX you could just burn in the TIM on the heatsink on a test bench before putting it into your mega cooler.


----------



## technogiant

All interesting stuff Zythe......I've just been looking at a video installation guide for the Indigo extreme as I was favoring that.

I noticed that they leave a plastic ETI around the outer edge of the IHS to help contain the alloy during the reflow process...not sure if that would be compatible with my submersion liquid or if I could just cut it away after the reflow installation? I doubt it would be needed after as if I reach throttling temps during normal use with this build something will have gone badly wrong!!

The installation involves running the cpu without any cooling and relying on the thermal throttling of the cpu so that should not be a problem for me to do.

So Indigo Ex seems like a good contender considering it is tried and tested unlike the more obscure alloys.....but of course I'd need to use something else for the graphics processor.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> All interesting stuff Zythe......I've just been looking at a video installation guide for the Indigo extreme as I was favoring that.
> 
> I noticed that they leave a plastic ETI around the outer edge of the IHS to help contain the alloy during the reflow process...not sure if that would be compatible with my submersion liquid or if I could just cut it away after the reflow installation? I doubt it would be needed after as if I reach throttling temps during normal use with this build something will have gone badly wrong!!
> 
> The installation involves running the cpu without any cooling and relying on the thermal throttling of the cpu so that should not be a problem for me to do.
> 
> So Indigo Ex seems like a good contender considering it is tried and tested unlike the more obscure alloys.....but of course I'd need to use something else for the graphics processor.


What dielectric liquid are you using for submersion?


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> What dielectric liquid are you using for submersion?


Liquid Butane


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> Liquid Butane











doesn't that have a big chance of going BANG in case of a leak (+ a flame/spark)?
Not that you'll care, as you'll probably be in a state of euphoria (if not dead) if you didn't notice the leak.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Liquid Butane


 You're using a flammable liquid as an immersion fluid? Be 1,000,000,000% sure there are zero leaks in your rig. You basically have a fancy bomb if you add oxygen.

Pyro 101: There are three things a fire needs to burn: Heat, fuel, and an oxidizer. In order to put a fire out, take one of those out, and vice-versa
Your rig will have two of those, so add oxygen and you have a pretty potent fire, as butane burns pretty hot.

Anyways, back to my point, if the fluid your using has a neutral Ph and no corrosive properties, you could always consider a graphene TIM, by mixing graphene nanopowder with a silicon based thermal grease, then seal the ends of it with a silicon adhesive.

Most dynatron and shin etsu TIMs have a silicon base, so those could be used as the silicon TIM for the mix.

Note: IC Diamond uses a silicon base, so nanopowders in silicon TIM is proven.
Other Note: Graphene is electrically conductive. Do not use it between dissimilar metals.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Liquid Butane


 You're using a flammable liquid as an immersion fluid? Be 1,000,000,000% sure there are zero leaks in your rig. You basically have a fancy bomb if you add oxygen.

Pyro 101: There are three things a fire needs to burn: Heat, fuel, and an oxidizer. In order to put a fire out, take one of those out, and vice-versa
Your rig will have two of those, so add oxygen and you have a pretty potent fire, as butane burns pretty hot.

Anyways, back to my point, if the fluid your using has a neutral Ph and no corrosive properties, you could always consider a graphene TIM, by mixing graphene nanopowder with a silicon based thermal grease, then seal the ends of it with a silicon adhesive. This would be a pretty simple solution for your GPU, and possibly your CPU... well, take away the pretty simple part, but then again nothing about your rig is simple.









Most dynatron and shin etsu TIMs have a silicon base, so those could be used as the silicon TIM for the mix.

Note: IC Diamond uses a silicon base, so nanopowders in silicon TIM is proven.
Other Note: Graphene is electrically conductive. Do not use it between dissimilar metals.
Another Other Note: A brief search shows butane is Ph neutral and has absolutely no corrosive properties.


----------



## feznz

Quote:


> Originally Posted by *RnRollie*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> doesn't that have a big chance of going BANG in case of a leak (+ a flame/spark)?
> Not that you'll care, as you'll probably be in a state of euphoria (if not dead) if you didn't notice the leak.


Just remember every time you drive your fuel injected car the fuel pump is in the fuel tank the only reason there is no fire,
the fuel fumes pushing out the oxygen making it impossible to ignite even if the fuel pump sparks in a short circuit.
fire needs fuel heat and oxygen to survive take one away and it dies.


----------



## ZytheEKS

Quote:


> Originally Posted by *feznz*
> 
> Just remember every time you drive your fuel injected car the fuel pump is in the fuel tank the only reason there is no fire,
> the fuel fumes pushing out the oxygen making it impossible to ignite even if the fuel pump sparks in a short circuit.
> fire needs fuel heat and oxygen to survive take one away and it dies.


His rig will be pressurized... It's essentially a phase change cooler, except instead of using an evap block it uses a large cooling chamber. If it leaks, and there's a spark, or a notable amount of heat you'll basically have a fancy flame thrower. Think butane blowtorch: They have a tank of pressurized butane, and a nozzle. Add a spark and you have a torch. Sound familiar









Now, god forbid, his rig leaks, and gets oxygen in it, you have a fancy bomb.

Butane is fairly stable and has a pretty high auto ignition temp, but still it's something to worry about if you aren't careful.


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> doesn't that have a big chance of going BANG in case of a leak (+ a flame/spark)?
> Not that you'll care, as you'll probably be in a state of euphoria (if not dead) if you didn't notice the leak.


Yes it does.......but I've been researching and thinking out how to do this safely for over a year, brain storming on various forums.......I'm only starting the build now as I'm completely satisfied I've covered all the angles.....and I'm doing this project in a shed not the house in case of un-forseen eventualities.

Leakage of butane out of the system is in fact the least likely problem as the system will be under negative pressure or at maximum atmospheric pressure and can be guarded against by ventilation and a gas detector/alarm

The most concerning problem is leakage of oxygen bearing air into the system as during use it will be under negative pressure, which could lead to an explosive gas mixture within it, but without going into detail I've covered all possible angles of air ingress, even down to tracking in through along the length of the cable sheaths.

Flammable gases have an upper and lower explosive concentration, for butane the upper level is about 10%, above that concentration there is not enough oxygen present for ignition even if an ignition source is present. The gas in the chamber will be close to 100% butane so a long way of from the upper explosive limit. Regular purging will ensure the concentration is kept high.

Also the tendency of the butane to pool at the bottom of the chamber and air rise to the top because of differing density could mean that somewhere between the top and bottom of the chamber could be a gaseous layer of the correct mix for ignition....that layer will be disrupted prior to system start up by starting a fan (brush-less hence spark-less) at the bottom of the chamber that will mix the layers.

I was also concerned about material failure, plastics cracking etc, which is why I've gone for a completely metal, chamber, pressed steel fluid basin (seamless), and flexible stainless steel connection hose which will transfer the liquified butane between the pressure bottle and chamber.

Before loading the system with butane on first assembly it will first be purged using oxygen free nitrogen again to ensure that can be done safely.

So yes you are right......there are potential dangers....as there are driving a car with a tank full of gas....and I'd not encourage anyone to do this without thorough research.....but I'm quite satisfied I've covered all the bases or I wouldn't be doing it.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> *snip*
> 
> The most concerning problem is leakage of oxygen bearing air into the system as *during use it will be under negative pressure*, which could lead to an explosive gas mixture within it, but without going into detail I've covered all possible angles of air ingress, even down to tracking in through along the length of the cable sheaths.
> 
> *snip*


How efficient is a compressor driven phase change cooler under negative pressure? O.O


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> How efficient is a compressor driven phase change cooler under negative pressure? O.O


Well the cooling power is provided by the completely sealed air con unit, the evaporator of which is sealed in the chamber, so the cooling power will not be affected by the pressure in the chamber, in fact it is the cooling effect that is causing the pressure drop.

It's important to keep in mind the system as I've designed it is all about making an efficient way of delivering the cooling power of the air con unit to all the pc components. It does not in itself add to the cooling power but is just an effective and direct way of doing this.

I believe that the heat transfer between the air con evaporator and the gaseous medium will actually be more efficient than just blowing air/gas through the fins. This is because the butane gas will actually be condensing on the fins and delivering its heat energy in a phase change manner.

I've worked out that to utilize the full 3.6KW cooling power of the air con unit would only require it to condense 64 liters of gas per minute which is a tiny amount compared to the 450 cfm my fans can produce.....in fact it may be that the system will not require fans for the cooling process. As the gas condenses to a liquid on the evaporator then more gas will take its place...there can't be a vacuum and the whole thing would be pressure driven, that's basically how heat pipes and vapor chamber work, however I am aware that both of those devices are hindered by the presence of non volatile gases in them which reduces their efficiency, so as I'm not going to be able to guarantee 100% butane content then circulating fans would overcome that problem


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Well the cooling power is provided by the completely sealed air con unit, the evaporator of which is sealed in the chamber, so the cooling power will not be affected by the pressure in the chamber, in fact it is the cooling effect that is causing the pressure drop.
> 
> It's important to keep in mind the system as I've designed it is all about making an efficient way of delivering the cooling power of the air con unit to all the pc components. It does not in itself add to the cooling power but is just an effective and direct way of doing this.
> 
> I believe that the heat transfer between the air con evaporator and the gaseous medium will actually be more efficient than just blowing air/gas through the fins. This is because the butane gas will actually be condensing on the fins and delivering its heat energy in a phase change manner.
> 
> I've worked out that to utilize the full 3.6KW cooling power of the air con unit would only require it to condense 64 liters of gas per minute which is a tiny amount compared to the 450 cfm my fans can produce.....in fact it may be that the system will not require fans for the cooling process. As the gas condenses to a liquid on the evaporator then more gas will take its place...there can't be a vacuum and the whole thing would be pressure driven.


Ah, so the phase change cooler itself will be in an isolated loop from the butane? The steel box itself isn't being used as the evaporator, it will just have the evaporator submerged in the butane coolant. This is making an incredible amount of sense to me.

If that's the case, why don't you use a non-heatpipe cooler with some really powerful brushless fans? You'd have to get better cooling capabilities with an active flow than with just relying on the heat radiation of a copper heatsink.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Ah, so the phase change cooler itself will be in an isolated loop from the butane? The steel box itself isn't being used as the evaporator, it will just have the evaporator submerged in the butane coolant. This is making an incredible amount of sense to me.


Yes the ac unit is isolated and just exchanges heat via its evap. The ac unit evaporator will not be submerged, it will be in the vapor space of the chamber, this is because the pc is being cooled by phase change and it is the vapor that is carrying the heat away and needs to be recondensed.

Quote:


> Originally Posted by *ZytheEKS*
> 
> If that's the case, why don't you use a non-heatpipe cooler with some really powerful brushless fans? You'd have to get better cooling capabilities with an active flow than with just relying on the heat radiation of a copper heatsink.


That would be right if I was just considering conductive liquid cooling.......but the cooling is occurring via phase change of the liquid to gas, the gas generated will simply bubble to the surface and be replaced by more liquid....so there is a passive circulation and no real need for a forced circulation.

The only time that a forced circulation would be required is with heat densities of above 6 to 10 w/cm^2 .....at that point the amount of gas produced starts to insulate the component and a forced flow is required to blow the bubbles away.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> That would be right if I was just considering conductive liquid cooling.......but the cooling is occurring via phase change of the liquid to gas, the gas generated will simply bubble to the surface and be replaced by more liquid....so there is a passive circulation and no real need for a forced circulation.
> 
> The only time that a forced circulation would be required is with heat densities of above 6 to 10 w/cm^2 .....at that point the amount of gas produced starts to insulate the component and a forced flow is required to blow the bubbles away.


A fan could move the fluid at a rate much faster than standard convection could. Wouldn't, in theory, more flowrate result in a lower ΔT between the heatsink and coolant?


----------



## RnRollie

Quote:


> Originally Posted by *feznz*
> 
> Just remember every time you drive your fuel injected car the fuel pump is in the fuel tank the only reason there is no fire,
> the fuel fumes pushing out the oxygen making it impossible to ignite even if the fuel pump sparks in a short circuit.
> fire needs fuel heat and oxygen to survive take one away and it dies.


Fair enough, but these are industrial build, after much huffing'n'puffing by engineers & safety inspectors & and such, not in somebody's garden shed

plus: it makes the fuel difficult to ignite, the fuel fumes however....


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> A fan could move the fluid at a rate much faster than standard convection could. Wouldn't, in theory, more flowrate result in a lower ΔT between the heatsink and coolant?


I see this as being different....although I do understand what you are saying it seems to be more applicable to a conductive liquid cooling model than this phase changing cooling method.

All that is important for this model is that the component is in contact with the liquid that will phase change to gas and that the liquid is at its boiling point being in a pressure<>temperature equilibrium. The liquid temp is not really that important and it will equalize out depending on the balance of heat load and cooling power.

This scenario holds good until critical heat density is reached at 6 -10 w/cm^2 at which point the bubbles prevent the liquid from contacting the component properly.....its at this point that a flow is required but it isn't to ensure a temp delta between the liquid and heat sink but just to physically remove the bubbles so the liquid can make better contact.

In practicality though when you do the maths involving this max heat density and the surface area of the heat sinks then there is no need for a forced flow and they are capable of dealing with several hundred of watts more than required before reaching this heat density. Which is very nice in that it means that this cooling delivery system is basically totally passive, apart from the fans in the vapor space which may or may not be needed.....less complexity is always good


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> Fair enough, but these are industrial build, after much huffing'n'puffing by engineers & safety inspectors & and such, not in somebody's garden shed
> 
> plus: it makes the fuel difficult to ignite, the fuel fumes however....


I understand your concerns Rollie, and as stated I'd not encourage anyone to do this without thorough research as you can see from my brief description I've put a lot of thought into this......but always would welcome any specific thoughts or concerns that highlight angles I may have missed.


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> http://imageshack.us/photo/my-images/16/xlmd.jpg/
> 
> Uploaded with ImageShack.us


i assume you've worked out the pressure differences (both positive & negative) and have dimensioned wall thinkness of your "box" accordingly?
I assume this is the box that'll house the MB & components?

I would feel safer if it were using dovetails and concave walls, or even better : a "bottle" ; but thats just because i've got no idea if you'll have sufficient pressure differences to put a strain on the walls & joints. Most likely its not cold enought to make the Alu go brittle, but i would make 1000% sure that seams are unable to start leaking.

Anyways, this is starting to make more & more sense now... and if you dont turn it into a bomb a fantastic project


----------



## ZytheEKS

Quote:


> Originally Posted by *RnRollie*
> 
> i assume you've worked out the pressure differences (both positive & negative) and have dimensioned wall thinkness of your "box" accordingly?
> I assume this is the box that'll house the MB & components?
> 
> I would feel safer if it were using dovetails and concave walls, or even better : a "bottle" ; but thats just because i've got no idea if you'll have sufficient pressure differences to put a strain on the walls & joints. Most likely its not cold enought to make the Alu go brittle, but i would make 1000% sure that seams are unable to start leaking.
> 
> Anyways, this is starting to make more & more sense now... and if you dont turn it into a bomb a fantastic project


Just be sure to but a sizable chunk of C4 on it so you can blow it up if anything goes wrong, or if you are unsure whether it's all working accordingly.

When in doubt, C4


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> i assume you've worked out the pressure differences (both positive & negative) and have dimensioned wall thinkness of your "box" accordingly?
> I assume this is the box that'll house the MB & components?
> 
> I would feel safer if it were using dovetails and concave walls, or even better : a "bottle" ; but thats just because i've got no idea if you'll have sufficient pressure differences to put a strain on the walls & joints. Most likely its not cold enought to make the Alu go brittle, but i would make 1000% sure that seams are unable to start leaking.
> 
> Anyways, this is starting to make more & more sense now... and if you dont turn it into a bomb a fantastic project


Well the minimum temperature my unit will achieve is about -30c.....at those temps liquid butane has a vapor pressure of about 5psi compared to atmospheric of 15psi so there will be a compressive force on the chamber of about 10psi.

So yes the forces involved will be quite high, at neg 10psi on the largest panel of 54cm by 50cm that works out to 4000lb pressure......I'm not an engineer able to work out the exact thickness of alu would be required to resist that so have gone large....probably larger than required using 1.5cm thick alu plate.

This is something I'm going to do preliminary tests on just cooling the chamber down while it contains just butane gas and is not loaded with the 20 liters of butane liquid that would be required for operation. The pressures inside will be the same regardless.

If it fails at that point then there will be less risk as the butane quantities in comparison will be quite small.

Yes dove tailing with numerous tabs would have spread the load more evenly but I'd have to balance the huge amount of work that would have been involved in that and the possible inaccuracies and gaps that more fiddley work may have caused against the potential gains.

As it is the maximum run of unsupported aluminium plate is 19cm (apart from corner to corner dimensions) and at 1.5cm thick I'm hoping that will be quite strong enough.

If during testing it becomes apparent that it can't withstand those pressures I'll swap out the gas for isobutane, it has a boiling point of -12c compared to -1c for butane and would have a greater vapor pressure at -30c.....so the compressive forces would only be about 4psi using that.


----------



## RnRollie

Quote:


> Originally Posted by *ZytheEKS*
> 
> Just be sure to but a sizable chunk of C4 on it so you can blow it up if anything goes wrong, or if you are unsure whether it's all working accordingly.
> 
> When in doubt, C4


Lolz

I'm a bit concerned (_probably because i dont understand all of the design because i haven't been living inside techno's head







_ ) about the pressure differences because build up in phase change systems can have "undesirable" effects. Think back to the golden age of steam, since turning water into steam is phase change. If the safety features of a steam engine failed, a loud bang was a very likely result, not to mention some death factory workers. Or more recently when Mythbusters closed off all safety valves on a water heater and then set it to boil.
Its just that nobody really understands the power/force of pressure per inch until they have been at the receiving end of a disgruntled woman wielding stiletto heels









So, my question is... the liquid Butane sludges in the box submerging the components ; as it boils off the butane gas "rises" and then gets (re-)condensed by the modified A/C unit. The Butane never leaves the "box".

Now, since butane boils at approx -1 C , what happens if the A/C gives up the ghost and no longer recondenses the butane gas. Forgetting your "hot" components, slowly but surely the ambient temp outside the box will start to radiate in... EVEN if you have your box very well insulated. The butane will continue to boil off until it reaches an equilibrium in the box - too high a pressure to continue to boil.

How you tackle that event? Safety valve? Emergency dry ice drop? I'm curious.

edit: spelling


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> Lolz
> 
> I'm a bit concerned (_probably because i dont understand all of the design because i haven't been living inside techno's head_


lol......believe me you don't want to go there....lol

But yeah the serious side of your post, in the event the ac unit fails.....well firstly there will not be explosive decompression, the systems 62kg of aluminium and 20 liters of butane liquid have a lot of heat buffering potential. But of course heat will slowly ingress through the insulation raising the temp and consequently the pressure.

The chamber has not been designed to contain the butane under pressure and the liquid butane will be transferred back to a pressure bottle between uses and in the event of the ac unit failing the same would be done in those circumstances.

Basically the chamber has a flexible stainless steel pressure hose positioned so that it opens at the bottom of the submersion basin.

The other end of the hose is connected to a standard 15kg butane gas cylinder. The gas cylinder is placed in a freezer at -20c. So the pressure in the gas cylinder is negative as we are below the butane boiling point.

So when the ac unit is turned off (or fails) then the pressure in the chamber will start to increase forcing the liquid butane through the hose and into the pressure bottle.

Obviously as the liquid transfers over then the pressure in the bottle will start to increase, that will cause phase change of the bottles vapor back into fluid so continuing the suction. The heat generated by the bottle vapor phase changing to liquid will be absorbed by the freezer and buffering ice pack so as to continue the suction.

This is a process called cold line transfer and uses nothing but pressure and heat energy to suck/pump the fluid across, so no mechanical failure possible.

The worst case scenario would be a power outage affecting both the ac unit and freezer...but again no problem as the freezer would contain a large quantity of ice that would buffer the heat removal required to suck the liquid from the chamber to the pressure bottle.


----------



## RnRollie

oh yeah, you mentioned cold line xfer before.

Seems like you're going to need some sturdy elements, like for the return line to prevent mishaps & blockages - still a bit of a balancing act, but yeah.. Cool

Its a lot clearer now, cheers , no further questions at this time, yar'onor


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> oh yeah, you mentioned cold line xfer before.
> 
> Seems like you're going to need some sturdy elements, like for the return line to prevent mishaps & blockages - still a bit of a balancing act, but yeah.. Cool
> 
> Its a lot clearer now, cheers , no further questions at this time, yar'onor


Yeah the transfer pipe is flexible stainless steel...so pretty sturdy and not prone to crack at low temps like rubber type hoses....and blockages are the big unknown...trapped water turning to ice...although I'm not anticipating much if any water in there......the other potential blockage is extracted solvents and plasticizers.....but hopefully with an almost all metal build and plastics in contact with the liquid kept to a minimum then that wont happen....if it does and I'm left stuck with a chamber full of liquid butane it will be vented off and burnt away as it evaporates through the purging line.....so although undesirable...not catastrophic.

"balancing act"......well yes the cold line transfer does depend on the balance of pressures between the chamber and gas cylinder....but it's not a precarious balance.....it will progress to completion depending on the temps difference between the cylinder and the chamber....both of which are controllable, in the case of the chamber by either allowing it to return to ambient or cooling it by the ac unit, and the cylinder temp can be controlled by placing it in or removing it from the freezer....so its not a hit and miss affair, the only thing that would stop it would be a pipe blockage but I think that will not be probable.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Well the minimum temperature my unit will achieve is about -30c.....at those temps liquid butane has a vapor pressure of about 5psi compared to atmospheric of 15psi so there will be a compressive force on the chamber of about 10psi.
> 
> So yes the forces involved will be quite high, *at neg 10psi on the largest panel of 54cm by 50cm that works out to 4000lb pressure......I'm not an engineer able to work out the exact thickness of alu would be required to resist that so have gone large....probably larger than required using 1.5cm thick alu plate.*


Worst case scenario you could just grab an oxygen/butane blowtorch and make a steel or iron cage that will be inside the aluminum. As the negative pressure tries to collapse the aluminum, the much stronger iron cage would hold the form. After all, I'm sure you'll have plenty of butane


----------



## ZytheEKS

Double post


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Worst case scenario you could just grab an oxygen/butane blowtorch and make a steel or iron cage that will be inside the aluminum. As the negative pressure tries to collapse the aluminum, the much stronger iron cage would hold the form. After all, I'm sure you'll have plenty of butane


Yeah, I'm not too worried about the way I've constructed the box, ie the single tab design I've used rather than the dovetail that Rollie was suggesting, the problem is not going to be along the edges but at the center of the panels which are unsupported.

It may be a little problematic fitting a cage due to the evap not having much clearance around it but certainly something I could look into should there be a problem.

But really although this is completely subjective just looking at the thickness of the metal plate I've used and the chamber dimensions I just cant envisage it yielding under a pressure of just 2/3rds of an atmosphere......I put 6x that in my bike tire.

PS.....I've been trying to visualize what 10 psi actually means to get some visual handle on it.....I mean when you work out the total as 4000lb on the largest panel that seems colossal.....but of course that load is spread evenly over the entire surface not just in one point.......so I've worked out what depth of water 10psi equates to to get a visual handle on it......it works out to 23 foot depth......good grief that is nothing to worry about


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Yeah, I'm not too worried about the way I've constructed the box, ie the single tab design I've used rather than the dovetail that Rollie was suggesting, the problem is not going to be along the edges but at the center of the panels which are unsupported.
> 
> It may be a little problematic fitting a cage due to the evap not having much clearance around it but certainly something I could look into should there be a problem.
> 
> But really although this is completely subjective just looking at the thickness of the metal plate I've used and the chamber dimensions I just cant envisage it yielding under a pressure of just 2/3rds of an atmosphere......I put 6x that in my bike tire.
> 
> PS.....I've been trying to visualize what 10 psi actually means to get some visual handle on it.....I mean when you work out the total as 4000lb on the largest panel that seems colossal.....but of course that load is spread evenly over the entire surface not just in one point.......so I've worked out what depth of water 10psi equates to to get a visual handle on it......it works out to 23 foot depth......good grief that is nothing to worry about


It's only spread evenly assuming the structure can hold it's shape. Fluid takes the path of least resistance, if the center of one of the walls starts to bow you end up with an unsound structure because as they bow they loose strength, as it looses strength it will bow more . Personally I'm not sure what to think about it, mainly due to the fact that I don't trust aluminum.








Whenever I build a desk, or bench, or anything subject to notable amounts of pressure I've always lived by the ideology "Go big or go home" and when I say that I mean strength wise. I built a desk for my old model RC cars so I could work on them a while ago, and I swear that thing could hold up a small car, so maybe my paranoia is a wee bit bias.


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> Yeah, I'm not too worried about the way I've constructed the box, ie the single tab design I've used rather than the dovetail that Rollie was suggesting, the problem is not going to be along the edges but at the center of the panels which are unsupported.
> 
> It may be a little problematic fitting a cage due to the evap not having much clearance around it but certainly something I could look into should there be a problem.
> 
> But really although this is completely subjective just looking at the thickness of the metal plate I've used and the chamber dimensions I just cant envisage it yielding under a pressure of just 2/3rds of an atmosphere......I put 6x that in my bike tire.
> 
> PS.....I've been trying to visualize what 10 psi actually means to get some visual handle on it.....I mean when you work out the total as 4000lb on the largest panel that seems colossal.....but of course that load is spread evenly over the entire surface not just in one point.......so I've worked out what depth of water 10psi equates to to get a visual handle on it......it works out to 23 foot depth......good grief that is nothing to worry about


The reason for the dovetails is to keep the seams together, when the wall starts bowing, it puts strain on to seams. At some point something has to give: either the wall ruptures, or the seam is ripped apart. In less extreme case, the strain on the seam might be enough to cause a leak... which is not good when working with fluids/gasses that can go boom 

yield depends depends on the type of Alu used.
Are you using pieces of a decomissioned MIG 29 ?









i'ld make a wild guess that your walls of 15mm should be able to stand at least 8000 psi before yielding, unless its 6061, then the rules change
http://en.wikipedia.org/wiki/6061_aluminium_alloy
http://en.wikipedia.org/wiki/Aluminium_alloy
http://www.engineeringtoolbox.com/aluminum-alloy-mechanical-properties-d_1350.html

Actually, for some applications it might be better to use a different alloy to allow for thinner walls with more "stretch" (eg 12%) so they just deform vs thicker, more rigid walls with less stretch (eg 5%) which will go crack when the limit is reached.
Just like different materials , woods are better suited to make a bow or fishing pole vs a support beam or table.

Did you know that the average scuba diving tank is "limited" to 3000 psi ?








Note: that 10 psi = 0.6 atm , which is not nothing








it is what, 6 - 7 meters depth in a swimming pool.. lots of people find the pressure on their eardrums quite uncomfortable at that (shallow) depth. But those are people, not Tin man


----------



## technogiant

Thanks for that Rollie........I didn't fully understand what "dovetailing" meant.....I realize now they are not just tabs but actually tapered to prevent them pulling apart rather than just more smaller straight tabs.

Well granted that would have been much stronger....but probably beyond my DIY skills to do a good and close fitting job though, remember I'm cutting this thick alu plate with hand tools and small non-commercial diy power tools, its tough going.

You've also got to consider how much force will be directed towards separating the joints, I was only considering compression, which will not pull the joint apart but force them closer together, but granted, if the compression gets to the point where panels start bowing and pushing outwards on the joints then that would be a consideration.

But the more I've thought about the pressure and considering those figures you've quoted for alu alloys of many thousands of psi the less I think this is of any concern at all.

Certainly visualizing what that pressure means in terms of depth of water has helped....7 meter / 23 foot.....good grief I could take a lung full of air and dive to that depth without problem, the pressure wouldn't even squeeze the air out of my puny little chest cavity.

Scuba divers easily go way beyond this depth and can still expand their chest against the pressure to breath....this pressure won't bend 15mm alu plate.

So I think in reality this will not be an issue, the thickness of alu I've used is really complete overkill, it wont bow ( or crack, it's a fully annealed alloy 5083 "O"), and so won't put sidewards load on the joints which will be quite strong enough as they are for the forces they will encounter.

But thanks for raising the question Rollie.....it always helps to bash potential problems around


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> It's only spread evenly assuming the structure can hold it's shape. Fluid takes the path of least resistance, if the center of one of the walls starts to bow you end up with an unsound structure because as they bow they loose strength, as it looses strength it will bow more . Personally I'm not sure what to think about it, mainly due to the fact that I don't trust aluminum.
> 
> 
> 
> 
> 
> 
> 
> 
> Whenever I build a desk, or bench, or anything subject to notable amounts of pressure I've always lived by the ideology "Go big or go home" and when I say that I mean strength wise. I built a desk for my old model RC cars so I could work on them a while ago, and I swear that thing could hold up a small car, so maybe my paranoia is a wee bit bias.


Yeah, I did consider getting a custom fabricated/welded steel chamber, but I'm a little cagey in trusting that other people would do a good job and didn't want a chamber that leaked like a sieve. So I decided to do my own and go with aluminium as I thought it would be easier for me to cut. Welding is not an option as I don't have the tools or skills for that so aluminium seemed the best choice.

I also went by your "go large" ethos, I was considering 1cm plate but decided to absorb the extra expense of 1.5cm plating and now as I've mentioned above I think this is actually considerable overkill.

Of course the proof of the pudding and all that......I should be finished cutting out all the panels by the end of the weekend......then I'll run the cables and pipes through the panels before I assemble the chamber. The chamber and ac unit are going to be mounted on a custom platform which I have to make yet, so in all there is quite a bit of work to do....but I'm hoping to complete in the next couple of months.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Yeah, I did consider getting a custom fabricated/welded steel chamber, but *I'm a little cagey in trusting that other people* would do a good job and didn't want a chamber that leaked like a sieve. So I decided to do my own and go with aluminium as I thought it would be easier for me to cut. Welding is not an option as I don't have the tools or skills for that so aluminium seemed the best choice.


It had to be done.

Anyways, I guess I'm just paranoid about trusting aluminum.

Non the less, it'll be exciting to see how low you can get your CPU temps when you essentially have an oversized subzero heatpipe.


----------



## technogiant

lol.....Zythe.....don't know if I got the right meaning of that.....but ya.....I take some shifting if I think my ideas right......lol


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> lol.....Zythe.....don't know if I got the right meaning of that.....but ya.....I take some shifting if I think my ideas right......lol


A heat pipe uses phase change of liquid to gas to move heat. Your chamber does the same thing.







That's all I meant by it.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> A heat pipe uses phase change of liquid to gas to move heat. Your chamber does the same thing.
> 
> 
> 
> 
> 
> 
> 
> That's all I meant by it.


Yeah...its more like a vapor chamber.....so I'm basically building a huge actively cooled vapor chamber with the mobo submerged in the working fluid.

Which is kind of paradoxical......because the reason I'm abandoning my previous air cooled chill box for this new build is because commercial heat pipes and vapor chambers wouldn't work with that system, they contain water as a working fluid which freezes and ceases to function.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Yeah...its more like a vapor chamber.....so I'm basically building a huge actively cooled vapor chamber with the mobo submerged in the working fluid.
> 
> Which is kind of paradoxical......because the reason I'm abandoning my previous air cooled chill box for this new build is because commercial heat pipes and vapor chambers wouldn't work with that system, they contain water as a working fluid which freezes and ceases to function.


I thought most heatpipes used ammonia? Or maybe methanol?
Quote:


> Working fluids are chosen according to the temperatures at which the heat pipe must operate, with examples ranging from liquid helium for extremely low temperature applications (2-4 K) to mercury (523-923 K), sodium (873-1473 K) and even indium (2000-3000 K) for extremely high temperatures. The vast majority of heat pipes for low temperature applications use some combination of ammonia (213-373 K), alcohol (methanol (283-403 K) or ethanol (273-403 K)) or water (303-473 K) as working fluid.


Either way that's irrelevant. If the temp drops below the boiling temp of the liquid it can no longer turn from liquid to gas, and if that happens the heatpipe no longer moves heat.

Out of curiosity, why did you go from air cooling to subzero phase change vapor chamber? It seems like you missed several intermediary steps in there







Like all of them, in fact.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> I thought most heatpipes used ammonia? Or maybe methanol?


Most of the pc cooling ones use distilled water....which is great for ambient temperature....they just lower the internal pressure so that the water boils in the correct range.

In fact water is by far the best choice in terms of efficiency as its heat of vaporization is about 10X that of most refrigerant gases.
Quote:


> Originally Posted by *ZytheEKS*
> 
> Either way that's irrelevant. If the temp drops below the boiling temp of the liquid it can no longer turn from liquid to gas, and if that happens the heatpipe no longer moves heat.


That's not strictly correct, don't forget the heat pipe is completely sealed, so as you lower the temperature then the pressure within them also lowers which in turn means the boiling point of the working fluid also lowers, heat pipes remain effective down to a few degrees above the freezing point of the working fluid.

In fact that is the basis of my project.....butane normally boils at -1c...but as the temperature goes below that so does the chamber pressure and likewise the butane boiling point.......so the liquid will be always right at its boiling point in a liquid<>vapor equilibrium......the value of that boiling point will depend on the pressure of the chamber and hence in turn its temperature and the chamber temperature will depend on the balance of heat load and cooling capacity.
Quote:


> Originally Posted by *ZytheEKS*
> 
> Out of curiosity, why did you go from air cooling to subzero phase change vapor chamber? It seems like you missed several intermediary steps in there
> 
> 
> 
> 
> 
> 
> 
> Like all of them, in fact.


lol.....that's more difficult to answer......I'll probably annoy a lot of people by saying this but I don't really see the point in water cooling, all that effort and the maximum achievable is just ambient...or perhaps a few degrees below with bong cooling.....so I was much more interested in sub-ambient powered cooling, and a system that can be run 24/7 not just an ln2 powered benchmark and screen shot grab.

My first foray into that was the build I've just dismantled, an air con cooled chill box with all component air cooled within.....but that had its limits in terms of efficiency of air the air cooling and heat pipe/ vapor chamber components not working.

So I started thinking of ways to get around the inefficiency of air cooling and solving the heat pipe problem......a colleague did a similar build using chilled water cooling and while more efficient had many problems of pump failures.

So I decided against including a water loop and started looking for simpler methods, I started by using different gas in the chamber to see if it would greatly increase efficiency but had mixed results.....but the idea of using a different gas led me to think of using a gas that would liquify and perhaps using a self priming pumping system to pump that through cpu/gpu blocks that would just open back into the chamber ie no radiator etc.....that would still be quite simple and allow for the most powerful form of cooling ie phase change.

The problem at that stage was I hadn't thought out the cold line transfer process to store the liquid in a pressure cylinder and it would have been difficult to contain the liquid in gaseous form, I never had any illusion that I'd be able to make a containment vessel strong enough to maintain the pressure necessary to hold the liquid as a liquid at ambient temps.

But once I'd worked out a means of transferring this liquid it occurred to me that I could now use enough to totally submerge the mobo and components and so remove the need for a pumping system at all.

At that time as I'd had no plans to make the chamber pressure bearing much of my thought was centered on how to keep the chamber pressures at atmospheric as I knew I could not contain high pressure gas...but of course that would have meant my component temps would have been limited by the normal boiling point of the liquid at atmospheric pressures.

I was not happy at that limitation and considered many other gases with lower boiling points...but they would have to have been liquid at domestic freezer temps for the transfer process to work.

Then I had the thought that although I could not build a chamber to resist the very large forces required to contain butane as liquid at ambient temps it would be much easier to build a chamber to resist compressive forces and so could use a low pressure chamber.

So I scrapped the plans for a relatively weak chamber to use at atmospheric pressures and went on to the current build which has the advantage of being able to operate at whatever temperature the ac unit can maintain for a given heat load and the working fluid will always be at it's boiling point due to the pressure<>temperature equilibrium.

This last stage has been quite a recent development, and perhaps I haven't put as much thought into that as I could, as Rollie pointed out I could perhaps of done the chamber design better....I was just glad I thought of a way to make the chamber totally self supporting.....still I'm sure it will be sufficient for what is required of it.

Geeez I've done another essay.....better get back to my construction...lol


----------



## technogiant

Made some good progress today, have completed the front sides and back panels, just have to cut out the top and bottom panels now and "let " them into the side panels and the cutting out will be done...thank goodness.


----------



## technogiant

Okay so I'm almost to the end of the panel cutting....what a ball acher that's been....my wrists are almost seized up....but it's all in a good cause









The next stage before assembling the chamber will be running all the cables and pipes through the chamber wall/s.

While I've got a means in mind of running the psu cables through it strikes me it would be much easier to put the psu inside the chamber but I see most are rate for operational use only down to zero degrees......wondering if they contain things like electrolytic capacitors which may freeze at low temps.....I left it outside with my last chamber build just wondering if it would be possible?


----------



## RnRollie

erm, a psu in a box which as some point might be filled with butane gas...
what if a cap pops?


----------



## ZytheEKS

Quote:


> Originally Posted by *RnRollie*
> 
> erm, a psu in a box which as some point might be filled with butane gas...
> what if a cap pops?


A fire needs fuel, an oxidizer, and heat to burn. Butane is not self oxidizing, so if a spark or anything like that happens it's irrelevant because without air it can't burn.

As to actually putting the PSU inside though, I wouldn't mainly because of the fan. You don't know the torque that fan can produce. What if it fails, and the PSU has a fail safe to shut down if the fan stops working? As you said techno, it may have capacitors that could freeze over. Too many unknowns for it to be practical. If you want to try, email the manufacturer first.


----------



## technogiant

nay treble post


----------



## technogiant

double post


----------



## technogiant

Waas apnin wid du duble trebwl post thinggy....than ma first post vanished.

Was trying to say yeah just too many unknowns, I'll leave it out side, it would only add unnecessary heat load to the chamber any way.


----------



## technogiant

doubler again ^


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> doubler again ^


Dear god, something must be wackey with your browser







so many multi posts XD


----------



## technogiant

So I want to run my ideas passed you all for how I'm going to seal the cables in.

One concern I've had about this is that with mineral oil submersion builds a small amount of oil tracks out by capillarity, mainly from the monitor cable.

Obviously I'm concerned about the reverse happening and air being pulled into the chamber because of the negative pressure.

So I'm thinking of running cable extenders through the chamber wall, the cables will terminate in a secondary small chamber stuck on the outside of the main chamber wall.

This secondary chamber will be full of butane gas and attached by a hose to the butane filled collapsible purging sac and so at atmospheric pressure.

These cable extenders will be joined to the proper cables that then exit the secondary chamber and are sealed into that.

So basically the connection between the extenders and the main cable represents a break in the cable sheathing, no pull through will occur from the atmosphere into the secondary chamber as that is kept at atmospheric pressure by the butane filled collapsible purge sac and any pull through that occurs from the secondary chamber into the primary chamber will be butane and not air.

Sorry if that sounds complicated....I'll stick a sketch up shortly.

I'm not sure if I need to do this procedure with all the cables, certainly the monitor cable and lan/ehternet cable will require it. Not sure about usb, sata and fibre optic cables.

Also not sure about the power cables and similar cables with braided wire copper cores, I don't really want to do this with the psu cables as it will involve too many connections and voltage drop as a result ( that's why I was asking about putting the psu in the chamber). I would think that single braided core cables will probably be alright as the resistance to air movement along a length of those would be considerable and so any air entry minimal.

I think the main problems will come from cables that contain several smaller cables where the plastic sheathing around those may contain channels.......to save on too many connections....which may cause a problem with sata and usb I may consider just stripping away the outer sheath on a small section of the cable inside the secondary chamber so as to form a "break" instead of a connection?

Sorry for the edits but I am sound-boarding atm.....I could even dispense with the secondary chamber altogether and just strip the outer case off the cables at the point where they are sealed into the main chamber wall.....that would work...but I'll have to strip a few cables first to see if that is feasible....would certainly save a lot of work.

I may be being a little OTT but I think I'll try to inject the larger braided core power wires with something like this if I can get it to flow through a hypodermic needle.

http://www.ebay.co.uk/itm/CREEPING-CRACK-CURE-leaking-water-leak-sealer-caravan-boat-windows-decks-seals-/141031827140#vi-content


----------



## RnRollie

i can only imagine to separate the wires out so you'll end up with a "flat" cable , like the old IDE flat cables. , with a bit of extra separation between each strand and then epoxy like crazy
in theory there should be no seepage between the copper wires and the (plastic?) insulation.. but yeah well, you'll never know. You can always epoxy the ends where the insulation strips off the copper. But, to be sure, you'ld need solid core wiring like the (stiff) electric 2.5sq wiring, not the twisted strands which are so common to avoid air going capilar.

It seems that you'll have to work with incredible tight tolerances to make this "safe"

But, for the wiring, something shoudl be doable.. after all NASA and some submarine builders managed to do it .









edit: well somebody did file a patent for antennas/cable
http://www.google.com/patents/US5939672

more edit : pointers: http://www.physicsforums.com/showthread.php?t=488030

ultraEdit







just imagine how many visits to the library you'ld have needed if you wanted to do this +20 years ago


----------



## technogiant

Hey Rollie I just cut the plastic off a sata cable to have a little look....consisted of 4 cables grouped into two bundles and wrapped with foil....also had 4 bare wires which I presume are just to strengthen the cable....well it still worked after I cut them any way.

Yeah to me it is starting to look like the problem will be multiple wires in an outer sheath....the casing sheath was quite loose and air would have tracked along that with easy.

So as you said I'd just remove the outer and have a flat cable like an ide ribbon.

Once I'm down to the individual wire level I don't think there will be too much of a problem whether it's a single wire or braided.

I will attempt to seal the braided core wires with some type of glue......but tbh I think even if I left them the amount of air that would track along those would be quite tiny.

Don't forget my chamber has considerable volume...about 135 liters.....and butane is not combustible over 10% concentration so it would take some considerable air ingress to reach that level and I will be re purging it every time before use.


----------



## RnRollie

hmm... i think you should be looking for things which look like the ide adaptor below.
AFAIK things like this exists, or you can probably make them yourself with some printboard.
The connectors/ports/pins themselves are for sale for all kinds of applications - from hobby to industrial (at least they used to be, i haven't picked up a soldering iron in decades)
There should even be exactly what you need, pins (male/male) solid in place. But you need the "big" ones, with the long pins

You cut a slit, slide the board/port through and epoxy/crazy-glue it in place. As long as you dont pull/wiggle the cables 5 times a day it should last









Come to think of it i'm talking about zif & pcb connectors & the like







i'm sure our Chinese friends sell them in bags of 10/100/1000









Pix is just for illustration



.

http://www.cotubex.com/electronics/default.aspx?f2=3&level=1&f3=196


----------



## technogiant

That would be good if I could find pcb pass-through connectors for all the types of connection I need.

The other non pcb type I'd be a little dubious of, there is no guarantee the metal connections are gas tight sealed in those housings or if they can withstand any pressure.

I doubt I'll find the pcb type though....they are normally adapters not just pass throughs.

I think I'm going to have to do a test to see how much air goes through a braided cored wire under pressure.


----------



## technogiant

Okay, so now you can see what I've spend much of the last three weeks doing.....cutting....cutting...CUTTING.

All fitted together quite nicely, couple of high spots need leveling and adjustments to be made but all in all the jobs a good one









I'm going to run the cables and pipes through the chamber walls before I assemble it to make it a little easier to work on.....but that is the back of the project broken...its just ordering stuff and putting it together now.

PS excuse the video...I want to do a video log and it's my first shot at it...lol...it's cut off for some reason so watch it full screen

http://imageshack.us/photo/my-images/69/2jn1.jpg/

Uploaded with ImageShack.us

http://imageshack.us/photo/my-images/837/qlps.jpg/

Uploaded with ImageShack.us

http://imageshack.us/photo/my-images/703/n644.jpg/

Uploaded with ImageShack.us

http://imageshack.us/photo/my-images/703/qadc.jpg/

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http://imageshack.us/photo/my-images/203/b3j7.jpg/

Uploaded with ImageShack.us


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## ZytheEKS

Maybe I'm over simplifying things, but why don't you just strip the wires by hand, and mount the braided strands to to some 16 gauge copper wire? You could easily make an airtight seal with that, and risk no leakage, as it's just a solid piece of copper. It would be a bit of work, but not require any complicated setups, and an easy to seal.


----------



## technogiant

I've abandoned the idea of a secondary chamber to stop cable leakage...overly complicated and I think unnecessary.

Your idea is not over simplifying it at all....often the simplest ideas are the best. I think that would be a good option for the power cables. It would also reduce the number of push together connections which would be better in terms of voltage drop.

But you're right , it would be a lot of work....24 pins on the atx cable, 8 pins additional atx 12v cable, 8 x 8 on the eight pcie power cables, that's 96 pins in all to run through and solder...but this is doable if required.....I think the next step is to run a test on a braided core wire to see how much air does leak through it, I'm guessing the resistance will be so great that it will be completely negligible and we could be trying to solve problems that don't exist.

But if this does need fixing I'll go with your idea...cheers


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I've abandoned the idea of a secondary chamber to stop cable leakage...overly complicated and I think unnecessary.
> 
> Your idea is not over simplifying it at all....often the simplest ideas are the best. I think that would be a good option for the power cables. It would also reduce the number of push together connections which would be better in terms of voltage drop.
> 
> But you're right , it would be a lot of work....24 pins on the atx cable, 8 pins additional atx 12v cable, 8 x 8 on the eight pcie power cables, that's 96 pins in all to run through and solder...but this is doable if required.....I think the next step is to run a test on a braided core wire to see how much air does leak through it, I'm guessing the resistance will be so great that it will be completely negligible and we could be trying to solve problems that don't exist.
> 
> But if this does need fixing I'll go with your idea...cheers


Well, you could always find a prefabbed PCB for as much connections as you can, then manually do the rest with 16gague wire yourself. I know for a fact Bitspower sells a 24pin multi PSU jumper that you could easily modify for your purposes. Just tear off two or three of the jumper ports to make enough space for it to fit in a slot you'll have to make in the aluminum, or however you play to route them through to the inner chamber.

[Edit] It should be noted that the PCB can be removed from the acrylic base that comes with it. [/Edit]

You could do the same with some of their Molex splitters.

It could easily turn a 4 hour job into a 1 hour one.


----------



## technogiant

Yeah nice find there with the pcb Zythe.....I must admit I like your idea of just running solid copper wire through the case if necessary.....nice and simple and avoids too many push connections.

Atm I'm doing a little test on a single braided wire......I've drilled into the side of a valve of a bike inner tube and sealed the end of the wire in there, the wire is 40cm long, the same length as the power extenders, and about the same guage, so it should be a fair comparison. Once the adhesive has set I'll pump up the tube to 10psi and place the other end of the wire in an up turned bottle full of water in a water filled basin.....any air that passes through the wire will collect in the up turned bottle displacing the water......so I'll get an indication of how much of a problem this is....if the experiment works...lol


----------



## technogiant

Well first off I'm glad I did that little test...and it failed badly......confirm significant passage of air along the length of braided core wire......now multiply that by all the cables and there would be a very large air ingress in a short period of time.

I could try and seal each wire with a crack seeking glue....but fear that would be a bit hit and miss....I wouldn't feel I could trust that without testing each cable individually which is out of the question.

I'm re doing the test now with a fine signal wire I've pulled from a sata cable.....waiting for the adhesive to dry again.

If that fails I'll have to go back to the secondary chamber method.


----------



## technogiant

Just tested a signal wire from a sata cable....it's a single stranded core......that appears to be okay no sign of any leakage.....I'm going to have to strip down a sample of each cable I get to see how they are made....seems just the braided ones are the problem.

So that's good news.....I'll use one means or other to overcome the braided cable problem and the single cored signal type wires can just have the bundling sheath stripped off and run through the chamber wall....no need for a secondary chamber....which would have been quite a pain to do


----------



## technogiant

Just stripped down a few different cable types, usb and lan cables.....they both had multi stranded cored wires.....I guessed I cant start cutting and soldering signal wires...that would just mess them up I'd imagine.

So I'm stuck with doing some kind of secondary chamber at least for those cables after all. :-/


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Just stripped down a few different cable types, usb and lan cables.....they both had multi stranded cored wires.....I guessed I cant start cutting and soldering signal wires...that would just mess them up I'd imagine.
> 
> So I'm stuck with doing some kind of secondary chamber at least for those cables after all. :-/


why can't you strip them and mount them to a solid copper wire, then mount the other end to the wire also? As long as you use the correct gauge wire, and don't accidentally mismatch the wires it should be fine. That's what I did with an old XBox360 controller, and it worked fine. (Note: The controller had a USB connection)

As for the Ethernet port, it's fiber optic cables could be an issue. I'm sure you could find a Switchbox splitter, and cannibalize its PCB for your needs. (a smaller switchbox is around $30)


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> why can't you strip them and mount them to a solid copper wire, then mount the other end to the wire also? As long as you use the correct gauge wire, and don't accidentally mismatch the wires it should be fine. That's what I did with an old XBox360 controller, and it worked fine. (Note: The controller had a USB connection)


Oh that's interesting, I didn't think I'd be able to do that sort of thing with a signal cable, thought things like the capacitance of the solder would affect the high frequency signaling etc etc.

May be alright for a controller.....but perhaps not for a usb flash/hard drive...may get data corruption.
Quote:


> Originally Posted by *ZytheEKS*
> 
> As for the Ethernet port, it's fiber optic cables could be an issue. I'm sure you could find a Switchbox splitter, and cannibalize its PCB for your needs. (a smaller switchbox is around $30)


My current router uses a metal lan/ethernet cable not fiber optic, very fine multi stranded wire cores which will need sealing by some means.

The more I think about this the more I'm coming to the conclusion that it will be best to do a mixture of several methods.

I think for the power cables I'll do solid copper wires through the chamber and a soldering job. That will reduce push together connections considerably and hence reduce any voltage drop.

For the sata cables which have bundled single core cables I'll strip off the outer sheath and just pass the individual cables straight through the chamber wall. That will again remove the requirement for extra connections and too much cable length which can be a problem for data transmission.

For the remainder which have bundled multicore signal wires, monitor, lan, usb I think the secondary chamber would be the best approach, all of those cables can have long cable runs and are not so susceptible to problems having additional connections along their route. Additionally I'm not too happy at the thought of interfering with signal wires, cutting and soldering etc as it may cause data corruption and perhaps system instability.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Oh that's interesting, I didn't think I'd be able to do that sort of thing with a signal cable, thought things like the capacitance of the solder would affect the high frequency signaling etc etc.
> 
> May be alright for a controller.....but perhaps not for a usb flash/hard drive...may get data corruption.
> 
> My current router uses a metal lan/ethernet cable not fiber optic, very fine multi stranded wire cores which will need sealing by some means.
> 
> The more I think about this the more I'm coming to the conclusion that it will be best to do a mixture of several methods.
> 
> I think for the power cables I'll do solid copper wires through the chamber and a soldering job. That will reduce push together connections considerably and hence reduce any voltage drop.
> 
> For the sata cables which have bundled single core cables I'll strip off the outer sheath and just pass the individual cables straight through the chamber wall. That will again remove the requirement for extra connections and too much cable length which can be a problem for data transmission.
> 
> For the remainder which have bundled multicore signal wires, monitor, lan, usb I think the secondary chamber would be the best approach, all of those cables can have long cable runs and are not so susceptible to problems having additional connections along their route. Additionally I'm not too happy at the thought of interfering with signal wires, cutting and soldering etc as it may cause data corruption and perhaps system instability.


I wouldn't think solder would cause issues, as long as the two copper wires were in direct electrical contact. It /might/ cause issues, but I / wouldn't think/ it would. There's little point in debating in it.

There's a REALLY SIMPLE way to test it out.

Grab a spare harddrive, which I'm assuming you have one. Load up an operating system on it. Snip a SATA III cable, and try it.








You could easily stress test a hard drive to test stability and data corruption., and a SATA cable has MUCH high bandwidth than a USB 2.0, or even USB 3.0.

You should also note, that if solder DOES cause an issue, you could just mount the cables together with some electrical tape, then coat that in a non conductive silicon based adhesive, even just with liquid electrical tape.









Worst case scenario, you've corrupted a hard drive with absolutely nothing on it. Wipe it, and you're clear with the blank hard drive you had when you started as well as a finite answer.


----------



## technogiant

Yeah thanks for that Zythe,

TBH this is getting more and more problematic.....I've just stripped down a dvi cable.....that is going to be a pigs guts to seal and contains many multi core wires.

I need to have a little re-think on this so sorry if I'm sound boarding and throwing lots of ideas out there.

I'm okay with the power cables and sata cables...its just all the others.

I don't want to be stripping down all those signal cables....just too much room for error and problems....I want to pass them as is straight through the chamber wall and into the secondary chamber.

Problem with that is they would allow too much gas to be sucked through and would empty the purge sac quite rapidly of butane which would go into the chamber and progressively over a period would over fill the gas bottle which can be dangerous....they should not be filled more than 80% with liquid as there has to be a vapor space to allow for expansion (liquid is incompressible).

So I'm thinking of something different for the secondary chamber, rather than having gas filled I could simply submerge the connections so they can't suck air in.

My first thought was mineral oil, but even better may be some type of vegetable oil as that would freeze solid as it was drawn into the cold side of the cable.
Problem with that would be between uses when at ambient temps the oil would track along the cables into the chamber unless I could find a very viscous oil....don't really want to get the chamber all messed up....also butane is soluble in oil and it would provide a route for it to diffuse out of the chamber.

What about dielectric grease? does that melt ? Could I pour that in as a melted liquid?

So my latest thought is to use a low viscosity epoxy resin......on first use I could pour that into the secondary chamber with all my connections joined together, start the chamber up and the low pressure would draw the epoxy into all the channels and so seal them.?


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Yeah thanks for that Zythe,
> 
> TBH this is getting more and more problematic.....I've just stripped down a dvi cable.....that is going to be a pigs guts to seal and contains many multi core wires.
> 
> I need to have a little re-think on this so sorry if I'm sound boarding and throwing lots of ideas out there.
> 
> I'm okay with the power cables and sata cables...its just all the others.
> 
> I don't want to be stripping down all those signal cables....just too much room for error and problems....I want to pass them as is straight through the chamber wall and into the secondary chamber.
> 
> Problem with that is they would allow too much gas to be sucked through and would empty the purge sac quite rapidly of butane which would go into the chamber and progressively over a period would over fill the gas bottle which can be dangerous....they should not be filled more than 80% with liquid as there has to be a vapor space to allow for expansion (liquid is incompressible).
> 
> So I'm thinking of something different for the secondary chamber, rather than having gas filled I could simply submerge the connections so they can't suck air in.
> 
> My first thought was mineral oil, but even better may be some type of vegetable oil as that would freeze solid as it was drawn into the cold side of the cable.
> Problem with that would be between uses when at ambient temps the oil would track along the cables into the chamber unless I could find a very viscous oil....don't really want to get the chamber all messed up....also butane is soluble in oil and it would provide a route for it to diffuse out of the chamber.
> 
> What about dielectric grease? does that melt ? Could I pour that in as a melted liquid?
> 
> So my latest thought is to use a low viscosity epoxy resin......on first use I could pour that into the secondary chamber with all my connections joined together, start the chamber up and the low pressure would draw the epoxy into all the channels and so seal them.?


You know... That gives me an idea... Vehicle manufacturers use a butyl rubber resin to weather proof their headlights, as well as other parts. When punctured and exposed to oxygen it rabidly expands, and drys. You could use a technique similar to this and seal your wires. Something like, use a dielectric resin that requires a resin + a catalyst.

Make the wires absorb the resin through capillary action, or even use vacuum pressure to speed it up, then dry off one end and allow the resin to absorb into the sheathing using vacuum pressure. You could simply clean off the resin on the connector, since it won't harden as it needs a catalyst, then the resin in the cable will harden due to the catalyst already being in the cable.

Sealed cables!!!

Then you risk the catalyst based resin melting the sheathing though








Then again, if it creates an already dielectric barrier would the loss of a sheathing even matter?

Arrrggggghhhg To many things to consider.

Could you simply strip the sheathing off, and use liquid electrical tape to seal the wires? I just realized how easy that would be. It wouldn't require any cutting of the wires, and it would have all the same effects. Then again would the strands being separated for a short time be an issue? *sigh* so many variables


----------



## feznz

thunder bolt how many wires is that?


----------



## technogiant

Yes there is much to be considered.......I had previously thought of trying to seal each wire individually by injecting a creeping crack sealing adhesive.....but of course there are wires within wires here so that would not be possible.....I want to move away from trying to seal each cable individually as one failure could be a big problem and it would be very awkward to test each one.

So it think some form of submersion in the secondary chamber would be the best option...its failure proof so long as the ends are submerged.

I don't really want to go the epoxy resin route.....it would all end up in a solid block and I couldn't check if it had worked properly, there could be bubbles trapped between the connecting cables that would allow for draw through as I'd obviously have to join the connections before I poured the epoxy.

I'm thinking of something like palm oil......It has a melting point of 35c so under ambient temps (at least in my part of the world) it would be solid so no problem with oil tracking into the chamber and messing it up at ambient temps.

I could put my connection together under it as a liquid to ensure no air bubbles in the connections and keep it liquid to allow capillarity to do it's thing for a while and again draw it through by starting the chamber when it is in liquid form.

It wouldn't be so final and irreversible as epoxy resin as I could always just re-flow it by applying some heat.

I don't really think that butane diffusing out through this would be a major problem.....it would be minimal and I'm probably over worrying there.


----------



## technogiant

Quote:


> Originally Posted by *feznz*
> 
> thunder bolt how many wires is that?


I'm not thunderbolt enabled....lol.....no idea about that one.....but don't want to have my hardware choice restricted by my build......there is a way around this as with every problem....it's just thinking out the best way.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Yes there is much to be considered.......I had previously thought of trying to seal each wire individually by injecting a creeping crack sealing adhesive.....but of course there are wires within wires here so that would not be possible.....I want to move away from trying to seal each cable individually as one failure could be a big problem and it would be very awkward to test each one.
> 
> So it think some form of submersion in the secondary chamber would be the best option...its failure proof so long as the ends are submerged.
> 
> I don't really want to go the epoxy resin route.....it would all end up in a solid block and I couldn't check if it had worked properly, there could be bubbles trapped between the connecting cables that would allow for draw through as I'd obviously have to join the connections before I poured the epoxy.
> 
> I'm thinking of something like palm oil......It has a melting point of 35c so under ambient temps (at least in my part of the world) it would be solid so no problem with oil tracking into the chamber and messing it up at ambient temps.
> 
> I could put my connection together under it as a liquid to ensure no air bubbles in the connections and keep it liquid to allow capillarity to do it's thing for a while and again draw it through by starting the chamber when it is in liquid form.
> 
> It wouldn't be so final and irreversible as epoxy resin as I could always just re-flow it by applying some heat.
> *
> I don't really think that butane diffusing out through this would be a major problem.....it would be minimal and I'm probably over worrying there*.


It would be non existent wouldn't it? It will be atmospheric pressure when it's off, and under negative pressure when it's on correct? That's a great idea, if it tries to force in oxygen, it will be stopped at the part of the cable that's filled with the oil. Now we just need to see if theory adds up to reality.







Good luck


----------



## RnRollie

i still think the easiest would be to find some (long) decent quality passthru ports, they DO exist , you are not the first who needs to "connect through a wall"
But you need the quality ones.

Eventually you could build them yourself with the correct connectors soldered onto a (custom) PCB.
Cut through the wall, and epoxy seal the slit with some good stuff. See my amazing paint skills attached

It means to suffer some losses because each cable is using 4 connectors, but that can be mitigated with SHORT quality extender cables
But just having some ports on the walls to plug in stuff would make life a lot easier also.

Most of the stuff can be found where they sell electronics stuff like Velleman kits. for the U.K. this would be Maplins http://www.maplin.co.uk/buy-components/cabinet-hardware/connectors
For the rest of the world... i dont know any chains like Maplins. I'ld use the Velleman website to find where they sellt he kits in your country to find the name of the store that sells electronic components
example for Alabama that would be http://www.vellemanusa.com/shops/?f_State=106&f_Country=58

The best thing about finding such a shop/store near you is that there is a big chance that you can ask them the question "how to connect through a hermetic sealed box"
Note: ask the question on a electronics forum









As for ethernet... forget the ethernet, go wireless. Since you are in a faraday cage, you only need to drill a small hole to lead the inner lead of a coax through, attached to the antenna. The antenna base is solidly mounted to the wall, covering the epoxy filled hole. The mass/earth of the antenna is the box, and since on the inside of the box the outer shield of coax is connectec to the same wall , mass/earth is dealt with











Note: the slit in the wall is chamfered, with the hardened epoxy it prevents the whole port to be sucked through the wall

usefull links:
http://www.maplin.co.uk/
http://www.velleman.eu/home/
http://www.vellemanusa.com/


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> i still think the easiest would be to find some (long) decent quality passthru ports, they DO exist , you are not the first who needs to "connect through a wall"
> But you need the quality ones.
> 
> Eventually you could build them yourself with the correct connectors soldered onto a (custom) PCB.
> Cut through the wall, and epoxy seal the slit with some good stuff. See my amazing paint skills attached


Cheers Rollie...I'm a little concerned about these connector being unknown "black boxes" thing is they are not designed to be air tight, who knows whats going on in there, just because they appear as solid objects they could be as open as a sieve to gas passage. on top of that the chances of me finding pass throughs for all the types of connection I need is nil, so I'd end up with lots of cutting and soldering which I want to get away from.
Quote:


> Originally Posted by *ZytheEKS*
> 
> It would be non existent wouldn't it? It will be atmospheric pressure when it's off, and under negative pressure when it's on correct? That's a great idea, if it tries to force in oxygen, it will be stopped at the part of the cable that's filled with the oil. Now we just need to see if theory adds up to reality.
> 
> 
> 
> 
> 
> 
> 
> Good luck


Well there is a diffusional pressure quite distinct from the actual gas pressure, both oxygen and butane will tend to move from where they are at high concentration ie outside the chamber for oxygen and inside the chamber for butane to where they are at low concentration ie outside for butane and inside for oxygen.

But they have to be able to travel through the medium, oxygen would not travel through the oil but butane would.

I think I'll do a two stage process, firstly I will use heated palm oil that will enter the cables and then form a solid inside them.

The I'd remove the excess palm oil and fill the secondary chamber with glycerine, that is non electrically conductive and will not dissolve butane.

Also it will remain liquid and so I can be sure that all the ends will be sealed.

I'm happy this will be a good solution, in fact I'm so convinced that I will also run the sata and power cables the same way.


----------



## RnRollie

Will MIL-SPEC connectors do for you?

http://www.american-micro.com/connectors.asp
http://www.douglaselectrical.com/
http://www.amphenol-aerospace.com/hermetic.asp
http://www.pavetechnologyco.com/html/home.html
http://www.detoronics.com/

you cant do everything yourself on a budget, at some point you'll have to grab off the shelve (specifically engineered) parts..

But maybe you can get them to sponsor your build... shoot those companies a mail, all it needs is one geek at their end to take an interest.


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> Will MIL-SPEC connectors do for you?
> 
> http://www.american-micro.com/connectors.asp
> http://www.douglaselectrical.com/
> http://www.amphenol-aerospace.com/hermetic.asp
> http://www.pavetechnologyco.com/html/home.html
> http://www.detoronics.com/
> 
> you cant do everything yourself on a budget, at some point you'll have to grab off the shelve (specifically engineered) parts..
> 
> But maybe you can get them to sponsor your build... shoot those companies a mail, all it needs is one geek at their end to take an interest.


Nice searching there Rollie......but really....spend an arm and a leg on specially designed parts that are completely incompatible with the connections I need to make so that I have to cut and solder every cable that enters the chamber on both sides of the chamber wall?

Why would I do that when I can simply pass the cables as they are through the chamber wall and have them submerged so they are completely sealed?

Do you see a problem with the simple solution?


----------



## RnRollie

shooting them a mail is free








Explain them a bit what you are doing and which ports/cables you need to passthru and if they have suggestions or a quote
They might have some solutions close to what you need, or they might quote/build a custom bulkhead for you it might be cheaper than you think

In any case, asking them (shooting a massmail) is free

Dont take this as doubting your skills, but the thing is i'm not convinced you can do this cheap AND simple AND safe; you can only have 2 out of 3


----------



## technogiant

I think what you are suggesting....especially a custom bulkhead is a very good idea.....and is something I may consider in the future.....as I'm building this I'm already considering ways in which I can simplify this, making it smaller much safer, without the need for liquid recovery and a freezer, perhaps even to the point where it could become productized, in which case the custom bulkhead would be a definite requirement.

But ATM it's just an enthusiasts project, proof of concept if you will possibly for future development.


----------



## technogiant

I've been trying to think of the best way of doing this...or rather the best liquids to use to achieve a good seal.

I've been thinking I may use paraffin wax to seal the cables......its probably more consistent and stable than palm oil.
It melts at 40 - 50c so I'd plan on using this first heating it so that it melts and floods and/or is drawn into the cables.

The problem with it is that the remainder in the chamber would then set solid...... I'd rather have a liquid in the chamber to ensure the cables ends were covered and so I could see what is happening in there.

So I was thinking I'd take the remainder out and put another liquid in there just leaving the paraffin wax in the cables as a solid blockage.

As the second liquid I wouldn't use an oil as it would tend to dissolve the paraffin wax out of the cables, but I was thinking of using glycerine/glycerol...it's non conductive and quite viscose, butane is also insoluble in it.

I could even increase its viscosity by dissolving fructose a simple sugar in it to give it a thicker syrup consistency.

This would be a sort of belt and braces approach being a liquid it would be self sealing over the cables within the chamber.

If the the paraffin wax hadn't completely sealed all the cables 100% then the glycerol/fructose would be drawn into that cable and as it became colder as it was drawn into the cable inside the cooling system it would become very viscous indeed and probably need considerably more pressure to push it along the cable than is present.

So that's my thoughts so far.......any opinion on how to improve this are welcome please.


----------



## RnRollie

what do they use in self sealing run flat tires?


----------



## technogiant

Yeah....that had crossed my mind....but no idea of chemical compatibility or electrical conductivity.....I'll have a look









PS....on first inspection just too many chemicals and in-fathomables to consider really.


----------



## RnRollie

ok, this is gonna sound silly...
iso parrafine wax... ordinary margarine or (maybe butter)... good melting temps and when kept cold enough very solid.
Only have to keep it away from rubber.
And as a liquid, there should be plenty that dont dissolve margarine
Anyways, if you use any oil based as primary wicking seal; then ordinary water should do as the secondary liquid. Since oil & water dont mix . And an emulsion doesn't count, as you need to firmly stir to create an emulsion, and i gues your not gonna stir or shake it a lot are you?


----------



## technogiant

Yeah I think any wax, fat or oil that went solid in the required temp range would do, might be better to go with things like paraffin wax though as less likely to degrade than food stuffs.

Just having some concerns about that though....its possible the butane could dissolve that from the other end of the cable?

Couldn't use water as the secondary liquid as it will still be in contact with the electrical connections.

I might just go with the glycerine/fructose solution....that's so viscous that I doubt it would draw far into the cables particularly in the cold sections.

Or maybe just ethylene glycol......not as viscous so may be a problem with tracking at ambient temps but freezes at neg 12c so would freeze solid and block cables during use.

neither glycerol/fructose or ethylene glycol would be affected by butane

PS....think I've finally thought through the best way to do this, I'll start by using glycerol/fructose, that is very viscous but if it gets progressively sucked too far in then I'll take that out of the container and replace it with paraffin wax, that will completely seal the cable ends and prevent the glycerol being pulled any further along the cables, the glycerol in the cables will form a barrier preventing the butane from getting to the paraffin wax and dissolving it.

Job done....time to move on and do this.


----------



## mindblowingj

Quote:


> Originally Posted by *RnRollie*
> 
> Will MIL-SPEC connectors do for you?
> 
> http://www.american-micro.com/connectors.asp
> http://www.douglaselectrical.com/
> http://www.amphenol-aerospace.com/hermetic.asp
> http://www.pavetechnologyco.com/html/home.html
> http://www.detoronics.com/
> 
> you cant do everything yourself on a budget, at some point you'll have to grab off the shelve (specifically engineered) parts..
> 
> But maybe you can get them to sponsor your build... shoot those companies a mail, all it needs is one geek at their end to take an interest.


Been following the thread and id have to say, I agree with Rollie on this one, I think it's not really the simplest solution to seal the way you're intending to. So I went trough those and isint http://www.pavetechnologyco.com/design/paveseal_productindex.html the exact thing you need ? To me it dosen't look like anything pricy, you would probably have to get the hole made professionally but in the end I feel like the design would be safer and cleaner.


----------



## technogiant

I agree that using a specifically designed pressure tested pass through has to be better in as much as it is tried tested and guaranteed.

What is not so certain is that cutting and resoldering every cable on either side of the chamber wall, including the signal wires will not have a detrimental effect. These signal cables are built in a very specific way....wires grouped together in separate groups interwound around each other and then separately shielded from the other groups of cables because of the way the individual wires can interact through electric fields surrounding them...you can't just cut these things randomly and stick dollops of solder (which may have capacitance) on them and ensure they are going to work correctly.

If I could get purpose built pass throughs for every type of connection so I could just plug into them that would be ideal....but they don't do them...and I'm not going to spend out for custom made parts...I'm not a rich man.

The bottom line is my cheap skate work around cannot fail.......air cannot be drawn through liquid full stop......the worst that could happen is that the liquid would be drawn into the chamber and with the viscous guup I'm using that won't happen in a flash ....and of course I'll be monitoring to see that's not happening.....so worst case scenario I get a mess in the chamber and have to use a different sealing fluid.

Granted it won't be as professional as a pucker connection...but it will work.


----------



## RnRollie

Drastically minimising the cabling needed will help also

-you cant keep a HardDrive in the cold chamber, they dont like below 0 °C very much, however, an SSD should be ok to -30 °C
-consider riser boards: (see also DELL & ITX), if you use a riser board which incorporates most of the IO panel or a raid controller; then you only need to passthru the PCI riser flat cable





As for sealing the cables, would crayotherm work for you?
http://www.heatmanagement.com/en/produkte/thermally-conductive-phase-change-wax-crayotherm,43

PS: pricey is relative: a completely sealed ethernet port can be had for $400,- thou i wonder why they need ethernet in a F-35 jet fighter.
http://www.pavetechnologyco.com/design/pdf/3273.html

They've got cheaper stuff too








http://www.pavetechnologyco.com/html/pricelist.html


----------



## ZytheEKS

Quote:


> Originally Posted by *RnRollie*
> 
> Drastically minimising the cabling needed will help also
> 
> -you cant keep a HardDrive in the cold chamber, they dont like below 0 °C very much, however, an SSD should be ok to -30 °C
> -consider riser boards: (see also DELL & ITX), if you use a riser board which incorporates most of the IO panel or a raid controller; then you only need to passthru the PCI riser flat cable
> 
> 
> 
> 
> 
> As for sealing the cables, would crayotherm work for you?
> http://www.heatmanagement.com/en/produkte/thermally-conductive-phase-change-wax-crayotherm,43


Quote:


> Kunze phase-change materials *are not electrically insulating.* They consist of pure phase-change polymer.
> 
> We disclaim all liability for accuracy of this information. Technical detail is subject to change.


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> Drastically minimising the cabling needed will help also
> 
> -you cant keep a HardDrive in the cold chamber, they dont like below 0 °C very much, however, an SSD should be ok to -30 °C
> -consider riser boards: (see also DELL & ITX), if you use a riser board which incorporates most of the IO panel or a raid controller; then you only need to passthru the PCI riser flat cable
> 
> 
> 
> [/quote
> 
> And the cores on those ribbon cables are single stranded or multi stranded?...if they are the latter they will still need sealing...so possibly no improvement really.
> 
> Yeah I've always mounted both my HDD and SSD outside the chamber.....the specs I've seen on ssd's show that they can only be stored at low temps not operated at low temps...not quite sure why that is so have avoided putting them in there.


----------



## RnRollie

@ZytheEKS
i know its not insulating, thats why its usable for sealing the stranded cables ONLY ; one-by-one not all in one go
Its usage is for the primary cable seal; not to replace the slushing liquid in the sealing chamber









Quote:


> Originally Posted by *technogiant*
> 
> And the cores on those ribbon cables are single stranded or multi stranded?...if they are the latter they will still need sealing...so possibly no improvement really.
> 
> Yeah I've always mounted both my HDD and SSD outside the chamber.....the specs I've seen on ssd's show that they can only be stored at low temps not operated at low temps...not quite sure why that is so have avoided putting them in there.


i doubt they are multi stranded, if so, then its to reduce EM influences. The importance of that depends on what functionality exists on the daughterboards. You wont be using any vital hi-speed transfers i assume.

The idea is that using a "remote I/O panel" daughterboard requires only one pci- cable -which might or might not need sealing compared to having to seal ALL of the cables you want to use

If you want to have 4 USB ports, you have to seal two USB stranded/wire cables
If you have one PCI-e 1x card with 4 USB ports, you only have to seal one pci-e stranded/wire cable
if you want to attach 1 SSD, 1 HD, 1 optical drive , you have to seal 3 SATA stranded/wire cables
if you have a PCI-e 4-port drives i/o card , you only have to seal ONE pci-e stranded/wire cable

Its only a matter of finding a card which incorporates the most functions

It's not the solution, but an improvement , its less work

Mice & keyboard are wireless, so no cables there - you only need to drill a hole in the wall and epoxy the wireless (bluetooth/I.R/?) receiver there
Networking wireless also. Wireless receiver (old school : a coax between the antenna and the WIFI card, and the coax doesn't even have to go through the wall, only the antenna does, and that is THE easiest mount you can do









That leaves what? Power?. DVI-D?


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> @ZytheEKS
> i know its not insulating, thats why its usable for sealing the stranded cables ONLY ; one-by-one not all in one go
> Its usage is for the primary cable seal; not to replace the slushing liquid in the sealing chamber
> 
> 
> 
> 
> 
> 
> 
> 
> i doubt they are multi stranded, if so, then its to reduce EM influences. The importance of that depends on what functionality exists on the daughterboards. You wont be using any vital hi-speed transfers i assume.
> 
> The idea is that using a "remote I/O panel" daughterboard requires only one pci- cable -which might or might not need sealing compared to having to seal ALL of the cables you want to use
> 
> If you want to have 4 USB ports, you have to seal two USB stranded/wire cables
> If you have one PCI-e 1x card with 4 USB ports, you only have to seal one pci-e stranded/wire cable
> if you want to attach 1 SSD, 1 HD, 1 optical drive , you have to seal 3 SATA stranded/wire cables
> if you have a PCI-e 4-port drives i/o card , you only have to seal ONE pci-e stranded/wire cable
> 
> Its only a matter of finding a card which incorporates the most functions
> 
> It's not the solution, but an improvement , its less work
> 
> Mice & keyboard are wireless, so no cables there - you only need to drill a hole in the wall and epoxy the wireless (bluetooth/I.R/?) receiver there
> Networking wireless also. Wireless receiver (old school : a coax between the antenna and the WIFI card, and the coax doesn't even have to go through the wall, only the antenna does, and that is THE easiest mount you can do
> 
> 
> 
> 
> 
> 
> 
> 
> 
> That leaves what? Power?. DVI-D?


Tbh Rollie it's not going to be any work at all running the sata , usb, lan and digital audio out of the box they are not the concern in that respect.....so to replace those with a ribbon cable instead with a daughter board swinging around on the end of it would only be an advantage if I didn't have to seal the cables internally, which I may have to anyway, and tbh I'm happier sealing all the cables by using my "slush box" regardless of core type as its more certain. I may as a belt and braces approach also inject some creeping crack sealing adhesive into the cables internally.....no need to go high tech with that phase changing sealant you found...that's essentially exactly what my "slush box" is doing....except it does all the cables quickly and easily in one go....and is electrically non conductive.

No the harder job in respect of sealing the cables through the wall will be the bundled power cables, they all have to be separated so they are not touching one another and so opening channels between them.......but surprise surprise...I have a plan for that....lol


----------



## technogiant

Well I've ordered all the cables extenders I need to go on to the next stage now...so it will be a few days before they arrive so I can get on with planning their exact layout through the wall.

Once I've done that I'll be running the hoses.

I need three hoses in all, one with a shut off valve leading from the chamber to an expansion sac, one with a shut off valve leading to a purge line and the atmosphere, and one to connect the gas bottle to the chamber sump.

For the first two I was considering this:-

http://www.ebay.co.uk/itm/Hose-adaptors-with-taps-ball-valve-3-8-BLACK-vacuum-hose-line-shut-off-/261249231625?pt=LH_DefaultDomain_3&hash=item3cd3aaeb09

It's called a vacuum line shut off.......I'm not 100% sure but I'd imagine the shut of valve is a ball type and will work regardless of which end of the pipe is under vacuum/pressure?......any hvac engineers in the house?

For the third hose connecting the gas cylinder to the chamber sump I've specifically picked this one:-

http://www.gaslow.co.uk/pages/products/list_2.htm

I'd be going for the 2.0 meter hose with the 21.8 LH fitting to be connected to the 15kg butane cylinder using this fitting:-

http://www.gaslow.co.uk/pages/products/list_3.htm the 01-1670 on top of the list......as a matter of interest I'd guess that also has a ball type sealing valve?

The reason I've gone for the flexible stainless steel hose is that it will be carrying liquid butane between the chamber and cylinder, I will have to move the cylinder in and out of the freezer so I'd require the hose to be flexible to a small degree at low temps, rubber hoses can crack/split at low temps as they lose flexibility and I don't want that to happen...that would be a catastrophic failure dumping a large quantity of liquid butane out of the system.....so I've gone for this rather expensive flexible stainless steel hose.
It has the added advantage that it wont suffer plasticizer extraction which would contaminate my components and possibly lead to hose blockage.

Here's a pdf spec sheet on it :-

http://www.gaslow.co.uk/pdf/Stainless_Steel_A4.pdf


----------



## RnRollie

no B&Q nearby ?









personally i dont like buying "never used" stuff from ebay - too many dodgy elements ; then again i once bought a car from a geezer in Thirsk on ebay









that first hose, i think the direction matters ; AFAIK you need to shut off at the pressure/vacuum side (left in the pic) -not want to leave the hose pressurised/stressed- to avoid slow leaks, & strain. But how crucial it really is? dont know. Comes down to "good practice" i guess. Really need someone who knows... If you're lucky some geezer at B&Q might know, otherwise walk into a shop like gaslow







There MUST be a plumbers / hvac forum somewhere on the internet (rule 34 applies) which has the info.

As for the stainless hoses... AFAIK these are "regular rubber" hoses with a braided SS shield. THe SS shielding being there to protect the rubber hose and to prevent rupture in case of overpressure.

I assume you are going to drill and tap and use real hose connectors/fittings on the chamber walls? As running braided SS through the wall will give you the same problems as you have with the wires. But i guess you worked that out for yourself allready.

Seems to be coming together nicely.. plod on


----------



## technogiant

Yeah I hear what you're saying about ebay...but sadly they don't sell this sort of thing at BnQ,.... but I'll look for a more reputable supplier.

You've raised some interesting points there about the hoses...thanks...that's the reason I'm throwing this out there.

As regards the vacuum line hose and valves, I was considering that the whole unit would be suitable for use under sustained vacuum not just the metal section at the end...after all it does say vacuum line not just vacuum valve.

So I've been looking around the web at other vacuum line hose and valve assemblies......I've found many described as vacuum line with shut off valves that have rubber hose sections on both sides of the valves.....so I think that having metal on the one side and rubber on the other is just a peculiarity of that particular assembly and not necessary for safe function.

But I do take your point that it may not be best practice to leave a rubber hose under constant load....those hoses will actually only be under compressive load when the unit is in operation and not 24/7....most of the time they will be under no net pressure either compressive or expansive.

I don't intend to thread and connect any of hoses into the chamber...they will simply be fixed via adhesive.....they are under no more load than the cables which penetrate the chamber wall and i see no reason they should be secured in a stronger fashion.

With the rubber hoses I will however bond them to the chamber via their terminal metal fittings.....if I just used the rubber to seal to the chamber wall then pressure compressing/squashing the rubber could tend to break apart the adhesive joining the rubber to the chamber wall.....any such deformation would obviously not occur with the terminal metal fittings.
Quote:


> Originally Posted by *RnRollie*
> 
> As for the stainless hoses... AFAIK these are "regular rubber" hoses with a braided SS shield. THe SS shielding being there to protect the rubber hose and to prevent rupture in case of overpressure.
> 
> I assume you are going to drill and tap and use real hose connectors/fittings on the chamber walls? As running braided SS through the wall will give you the same problems as you have with the wires.


I'm not sure you've had a good look at those they are not just normal rubber hoses with stainless steel braiding to reinforce them, they actually have an internal flexible SS tube running through the center as well as the outer SS braiding.

As they claim that there is no extraction of plasticizer from the rubber then the inner SS tube must be a completely sealed tube in itself just being reinforced with the outer rubber and SS braiding.

Again my original intention was not to use threaded fittings but just to pass the SS hose through the chamber wall sealing further along its length so that the end would be right at the bottom of the chamber sump.......but yes have doubts that the braiding may compromise the chamber integrity.

Its difficult to know how the end is sealed in this respect and is something I'm going to have to suck and see as it were although it does say in the pdf the ends are welded but that is no guarantee the outer casing is air tight....it may be necessary to butcher the end and so terminate the braiding outside the chamber and continue the inner SS tube inside to the chamber sump...but I'd need the inner SS Tube to be completely intact as it will be drawing the liquid out by suction so needs to be a completely sealed tube in itself...or if the central SS tube is not a completely sealed tube I may need to just extend the SS inner tube with a short length of pvc tube running into the sump...this is something I'm going to have to play by ear until I have the items in hand.

PS.....In fact Rollie your comments about the SS braiding have made me think further about the rubber hose....if you look at a cross section of hvac rubber tubing you will see that they are also reinforced with a layer of some type of cord...this again could be an issue and these hoses were not designed to form a seal with the outer layer of the hose but with the inner layer...so it may be neither of them will prevent atmospheric air from entering the chamber in my usage scenario.

This again is something I'm going to have to test when I get them.....it may be that I'll have to terminate the hoses with some type of metal spigot fitting which is sealed into the chamber wall.....but tbh....looking around at the various fittings I can get...this problem should be easily overcome.


----------



## RnRollie

i'ld go for drilling through, tapping/threading & screwing in quality bulkhead fittings (with good norprene & ss washers) - maybe even considering ball-valved bulkhead fittings; as it seems less convoluted to me; but htats just how i would do it, but i might be wrong doing it like that


----------



## rafety58

how have I not seen this yet, posting to sub


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> i'ld go for drilling through, tapping/threading & screwing in quality bulkhead fittings (with good norprene & ss washers) - maybe even considering ball-valved bulkhead fittings; as it seems less convoluted to me; but htats just how i would do it, but i might be wrong doing it like that


Lol.....I'm sure that is the correct and proper way to do it.....IF I was trying to contain the gas under pressure at 50psi and greater.....but I'm not,at a max of neg 10psi and more probable operating pressure of neg 5psi these pipes will be just fine sealed up with adhesive.

Quote:


> Originally Posted by *rafety58*
> 
> how have I not seen this yet, posting to sub


Welcome


----------



## technogiant

Just a little tease, I've been cutting my mobo tray so that it all fits nice in the basin......cables I've ordered are starting to come through, once I've got them all and I can see exactly how they will go I can start running them through the chamber wall.

http://imageshack.us/photo/my-images/802/hxes.jpg/

Uploaded with ImageShack.us


----------



## RnRollie

been looking at your sketches again, and i suddenly realised what would probably be the coldest parts of the chamber... the walls








Can't cheat Newton & Bernoulli out of their rightfull place









Anless i'm wrong, at the phase change point, the Butane gas will not go "straight up", but will have the tendency to "cling" to the walls (ok, maybe just a little) , then again, i assume the "hottest" part will be more to the center, so the gas will have to move across the surface towards the walls.

Performance might be better/different as expected, as part of the liquid butane "drip off" from the evap will evap before it reaches the (boiling) pool at the bottom.

of course, all this changes if you put a fan in the chamber









Anyways, i might be wrong on the above.. just thinking out loud


----------



## technogiant

I like thinking out loud.....that's how I evolve my thoughts....lol...









It's a job to know how exactly this will work.....with heat pipes and vapor chambers the production of vapor at the heat source causes a pressure increase which travels at the seed of sound throughout the pipe/chamber which when it hits the cold area causes condensation because the pressure it too high for the corresponding temperature....so its not necessarily the gas that is evolved that is recondensed but the pressure change it generates causes condensation of other gas in the cold area.

But with a chamber the size of mine....about 135 liters...because a given amount of gas generation will be relatively small in comparison to the total volume I'd imagine that pressure changes will be less pronounced and it may be that heat movement is more via circulation of the heated gas to the evap.

That's why I am having fans in there, if it acts as a heat pipe they should not be needed as heat exchange is due more to pressure changes, but if heat exchange is more due to the movement of hot gas then I guess the fans would be required.....something to try...if it works at all :-/

Ps the coldest part will always be the evaporator...everything else will be warmer by some degree, it will be place vertically above the basin inside the chamber..


----------



## technogiant

Okay Rollie you officially concerned me with your comments on the braiding in the flexible Stainless steel hose and I was also concerned about the cord braid reinforcement in the rubber type hoses as the way I was planning to do it could have possibly compromised the chamber integrity if this braid had let gas through.

So I've been hunting for solutions (low tech cheap ones obviously







)

I've found this vacuum line shut off valve

http://www.hvacstore.co.uk/acatalog/Large_Bore_Vacuum_Line.html?gclid=CIvkob3hhbkCFbIPtAodYSIA8Q

And these 6mm to 8mm spigots

http://www.ebay.co.uk/itm/270639659381?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

As the vacuum line is 6mm I'll insert a spigot into each end so I can seal the spigot into the chamber rather than the pipe. (so the cord braid ends outside)

The Flexi SS hose was a little more difficult, they come prefixed with a 21.8 LH nut fitting on the one end which goes to the gas bottle or gas bottle adapter and on the other end they have a W20 nut fitting which normally screws to the high pressure side of the pressure regulator body.

But I've found an adapter called a hose extender made by the same company, basically a solid metal fitting with a W20 end and a 21.8 LH end....so I'll get a 45cm Flexi SS hose and a 150cm Flexi SS hose and join them with this connector. I'll seal the connector into the chamber wall where it passes through so there is no continuation of the braiding into the chamber....







......I'll have to cut the nut off the end that dips into the chamer sump though so I can get the end of the hose right to the bottom to drain it out.


----------



## technogiant

Just some thoughts that have occurred to me while I'm building this which may have made this all a lot easier in terms of build and if anyone else is considering anything as extreme as this then it may offer some pointers.....I don't think I'm going to change the course of my build atm.

Firstly the project relies on the low pressure in the chamber lowering the boiling point of the liquid butane so that it's always right on the boiling point in a liquid<>vapor equilibrium.

Well if that is possible and it works (which it should....simple laws of physics) then there is no reason I couldn't have used a different liquid with a higher boiling point....say refrigerant R11 boiling point +29c.....it would have required a lower pressure in the chamber to attain the same boiling point but the lowest you can go is -15psi anyway as that is one atmosphere and I'll be using -10psi as it is.

So using a liquid with a boiling point of around ambient would have meant I could has done without the freezer and the more complex cold line transfer method to recover the liquid butane to a pressure bottle.

Secondly It has struck me that what will be going on in my chamber.......ie the evaporation of liquid to gas to cool the components is exactly the same thing that's happens in the ac unit evaporator.....so it may be possible to eliminate the ac unit evap and use the chamber as the evaporator?

Simply have the capillary tubing opening directly into the chamber and also the compressor suction line.

It would be more direct, so instead of having the compressor causing pressure drop in the evaporator which causes a low temperature, which cools the chamber which causes low pressure......simply eliminate the evap and connect the compressor to the chamber.

There would be a problem with lubricant return...but you could probably over come that by having the cap tube opening into an open wide necked receptacle that then narrows into the return suction line....the refrigerant would boil off leaving the lubricant which is non volatile to drop into the receptacle and so return via the suction line.

This would allow you to may the chamber so much smaller.

Like I said.....I'm not going to change direction now.....but I think for the future I may learn some hvac skills and get some equipment......I see another project down the line.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Just a little tease, I've been cutting my mobo tray so that it all fits nice in the basin......cables I've ordered are starting to come through, once I've got them all and I can see exactly how they will go I can start running them through the chamber wall.
> 
> http://imageshack.us/photo/my-images/802/hxes.jpg/
> 
> Uploaded with ImageShack.us


You took precaution to prevent static discharge onto the motherboard tray I presume? If not, you might want to do that.


----------



## technogiant

Well I have the mobo mounted on a tray using the stand off's.....so it wont short by that means.....not sure thats what you meant though...can you elaborate please.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Well I have the mobo mounted on a tray using the stand off's.....so it wont short by that means.....not sure thats what you meant though...can you elaborate please.


Most every case I've seen has the motherboard tray electrically insulated from the case itself. When I went to the electronics store to pick up some parts, and get some advice for building a DIY chassis they emphasized to keep the MoBo tray out of direct electrical contact from the case.


----------



## mindblowingj

still no oxygen inside there, so static discharge isn't (shouldn't) be dangerous.


----------



## ZytheEKS

Quote:


> Originally Posted by *mindblowingj*
> 
> still no oxygen inside there, so static discharge isn't (shouldn't) be dangerous.


... That is a good point, and ugh... Well made.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Most every case I've seen has the motherboard tray electrically insulated from the case itself. When I went to the electronics store to pick up some parts, and get some advice for building a DIY chassis they emphasized to keep the MoBo tray out of direct electrical contact from the case.


Oh that's something I wasn't aware of......its not at the moment...but should be quite easy to do...thanks for that.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Oh that's something I wasn't aware of......its not at the moment...but should be quite easy to do...thanks for that.


Yup, static dischage was the reason given. Apparently a charge can build up on the case, and if the mobo tray is in electrical contact with the case, the charge is transferred to the mobo tray. If the charge gets big enough it can discharge onto the mobo (which is bad for obvious reasons)

As MindBlowingj pointed out, it's submerged in a dielectric fluid so that shouldn't be an issue. (Which I hadn't considered when I commented about it.)


----------



## technogiant

I'm not sure about this now......I take Mindblowing's point that static discharge would not be an issue in that it would not cause ignition, but static can travel through other materials.

I know things just like moving gas can build up static charge....and there will be a lot of that in there.....but I guess the large capacitance of the >60kg aluminum case will act as a ground for that.....but in that instance would it not be better to have the mobo grounded to the alu case so that it was at the same charge as the gas that will be incontact with it??...not sure what would be for the best??......it would be easy to either isolate it or leave it connected as is now....just don't know in these particular circumstance which would be the right thing to do?


----------



## mindblowingj

Ha makes a lot of sense, I tried to find a read giving some indication if there wold be a static build up inside chamber or on it's walls, seems to be no.
Quote:


> Hydrocarbon liquids without static dissipater additive may have conductivity below
> 1 picoSiemens per meter (pS/m). The highest electro-static ignition risks are
> associated with "ultra-low conductivities" below 5 pS/m. See Section 7 for sources
> of information on defining safe loading and handling procedures for low
> conductivity products. Note that conductivity can be reduced by environmental
> factors such as a decrease in temperature."


source


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I'm not sure about this now......I take Mindblowing's point that static discharge would not be an issue in that it would not cause ignition, but static can travel through other materials.
> 
> I know things just like moving gas can build up static charge....and there will be a lot of that in there.....but I guess the large capacitance of the >60kg aluminum case will act as a ground for that.....but in that instance would it not be better to have the mobo grounded to the alu case so that it was at the same charge as the gas that will be incontact with it??...not sure what would be for the best??......it would be easy to either isolate it or leave it connected as is now....just don't know in these particular circumstance which would be the right thing to do?


Even if the static charge was created it wouldn't be able to transfer itself to the motherboard as the dielectric fluid will act as an insulator.

If you're super worried about it, just spray the bottom of the mobo tray with some liquid electrical tape. A simple answer with no foreseeable repercussions

Problem solved, if there was one there to begin with.


----------



## technogiant

Quote:


> Originally Posted by *mindblowingj*
> 
> Ha makes a lot of sense, I tried to find a read giving some indication if there wold be a static build up inside chamber or on it's walls, seems to be no.
> source


So you think it may be better to ground the mobo to the case? ....the case would act as a dissipator for any charge in the gas so preventing static build up and if the mobo was at the same potential there should be no problem??


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Even if the static charge was created it wouldn't be able to transfer itself to the motherboard as the dielectric fluid will act as an insulator.
> 
> If you're super worried about it, just spray the bottom of the mobo tray with some liquid electrical tape. A simple answer with no foreseeable repercussions
> 
> Problem solved, if there was one there to begin with.


Yeah it would be easy to do either way.....I'm just not sure what is the correct thing to do in these circumstances...my gut is telling me the mobo should be grounded to the case as this has a lot of conductive contact with the gas (the gas can build static) so everything would be at the same potential, if the mobo was isolated then it could in theory be at a different potential and subject to static discharge from the surrounding gas.


----------



## feznz

Is this one of those threads that will all of a sudden com to a grinding halt were we will all be wondering did it work? or did technogiant blow himself up?
technogiant which city do you live in so we can keep an eye on the news







Just in case


----------



## ZytheEKS

Quote:


> Originally Posted by *feznz*
> 
> Is this one of those threads that will all of a sudden com to a grinding halt were we will all be wondering did it work? or did technogiant blow himself up?
> technogiant which city do you live in so we can keep an eye on the news
> 
> 
> 
> 
> 
> 
> 
> Just in case


Let us hope not! Explosives are fun right up until someone gets hurt.


----------



## technogiant

If this goes wrong you'll know.....It will register on the "Richter scale" even as far as NZ.

but in case it doesn't it's Wales UK.....only a small country but full of fantastic minds....









Ps...on a side note to this talk of explosions and static electricity....I will be following a safe procedure to fill the chamber with gas...as has been noted above transfer of insulating gases can lead to static charge build up.....that's why before I fill the chamber with butane I will as a first step be filling it with nitrogen(oxygen free), that will reduce the oxygen content down below the LOC or lowest oxygen level to support combustion....approx 12%.....then I'll fill with butane as close to 100% as I can as the highest concentration of butane in a butane/air mix that can support combustion is 11% (UEL or upper explosive limit).....so at no stage during the fill procedure will there be a point where there are explosive levels present.....so if static discharge were to occur then it will still be safe.


----------



## technogiant

doubler


----------



## technogiant

Okay now I'm officially really excited.....I've just ordered a sheet of panasonic pyrolitic graphite sheet to use on my cpu as a heat spreader....I went for the 70 micron thickness one that has a lateral heat conductivity of 1000w/m/k!!!!

I went for the version that has a 10 micron layer of acrylic adhesive on the one side...so I'll be able to adhere it directly to the cpu IHS no need for a TIM.

I'm not going to attach it as a complete sheet but will cut it into small sections 1cm X 3cm which will then be folded into a "U" so that the center 1cm X 1cm will stick to the cpu and the two side 1cm X 1cm sections will stick up like little fins and will be coated with 10 micron aluminum oxide dust which I already have as a nucleation promoter. should be able to fit 16 of those on the IHS.

If this works out this is going to be the mother of all evaporator surfaces.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> *Okay now I'm officially really excited.....I've just ordered a sheet of panasonic pyrolitic graphite sheet* to use on my cpu as a heat spreader....I went for the 70 micron thickness one that has a lateral heat conductivity of 1000w/m/k!!!!
> 
> I went for the version that has a 10 micron layer of acrylic adhesive on the one side...so I'll be able to adhere it directly to the cpu IHS no need for a TIM.
> 
> I'm not going to attach it as a complete sheet but will cut it into small sections 1cm X 3cm which will then be folded into a "U" so that the center 1cm X 1cm will stick to the cpu and the two side 1cm X 1cm sections will stick up like little fins and will be coated with 10 micron aluminum oxide dust which I already have as a nucleation promoter. should be able to fit 16 of those on the IHS.
> 
> If this works out this is going to be the mother of all evaporator surfaces.


Dear lord, you're using graphene foam as an TIM? That must have cost a pretty penny. Let's hope it was worth the $$$.
Careful when applying tension from the IHS to the HS as it was my understanding the graphene foam is fairly brittle.


----------



## technogiant

It's not graphene foam.....its a sheet of very thin graphite film...here's a link

http://www.panasonic.com/industrial/electronic-components/protection/pyrolytic-graphite-sheet.aspx

And didn't cost the earth with delivery and tax a mere £27.

I'm not using it as a tim...there is no heat sink .....just the graphite sheet.....remember I was having some concerns about the choosing a suitable tim for this application...well this solves that problem and removes the need for a heat sink as I choose the one with a 10 micron layer of acrylic adhesive on the back.....it will just stick directly to the IHS.

I'm hoping the acrylic adhesive will not dissolve in the liquid....I know acrylic/plexiglass is okay with it...but just trusting to luck on that....but a good thing with using this is that the adhesive layer is so thin at 10 microns it will offer very little thermal resistance.

What changed my mind from the all copper 1u server cooler I was going to use was this article I saw at "semi accurate"

http://www.panasonic.com/industrial/electronic-components/protection/pyrolytic-graphite-sheet.aspx

Part way down the page it quotes the thermal conductivity in the perpendicular plane...ie not the headline lateral conductivity of 700-1900 w/m/k, but the conductivity at 90 degrees to that perpendicular to the sheet.....that ranges fro 10-26 w/m/k for the 10micron and 100 micron thickness sheets respectively so I guess my 70 micron sheet will be in-between those values.

But it struck me that the conductivity was no worse than a standard tim and that if I was to simply stick a whole sheet on the IHS I'd still get the same heat transfer in a perpendicular direction over the area of the IHS as I would get with a normal tim that I'd have to use IF using a heat sink.

So as heat transfer through a tim to any heat sink is obviously going to be the bottle neck....then using a sheet of this stuff would not reduce heat flow to the surface area directly above the IHS any more than a TIM....so I could just apply a nucleation coat to that area of the sheet and get just as good heat removal potential as using a tim/heatsink and would have the added benefit of the huge lateral conduction to the remainder of the sheet 12cmX 9cm.

I'm still toying with ideas but thinking it may be better rather than applying it as a whole sheet but to cut it into stripes to make fins over the surface of the IHS....may be more work but would increase the surface area in close proximity to the heat source so the heat would not have to travel as far to be removed.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> It's not graphene foam.....its a sheet of very thin graphite film...here's a link
> 
> http://www.panasonic.com/industrial/electronic-components/protection/pyrolytic-graphite-sheet.aspx
> 
> And didn't cost the earth with delivery and tax a mere £27.
> 
> I'm not using it as a tim...there is no heat sink .....just the graphite sheet.....remember I was having some concerns about the choosing a suitable tim for this application...well this solves that problem and removes the need for a heat sink as I choose the one with a 10 micron layer of acrylic adhesive on the back.....it will just stick directly to the IHS.
> 
> I'm hoping the acrylic adhesive will not dissolve in the liquid....I know acrylic/plexiglass is okay with it...but just trusting to luck on that....but a good thing with using this is that the adhesive layer is so thin at 10 microns it will offer very little thermal resistance.
> 
> What changed my mind from the all copper 1u server cooler I was going to use was this article I saw at "semi accurate"
> 
> http://www.panasonic.com/industrial/electronic-components/protection/pyrolytic-graphite-sheet.aspx
> 
> Part way down the page it quotes the thermal conductivity in the perpendicular plane...ie not the headline lateral conductivity of 700-1900 w/m/k, but the conductivity at 90 degrees to that perpendicular to the sheet.....that ranges fro 10-26 w/m/k for the 10micron and 100 micron thickness sheets respectively so I guess my 70 micron sheet will be in-between those values.
> 
> But it struck me that the conductivity was no worse than a standard tim and that if I was to simply stick a whole sheet on the IHS I'd still get the same heat transfer in a perpendicular direction over the area of the IHS as I would get with a normal tim that I'd have to use IF using a heat sink.
> 
> So as heat transfer through a tim to any heat sink is obviously going to be the bottle neck....then using a sheet of this stuff would not reduce heat flow to the surface area directly above the IHS any more than a TIM....so I could just apply a nucleation coat to that area of the sheet and get just as good heat removal potential as using a tim/heatsink and would have the added benefit of the huge lateral conduction to the remainder of the sheet 12cmX 9cm.
> 
> I'm still toying with ideas but thinking it may be better rather than applying it as a whole sheet but to cut it into stripes to make fins over the surface of the IHS....may be more work but would increase the surface area in close proximity to the heat source so the heat would not have to travel as far to be removed.


How is Pyrolytic carbon different from graphene foam?

They are both formed by submerging a "Seed plate" of metal in a hydrocarbon, then bringing the hydrocarbon near it's decomposition temperature, then letting the carbon deposit itself onto the "Seed plate" then removing the metallic plate once the desired thickness has formed.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> How is Pyrolytic carbon different from graphene foam?
> 
> They are both formed by submerging a "Seed plate" of metal in a hydrocarbon, then bringing the hydrocarbon near it's decomposition temperature, then letting the carbon deposit itself onto the "Seed plate" then removing the metallic plate once the desired thickness has formed.


I've no idea?...lol...Just thought they must be different.....I mean foam is a a 3d mesh of bubbles....but this pyrolitc graphite as I understand it is many planar sheets laid one on the other......but if there is no difference I stand corrected.

In any event there is no heat sink and no clamping pressure to be concerned with....just the sheet stuck to the IHS via it's own pre-applied 10micron acrylic adhesive layer.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I've no idea?...lol...Just thought they must be different.....I mean foam is a a 3d mesh of bubbles....but this pyrolitc graphite as I understand it is many planar sheets laid one on the other......but if there is no difference I stand corrected.
> 
> In any event there is no heat sink and no clamping pressure to be concerned with....just the sheet stuck to the IHS via it's own pre-applied 10micron acrylic adhesive layer.


The more I research, the more it's perceived to be two different products. The more I research it, the more it looks to be the same thing. I'm grinding my head in circles trying to find the difference.









(Note: Graphene foam isn't a 3D mesh of bubbles. It get's it's name because of the aesthetic view of how the atoms bond. .)



There was actually some research done that showed graphene is impermeable to fluids, so despite how it looks it does not have any gaseous bubbles in it. It it was theorized that vacuum sealed graphene foam balls could be developed, which would be lighter than air.
http://www.itsnerve.com/news/Graphene/

It's a cool read.


----------



## technogiant

Interesting stuff......but either way there should no problem.....the material is flexible and can be bent and re-bent repeatedly....and no clamping pressure to squash it anyway so all good.


----------



## technogiant

doubler


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Interesting stuff......but either way there should no problem.....the material is flexible and can be bent and re-bent repeatedly....and no clamping pressure to squash it anyway so all good.


This is true.


----------



## ZytheEKS

It's a shame TEC Peltier blocks have a minimum operating temp. If you were able to slap one of those on the IHS, and run a 400Qmax one at 24 volts, 30 amps you'd be able to create a heat vacuum in addition to creating a larger potential surface area. Of course then you'd have to deal with TIMs again.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> It's a shame TEC Peltier blocks have a minimum operating temp. If you were able to slap one of those on the IHS, and run a 400Qmax one at 24 volts, 30 amps you'd be able to create a heat vacuum in addition to creating a larger potential surface area. Of course then you'd have to deal with TIMs again.


Plus the added heat load of a quad tec unit destroying my chamber temps.....already thought along that route...thanks but no thanks.


----------



## RnRollie

Quote:


> Originally Posted by *ZytheEKS*
> 
> The more I research, the more it's perceived to be two different products. The more I research it, the more it looks to be the same thing. I'm grinding my head in circles trying to find the difference.


Maybe because they are so closely related?
They are both carbon lifeforms (its life Jim, but not as we know it Captain).. eh, carbon manifestations.
Whereas graph*ite* occurs in the wild, graph*ene* is the lovechild of graphite & a mad professor









AFAIK, the panasonic procedure creates graph*ite* sheets which act as a 'special' IHS by transporting the heat away from the source to the edges of the sheet (hence the application in mobile phones - transporting the heat to the enclosure); and would therefore be a terrible TIM. As it actually blocks the heat from going straight up/through.

Graphene foam is intended for other applications, i think









But, it is very well possible that the seeding procedure is the same.
Don't know how "public" the procedure is, or if Panasonic keeps some trade secrets on the procedure.

@techno
Actually, maybe iso folding cupcakes out of the sheet, maybe using it as a strip to carry the heat away to the box walls might be an idea. Make the box into a large thermal buffer. Thou, probably those strips would be too fragile.

.


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> @techno
> Actually, maybe iso folding cupcakes out of the sheet, maybe using it as a strip to carry the heat away to the box walls might be an idea. Make the box into a large thermal buffer. Thou, probably those strips would be too fragile.
> 
> .


Perhaps not quite cup cake cases but yeah you have the general idea.....no need to try and extend the graphite sheet to the box....it would be too far to be an efficient form of heat transfer...and there's no need when there' s 20 liters of liquid butane surrounding the cpu at -20 to -30c....ain't that enough buffering for ya?
Quote:


> Originally Posted by *RnRollie*
> 
> AFAIK, the panasonic procedure creates graph*ite* sheets which act as a 'special' IHS by transporting the heat away from the source to the edges of the sheet (hence the application in mobile phones - transporting the heat to the enclosure); and would therefore be a terrible TIM. As it actually blocks the heat from going straight up/through.


Although I'm not using this as a TIM and you are right that it is not intended for this use, none the less the heat tranfer along that perpendicular plane is not absolutely terrible at 10 - 26 w/m/k......its actually comparable to a very good TIM in that respect.

This straight up/down transportation is still however important, the heat doesn't actually come out of the edges....even if it did say that in the semi accurate article...I'd like to see how they make an edge connection to the 10 micron sheet edge...lol.

The way it works is that the huge lateral conduction spreads the heat over a large area which then dissipates in the more poorly conducting direction vertically through the surfaces, but because of the large area the heat becomes spread over then the poorer vertical conductivity makes little difference as the total heat transferred depends on the conductivity the heat gradient and the AREA of the transfer interface, so all those unit areas each with 10 -26 w/m/k add up to a lot of heat transfer.

My main concern with using this is actually that the lateral conduction will not be enough, because just like we have to consider the AREA of the surface you also have to consider the cross sectional area of the film as even though it has large conductivity it has very little thickness......as its 70microns and has about 2.5X the conductivity of copper then it would be like using a 70x2.5 = 175 micron or 0.175mm thick copper sheet to conduct the heat laterally.

From my understanding of studies on water blocks there is an optimal thickness for the base plate, too thick and it doesn't transfer heat well and too thin and it doesn't distribute the heat adequately.

It is this latter scenario I fear may be the case....but again that is why it is important not to disregard the vertical heat dissipation....as stated it has the same conductivity as a good TIM in this direction so I'm hoping that an equivalent amount of heat that would normally be passed into a heat sink will just pass vertically up and be dissipated into the liquid, this is actually crucial that this happens (and I'm making the assumption here that the IHS actually spreads the heat well over its entire surface?), any further dissipation from the fins I'm going to place over the center of the cpu and further dissipation from the sheet that extends beyond the IHS will really just be a bonus compared to what a standard heat sink would do.

It is experimental...just hope it works.








Think I've just wasted my money on this graphite sheet......although it may have great lateral conductivity if you start plugging in some figures to work out how much temp delta you get for a given heat energy input then it works out very poor.....simply because it is so thin it can't transfer much energy.......may look great on the demo's with an IR camera showing the heat spread but that doesn't show the quantity of energy being moved...just the temp distribution.


----------



## feznz

Quote:


> Originally Posted by *technogiant*
> 
> If this goes wrong you'll know.....It will register on the "Richter scale" even as far as NZ.
> but in case it doesn't it's Wales UK.....only a small country but full of fantastic minds....
> 
> 
> 
> 
> 
> 
> 
> 
> .


I thought all the brilliant minds left the UK on the first colonial ship that headed to NZ









and on the Richter scale we don't even talk about any under 5 seriously I live in Christchurch
http://www.christchurchquakemap.co.nz/all

As for the Graphite sheet I thought you were going to use it for a TIM to prevent washout with a server heat sink


----------



## technogiant

Quote:


> Originally Posted by *feznz*
> 
> I thought all the brilliant minds left the UK on the first colonial ship that headed to NZ


Nah that's just what we wanted you to think, the Welsh master race lives on,

http://imageshack.us/photo/my-images/94/8h5u.png/

Uploaded with ImageShack.us

As for the graphite sheet, well I wasn't intending to use it as a TIM I was going to use it as a heat spreader on its own....it's not actually meant to be a TIM.....but I wonder....it does have a similar thermal conductivity to good TIM in that plane, also I'd imagine it to be quite soft so clamping pressure would make it mold to any unevenness, may be a good idea, could even leave it untrimmed so it carries some of the heat out laterally.


----------



## RnRollie

suggest (again) to lap cpu & heatsink


----------



## mindblowingj

I don't want to be a bummer, but doesn't graphene need an extremely specific structure to act as a heatsink ? My understanding of the current setup makes it that the heat would be displaced around the edges of the graphene sheet, which would just move the heat elsewhere on the block resulting in very minimal help in dissipation. (but again it's my understanding and i'm in no way an expert)


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> suggest (again) to lap cpu & heatsink


Actually I've got to do a lot of modification to the heatsink anyway so will probably have a go at lapping


----------



## RnRollie

Quote:


> Originally Posted by *mindblowingj*
> 
> I don't want to be a bummer, but doesn't graphene need an extremely specific structure to act as a heatsink ? My understanding of the current setup makes it that the heat would be displaced around the edges of the graphene sheet, which would just move the heat elsewhere on the block resulting in very minimal help in dissipation. (but again it's my understanding and i'm in no way an expert)


Its graphite sheets, not graphene, but hey are family (see a few posts back), and the procedure to create super thermally conductive is roughly the same, you have to "grow/assemble" layer by layer to ensure it.


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> Actually I've got to do a lot of modification to the heatsink anyway so will probably have a go at lapping


unless you want to go the silk & toothpaste route, you could be done in +/- 1 hr (30 mins cpu, 30 mins for the hs/block)

Don't go ordering the exotic lapping kit from a specialists website for "only" 30 quid route... Halfords has all the stuff you need, except for the glass plate , but frankly, if you've got a decent kitchen counter or some marble slab , it 'll work fine


----------



## mindblowingj

My bad, I just took a look into the process, it's a lot less complex than what I had understood ! I wonder why we don't see more of those graphite HS's I'm looking into ordering one and experiment !


----------



## RnRollie

Quote:


> Originally Posted by *mindblowingj*
> 
> My bad, I just took a look into the process, it's a lot less complex than what I had understood ! I wonder why we don't see more of those graphite HS's I'm looking into ordering one and experiment !


get the thicker one, its more versatile (less fragile)


----------



## technogiant

Quote:


> Originally Posted by *mindblowingj*
> 
> My bad, I just took a look into the process, it's a lot less complex than what I had understood ! I wonder why we don't see more of those graphite HS's I'm looking into ordering one and experiment !


When you work out the temperature delta you would get for a heat load comparable to a powerful cpu its no good...because the sheets area very thin and have a tiny cross-sectional area the total amount of heat they can transfer is low......they are more suitable for lower powered applications....like mobile....which is what they were intended for......


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> unless you want to go the silk & toothpaste route, you could be done in +/- 1 hr (30 mins cpu, 30 mins for the hs/block)
> 
> Don't go ordering the exotic lapping kit from a specialists website for "only" 30 quid route... Halfords has all the stuff you need, except for the glass plate , but frankly, if you've got a decent kitchen counter or some marble slab , it 'll work fine


Thanks Rollie I will give that a go....I guess I'll still have to use a tiny amount of tim though even after lapping.


----------



## technogiant

Okay bad news, I've hit a potentially project stopping problem, I got all the gas fittings today, the flexi stainless steel hoses etc....I've been selecting the things to be compatible with a a 15kg calor butane cylinder which in the UK uses a 21mm clip on fitting.....trouble is the clip on adapter has a non return valve in it!!!

This kind of kills the entire project as I need to be able to return the liquid butane to the cylinder...which would be stopped by the non return valve









The adapter is completely sealed from what I can see so no way to remove the non return valve.









I may be able to get around this by using a propane cylinder and swap the gas out for butane. In the UK these propane cylinders have a standard tap valve fitting directly on the cylinder....I don't think these have a non return valve in them.

I can get an adapter so I can connect my butane hoses to the propane cylinder so that's not a problem (if only I'd know this at the start I could just gone for propane fitting and saved a lot of money on these adapters!!)

But my question before I spend more out on what is otherwise a dead project is does anyone know for sure whether or not these propane cylinder tap valves have a non return function?

I'm hoping not....I mean they do refill them somehow


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Okay bad news, I've hit a potentially project stopping problem, I got all the gas fittings today, the flexi stainless steel hoses etc....I've been selecting the things to be compatible with a a 15kg calor butane cylinder which in the UK uses a 21mm clip on fitting.....trouble is the clip on adapter has a non return valve in it!!!
> 
> This kind of kills the entire project as I need to be able to return the liquid butane to the cylinder...which would be stopped by the non return valve
> 
> 
> 
> 
> 
> 
> 
> 
> 
> The adapter is completely sealed from what I can see so no way to remove the non return valve.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I may be able to get around this by using a propane cylinder and swap the gas out for butane. In the UK these propane cylinders have a standard tap valve fitting directly on the cylinder....I don't think these have a non return valve in them.
> 
> I can get an adapter so I can connect my butane hoses to the propane cylinder so that's not a problem (if only I'd know this at the start I could just gone for propane fitting and saved a lot of money on these adapters!!)
> 
> But my question before I spend more out on what is otherwise a dead project is does anyone know for sure whether or not these propane cylinder tap valves have a non return function?
> 
> I'm hoping not....I mean they do refill them somehow


Couldn't you just install a second empty cylinder to the rig, then use a one way valve to empty the butane from the first cylinder to the chamber, then disconnect it?


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Couldn't you just install a second empty cylinder to the rig, then use a one way valve to empty the butane from the first cylinder to the chamber, then disconnect it?


Sorry don't understand....the secondary tank would also be connected via a non return valve and so be of no use....unless I'm misunderstanding your meaning?


----------



## technogiant

Okay.....I'm going to take a gamble on there not being a non return valve on these screw tap type gas cylinder valves....I have looked at a schematic before which I can't find again now and there was nothing of that nature that was obvious.....I'm just a little thrown by this as in addition to the clip on adapter having a non return valve also the hose extender adapter to join the two flexi hoses had one! But I was able to remove that one....just a bit unsure where else they may turn up.

I'm as sure as I can be these screw valves will not have one as of course they must refill these commercially somehow and I guess they must do that with the screw valve in place.

So....I've previously thought of a way to swap out the propane for butane as I was originally going to use a propane cylinder (because I was uncertain of the way those clip on connectors work....how right I was to be wary..... wish I'd stuck to my guns.... but it SEEMED easier to go straight for the butane...and WOULD have been if not for than non return valve!!)

So this is the procedure I'm intending to use which I'm throwing open for critique....firstly I'll burn off as much propane as possible, but of course the cylinder always contains some residual gas.

I'm thinking it may be difficult to make a low cylinder pressure to suck butane in as propane even at the lowest temp I can get with a domestic freezer still has a positive vapor pressure of about +2psi.

So I was thinking I'd have the propane cylinder and the butane cylinder attached to an expansion sac.

The butane cylinder would be closed and I'd open the propane cylinder, obviously not much would happen as there would be little pressure left in the propane cylinder. So I'd warm it, perhaps by placing in warm/hot water to cause the gas with in it to expand and be driven into into the sac.

I'd then evacuate the sac and refill it with butane then remove the propane cylinder from the heat source.

I guess that as the propane cools it will contract and draw a small amount of butane into the cylinder.

Once I have a small amount of butane in there I can then put the propane cylinder in a freezer and that small amount of butane will liquify causing a low pressure which will draw further butane in from the expansion sac which I can progressively top up from the butane cylinder.

Once I had a sufficient amount of butane liquid in there I could then remove it from the freezer and allow it to increase in temperature, as the butane boiled off it would purge off any remaining propane in a form of low temperature fractional distillation.


----------



## RnRollie

bad luck...

I imagine the nrv sits in the flying saucer pressure regulator and that any nrv valve in the cylinder/flask head is actually depending on pressure. iow for refill they use brute force pressure to force open the nrv. Unfortuantely, much more pressure as you can generate









So, screw safety features:

Put a brass T with ballvalve between the cylinder & the tap (with non-return valve).
Butane will still get to the chamber, but will have to return using a secondary line (hence the ballvalve & T)

Or find a Shell refill station (its Wales, so you ARE out in the country







and nick their refill mechanism









oh look: http://www.spiritburner.com/fusion/showtopic.php?fid/403/tid/27582/fbb_session_id/6ae75ed52c0e00656a9ee44f0a4e626a/


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> bad luck...
> 
> I imagine the nrv sits in the flying saucer pressure regulator and that any nrv valve in the cylinder/flask head is actually depending on pressure. iow for refill they use brute force pressure to force open the nrv. Unfortuantely, much more pressure as you can generate


There is no pressure regulator with the clip on adapter I've bought its all for the high pressure side....the adapter I've got is simply a clip on mechanism, ball valve and sadly nrv mechanism.

I'm not sure if there is a non return valve built into gas cylinder/flask heads.....the mechanism for the clip on type is a bit of an unknown as far as I'm concerned, and what I've seen of the screw valve fittings there is no nrv in the valve and can't be any in the flask head as it simply a tapered screw fitting.....so it should be alright with that type......if there is a pressurized nrv in the cylinder/flask head then I'm out......as you say I'd not generate the pressure to open that.....But having said that there can't be a pressurized nrv in there...if you think it out....it would be closed all the time unless as you say brute force opend by pressure from outside....but it would in normal operation be closed and not let gas passed for normal use...surely?.....I've been making a few phone calls to see if I can get a definitive answer on this, while I wasn't able to get that I did find out that often when cyliders are returned to the deport for refilling they are full of water, that sort of negates the idea of their being a nvr that requires pressure to override it.
Quote:


> Originally Posted by *RnRollie*
> 
> So, screw safety features:
> 
> Put a brass T with ballvalve between the cylinder & the tap (with non-return valve).
> Butane will still get to the chamber, but will have to return using a secondary line (hence the ballvalve & T)


Problem is the clip on and nrv are all in one solid unit which clips directly onto the cylinder.....so can't put a "T" section in there before the nrv.

Okay just found this video on youtube....kind of proof this can be done...at least with the screw valve propane type cylinder.....so no non return valve present there.






The valve he is releasing is the overpressure safety valve so he is basically allowing gas to be released and replaced by liquid.....so that's proof that these cylinders can be refilled by this sort of means ie no nrv.

But obviously he is doing it differently by releasing the safety overpressure valve to allow the vapor to be replaced by liquid.

Here's another video to show sort of proof of concept for doing it as I intend via a temperature pressure differential.






So it does all seem like this is doable....I'm a little concerned about the figures quoted in the end of this last video of what temp differential is required to get an optimal 80-90% fill.....that temp differential equates to about a 50psi filling pressure...no way I could do that...I'm looking at 8psi as just about a maximum...but again...if the tube is open and there is a pressure differential...then it will refill....surely?....of course what may be hampering their refill potential is that the small canister is actually being warmed by the incoming liquid propane which is at ambient temps...and the refill process they are using does generate an amount of heat via reversed phase change in the smaller bottle.....I'm guessing in the setup I'm using where the bottle is held at -20c in the freezer then fluid movement will go to completion.


----------



## RnRollie

my idea was to get a length of brass or copper (or even steel) pipe (a T actually ) , thread it on both ends so it can be screwed as an extention between the flask &nd the slip on adaptor (with nrv)... and screw the consequenses


----------



## ZytheEKS

Quote:


> Originally Posted by *RnRollie*
> 
> my idea was to get a length of brass or copper (or even steel) pipe (a T actually ) , thread it on both ends so it can be screwed as an extention between the flask &nd the slip on adaptor (with nrv)... and *screw the consequenses*


*two weeks later*

"In today's news an explosion from a computer being cooled by butane shook the Richter scales worrying the local geography stations for a time."










I had too


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> my idea was to get a length of brass or copper (or even steel) pipe (a T actually ) , thread it on both ends so it can be screwed as an extention between the flask &nd the slip on adaptor (with nrv)... and screw the consequenses


I understand...but you can't use a threaded connection to connect to this type of flask, it has a special push on/fit connection or clip on connection/mechanism.

The adapter has that type of mechanism but is all built in one solid sealed unit with the nvr......without that special connecting mechanism on one end you can't connect anything to this type of cylinder.
Quote:


> Originally Posted by *ZytheEKS*
> 
> *two weeks later*
> 
> "In today's news an explosion from a computer being cooled by butane shook the Richter scales worrying the local geography stations for a time."
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I had too


Oh don't, many a true word is spoken in jest....lol

Anyway, Rollie isn't suggesting anything more dangerous than my intended idea........hope that's not a bad thing... :-/


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I understand...but you can't use a threaded connection to connect to this type of flask, it has a special push on/fit connection or clip on connection/mechanism.
> 
> The adapter has that type of mechanism but is all built in one solid sealed unit with the nvr......without that special connecting mechanism on one end you can't connect anything to this type of cylinder.
> Oh don't, many a true word is spoken in jest....lol
> 
> Anyway, Rollie isn't suggesting anything more dangerous than my intended idea........hope that's not a bad thing... :-/


Oh I know, and you've taken more then enough precautions IMHO, but the phrases "So, screw safety features" and "Screw the consequences" was just too precious of a setup for a joke to pass on. XD

Just thought of something that may be relevant. Couldn't you just drill a hole in an empty cylinder, and install your own fitting, then fill that cylinder effectively bypassing any pre-installed valves, etc.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Oh I know, and you've taken more then enough precautions IMHO,


I hope you're right on that...


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I hope you're right on that...


Be sure to keep a C02 fire extinguisher around though, just in case.









(Obviously you wouldn't want a chem foam, or water extinguisher as it would assure the destruction of all the electronics.)


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> I understand...but you can't use a threaded connection to connect to this type of flask, it has a special push on/fit connection or clip on connection/mechanism.
> 
> The adapter has that type of mechanism but is all built in one solid sealed unit with the nvr......without that special connecting mechanism on one end you can't connect anything to this type of cylinder.


Ah well, i haven't had a good look on these things lately,... i cant remember the valve/header being welded into the flask...
maybe i'm mixing up butane, propane, LPG, beer-keg, thermos-flask (hmmm ice-tea)

As for fire... keep a bottle of O2 & mask on your person at all times... in case of fire, flood the room/house with Halon (or CO2)









Something else... not sure how you are going to proceed on the CPU heatsink matter, but i might have an idea... let me make some sketches and i'll get back on it


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> Ah well, i haven't had a good look on these things lately,... i cant remember the valve/header being welded into the flask...
> maybe i'm mixing up butane, propane, LPG, beer-keg, thermos-flask (hmmm ice-tea)
> 
> As for fire... keep a bottle of O2 & mask on your person at all times... in case of fire, flood the room/house with Halon (or CO2)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Something else... not sure how you are going to proceed on the CPU heatsink matter, but i might have an idea... let me make some sketches and i'll get back on it


Yeah funnily enough I was originally intending to use a liquid used in fire extinguishing...FM200.
But it would cost £360 per bottle and I would need two of them :-/ still if this works out I may well bite the bullet and swap out the cooling liquid for something safer like that.

Hey and great...all suggestions welcome...thanks for taking the time......I've been experimenting with my custom TIM..syrup and alumina 10 micro powder (will exchange for diamond dust 15 micron in final mix)...actually working just as well as my current TIM which compared to artic silver 5......so not bad for a home brew....was burning intel burn test all yesterday evening with it and holding up well so far.....but will continue testing.


----------



## RnRollie

So, you've got this box, tray, chamber with liquid butane a few mm to a few inches "deep". At the surface you've got a boil-off layer.

pic1


So, if i introduce a hollow J-pipe in there, i basically have a thermosiphon since boiloff will still occur in the pipe, causing "fresh" liquid to be "sucked in" at the bottom/submerged part.

pic2


So, the most basic design _(harking back to the days where we still had to mill or own waterblocks)_ for a CPU block is a copper plate with a copper J tube soldered on. Where the submerged end points to the coolest spot you can find around the CPU, and the chimney "straight up" above the hot core.

Of course, that is maybe a bit too simple









Top sketch (see picture below)
1 - Copper plate
2 - Copper J- tube

Given enough load & time, eventually, the whole copper plate will heat up, and thus the copper tube also... at some point you risk getting boiloff at the submerged sucktion end. Which will most likely collapse the thermosiphon function/performance. The chance of this happening can be calculated apparently









But why impose a limited operation & temperature range? Why not avoid boiloff at the wrong place/time?

Ideally, you get some block milled out of delrin or something (or cast out of unobtanium).

Basically an open block which serves as a mechanism to keep a copper plate & chimney in place and provides for a mounting mechanism on the CPU.

Middle & bottom sketch (see picture below)
1. delrin "open" block
2. copper baseplate (act as a lid on the block)
3. open inlet side
4. drilled & tapped G 1/4

Screw a barb or threaded piece of pipe in the G1/4 for the chimney
Bolt down the whole contraption with a "standard" waterblock mounting system and there you go: thermosiphon spot cooling



Of course, it will probably pay to look around... find a (really) old Waterblock or universal GPU block or north/southbridge block and modify accordingly.

My best guess is that the universal GPU block is best suited for modding -something like a swiftech MCW82 or an Evercool 201
http://www.performance-pcs.com/catalog/index.php?main_page=product_info&cPath=59_971_240_585&products_id=2110

So, whadda you think?


----------



## technogiant

Hey Rollie thanks for going to all that trouble there.....I've got to admit I'm trying to hang on to your shirt tails with this design...so if I'm understanding it the copper plate is placed on top of the cpu with a derlin enclosure around it open at one end and having a chimney at the other which vents above the liquid surface.

It would be quite easy to accommodate a design like this to go with the "de-fined" server cooler which will essentially be a flat copper plate....but you're leaving me behind a bit there....I'm not really sure what the purpose of the design is?.......is it to use the generated heat to cause a fluid flow?...whats the principle by which it works?


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> Hey Rollie thanks for going to all that trouble there.....I've got to admit I'm trying to hang on to your shirt tails with this design...so if I'm understanding it the copper plate is placed on top of the cpu with a derlin enclosure around it open at one end and having a chimney at the other which vents above the liquid surface.
> 
> It would be quite easy to accommodate a design like this to go with the "de-fined" server cooler which will essentially be a flat copper plate....but you're leaving me behind a bit there....I'm not really sure what the purpose of the design is?.......is it to use the generated heat to cause a fluid flow?...whats the principle by which it works?


Its a thermosiphon
http://en.wikipedia.org/wiki/Thermosiphon

As the liquid boils off in the "chimey" -induced by the hot cpu plate... it "sucks in" liquid butane at the bottom... you have now a CPU cooler which cools/works by convection; it ensures a constant liquid flow over the cpu.

It works like a waterblock, but without any moving parts like a pump









it should be more efficient (and lighter) as a huge chunk of copper. then again, a chunk of copper might work as well








but the siphon will get rid of more of the heat faster compared to a simple block which has to "warm up" before becoming efficient and has an upper limit. the siphin can do more, faster


----------



## technogiant

It's an interesting concept Rollie....and I'm trying to square it with the cooling method that the chamber uses...that is a submersion phase change method that relies on passive removal of the gas generated...it's not a method that relies on liquid flow as a primary means of cooling but it can assist when the heat density of the components gets too big.

On the negative side of this idea I'd be concerned that the enclosure would prevent the free release of gas and perhaps reduce efficiency.

On the positive side the flow it causes could help to remove the generated gas and so increase the heat density that (passive) submersion phase change is limited by.

So I've conflicting thoughts there and I suppose it depends on how those two features balance out.

I guess it could be designed to minimize the negative effects...perhaps by having a large volume enclosure.

I also wonder if it would actually increase the total flow.....I mean It creates DIRECTIONAL flow...but does it actually create any more flow than occurs with the uncovered copper plate where liquid flows from all directions to replace the gas that has bubbled off....... having said that I suppose a directional flow in the same direction that the bubbles are moving would assist in that respect.....uhhhm certainly food for thought.

PS...I've been thinking how exactly the flow will occur here, I think fluid movement will be more driven by the vapor production than by convection currents in the fluid.......in fact the vapor production will i think mix up the fluid up and so disrupt convectional movement.

If you consider what happens at the surface of the cpu contained in such an enclose/chimney assembly then when a bubble is instantly produced it will displace fluid, fluid will both be pushed out of the bottom of the chamber at the same time the height of fluid in the chimney will be pushed up, so the flow will be equal in opposite directions equivalent to half the volume of the bubble in each direction.

The bubble will then pass up the chimney, it will not make the fluid move it will just rise up through it. At the same time the head that was produced in the chimney will flow back against the direction the bubble is moving and so impede it.
This will mean that in total the volume of the bubble will have flowed out of the bottom of the chamber in the opposite direction of travel to the bubble.

When the bubble reaches the top of the chimney it will burst making a lower pressure head in the chimney equal to the volume of the bubble which will then be equalized by flow of equal volume to the bubble from the base upwards.

So in all there would be no net movement of fluid (only a small amount that may be dragged along by the bubble movement due to viscosity)...there would just be an oscillation of the fluid equal to the volume of the bubble firstly downward and then upward....put this together with many bubbles being produced simultaneously then I see that even these oscillations would be equaled out as they are not synchronous and would result in nil fluid movement.


----------



## RnRollie

Your butane is circulating anyways, changing from liquid to vapour over a large surface. The boiloff is unevenly distributed , you'll get more/faster boiloff over the hot spots.

What this siphon does is control/accelerate the boiloff process at a given spot INSIDE the environment. It forces (extra) convection in the liquid (and movement in the vapour/gas) in what would otherwise be a passive (vertical) circulation in the liquid & gas.
As far as the siphon is concerned it is living on the surface of Neptune or Pluto, the world outside the box does not exists.
The only "outside" influence is gravity, but that is conform for the whole chamber .







So, whatever it does, does not violate the laws of the environment it is in, it adheres to the laws which apply in the box, it is in balance with the milieu in the box.

whew, almost doing metaphysics here









anyways, need to run some numbers on it of course, but gut feeling says a 10-15% overall efficiency increase at virtually no cost

Note: come to think of it... just putting an upturned funnel/cone/cylinder over the heatsink/plate with 5-10mm open space between funnel and plate _(see picture)_ should have similar effect as long as its top end "sticks out" of the liquid. It should create a natural updraft, and thus accelerate the gas bubbles thus creating a flow in the liquid. Working like a real chimney stack











http://en.wikipedia.org/wiki/Stack_effect
http://en.wikipedia.org/wiki/Solar_updraft_tower
http://en.wikipedia.org/wiki/Cooling_tower


----------



## technogiant

It's interesting stuff and I've been reading through those links you provided.....

I'm not sure if the model for this buoyancy driven circulation actually fits as it requires the same medium either gas or fluid to be both inside and outside the "building" or in our case the chimney, in those circumstance the buoyancy effect causes circulatory flow between the outside and the inside.

But this is not the situation in the chamber, there will be liquid inside the chimney and gas outside and as you cannot get flow between the liquid and gas this cycle is essentially broken.

The only flow that would occur would be of fluid replacing that which had boiled off...which is an insignificant amount as only 4ml/s is required to cool 1kw.

The stack effect...ie causing a lower pressure inside the bottom of the stack when compared to the outside may have an effect though.....but not on flow of liquid which wouldn't be drawn up and out of the top of the chimney but it may draw up a small head so reducing the pressure in the liquid contained in the chimney there by lowering its boiling point.....but TBH my guess is that effect would be really minimal.


----------



## RnRollie

the chimney exhaust has to placed (well) above the liquid level. It ill suck in liquid at the bottom which will boil off because of the hot CPU/place and the vapour is exhausted throught the chimney

If the design & implementation is right you'ld be amazed about the the extra ooomphh it gives









Anyways... just to leap ahead... have any ideas about the final finish when it all comes together? I mean are you going to buff up all the visible parts to a chrome like finish? OR bring out the hammerite to get a "bronze" - steampunk look ?
Just something to think about when not solving the technical issues


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> the chimney exhaust has to placed (well) above the liquid level. It ill suck in liquid at the bottom which will boil off because of the hot CPU/place and the vapour is exhausted throught the chimney


This is where the idea falls down........the chimney will not suck in any more liquid than is being boiled off...it cannot...other wise an increasingly large pressure head of liquid would develop inside the chimney its level being higher than the surrounding submersion fluid......granted the "stack effect" will cause a small pressure head due to suction but once the suction is balanced by the pressure head then the only flow of liquid will be that which replaces what is boiled off..... ie... no increased flow beyond what is normal....at 1kw heat load the flow will only be 4ml/s....liquid flow is not important to this cooling method.

The only effect the lower pressure would have would be to drop the boiling point of the liquid.......but........really.....I don't think the suction produced would be of any significance at all.....if it were to drop the pressure by 1psi then it would have to draw a column of butane liquid up the chimney 1.25 meters higher than the level of that in the chamber and firstly the chamber isn't even going to be that high, secondly I've no idea how high the chimney would have to be to maintain a 1.25M column and lastly and most importantly we know from every day experience that the effect produced is not going to be anywhere near as pronounced as this....just venting off at max a liter of gas per second is not going to draw much if any liquid up the chimney...certainly not enough to be of significance......just imagine putting a one end of a tube in a bowl of water then getting a smaller pipe putting that in the bottom of the tube under the water line and blowing through it.....nothing of any significance would occur other than bubbles going up the tube.....there would not be any noticeable rise in water up the tube....like I said sadly an insignificant effect.
Quote:


> Originally Posted by *RnRollie*
> 
> Anyways... just to leap ahead... have any ideas about the final finish when it all comes together? I mean are you going to buff up all the visible parts to a chrome like finish? OR bring out the hammerite to get a "bronze" - steampunk look ?
> Just something to think about when not solving the technical issues


As with most things I do the final finish will lean heavily towards Ghetto...lol

Not too concerned really...the outer case will be insulation board so not too much you can do to make that look nice.....just bought a section of toilet waste pipe with a 90 degree bent which will be the secondary submersion chamber for my cable connections....so not a lot more to be said on that :-/ .....gas pipes, toilet waste pipes, insulation board and a collapsible water container (purging sac) are hard to make look good......just hoping the performance makes up for it....lol.


----------



## technogiant

Well today I've been cutting the holes to run the cables through.....I've been sort of reluctant to do it ....you know cutting holes in my supposedly gas tight chamber sort of went against the grain....but still done now.....I'll start sealing the cables in there tomorrow.

I want to get a better web-cam to put in the chamber as well.....so I can see whats going on in there...I need to be able to see the liquid levels when I'm filling the chamber...and I want to see the phase change of liquid butane in action together with the filling and emptying action of the chamber basin...kind of excited about that.....so I'll pick one up at the local pc world or curry's to save waiting for delivery.......I want to push on now....too much thinking about what will and won't work...just want to finish this and test in real world rather than theoretical.

Another nice little time killer has been stripping all the outer braiding off all the power cables.....the 24 wire atx cable, additonal 12v and pcie cables....hours of "fun"?!!..spend several evenings in front of tv doing that....still again all done now.

Tomorrow sealing the cables in and fixing the gas pipes in there.


----------



## RnRollie

i assume you're going to put the webcam connectors on the OUTSIDE of the box? To connect to another pc/tablet?

cause...
1. if its plugged into the MB inside the chamber, that means running the MB without cooling to see whats going on while filling... doesn't see like a good idea

2. if its the wireless variant... how you overcome the faraday cage you've created? 15mm alu is way more as the walls of a microwave and those do not let any get out (or any radiowaves in)

3. maybe most important... isn't it kinda DARK inthere?
An I.R. cam -unless mil-spec- has troubles "seeing" clear details through a cold mist. Of course, you can plug in a led strip or cfl... which kinda has to be external (another hole) or battery powered (battery soon dead at those minus temps); as running a few ledlight/strips of PSU molex or MB header brings you back to 1.

Somehow a big chunk of plexi as a viewport seems like an easier solution
















Sorry, just being my annoying self


----------



## technogiant

Hey not at all annoying Rollie....all good valid points.....I was steering away from the chunk of plexiglass viewing port as I'm trying to keep holes made in the chamber to a minimum....but if the web-cam gives up the ghost in the harsh chamber environment then that's plan B.....but I did really want to use a web cam so I can share video of it operating with you all.

Yeah I was planning on using a laptop to plug the cam into and getting one of those cams with several led lights so I can peer through Neptune's atmosphere.

IDK if I'll need more lighting than that but if so I can run those off the secondary power supply unit.....I have to run independent power in there so I can run the circulation fans prior to start up anyway.

I may not have to monitor the fill process once up and running as I'll have exactly the right amount of liquid in the bottle to fill the basin.....so long as I know when the liquid transfer has finished, perhaps by timing it.....I'd be able to remove the lap top and use the main pc for the web cam......Kind of like the idea of having a picture in picture of my system bubbling away whilst doing stuff...exciting in a sad geek sort of way.

What would be really good is doing this with an all glass double walled build so you wouldn't need any insulation....now that would look fantastic.


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> ---snip---
> What would be really good is doing this with an all glass double walled build so you wouldn't need any insulation....now that would look fantastic.


i LIKE that idea









Next time one of these types driving a white van with expired tax disk comes a-knocking at the door to sell you a triple glazed conservatory, you should bring it up









Actually, some trade fairs and showrooms have those reduced "models" of double & triple paned windows... should try to talk them into parting with those


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> *snip*
> What would be really good is doing this with an all glass double walled build so you wouldn't need any insulation....now that would look fantastic.


You'd basically be building a glass dewar then? You'd need some pretty darn thick glass to take the pressure I'd imagine.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> You'd basically be building a glass dewar then? You'd need some pretty darn thick glass to take the pressure I'd imagine.


Yeah I'd really like to make a sort of show case build like that...my builds so far have been rough and ready more concerned with performance than looks.

perhaps one day......I am thinking of evolutions of this for future builds if it works.....using a safe low pressure refrigerant that can be left in the chamber at ambient temps and so used in the house without a freezer to recover the refrigerant each time.......using the chamber directly as the evaporator so it can be made much smaller and using a split type ac unit so the compressor is outside....May be be possible to get the box down to one cubic foot.....now a glass version of that would be nice.


----------



## RnRollie

Quote:


> Originally Posted by *ZytheEKS*
> 
> You'd basically be building a glass dewar then? You'd need some pretty darn thick glass to take the pressure I'd imagine.


A "glass" pyramid should be able to should deal with it better as a "box"


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> A "glass" pyramid should be able to should deal with it better as a "box"


Now that would be showy.


----------



## RnRollie

if want showy , just something which looks like these:


 

With the installed MB at an angle

A converted A/C evap in a res in the pedestal + a pump in the res ; a showerhead/sprinkler in the top AND circulating cooled Fluorinert









A mini-Cray


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> if want showy , just something which looks like these:
> 
> 
> 
> 
> With the installed MB at an angle
> 
> A converted A/C evap in a res in the pedestal + a pump in the res ; a showerhead/sprinkler in the top AND circulating cooled Fluorinert
> 
> 
> 
> 
> 
> 
> 
> 
> 
> A mini-Cray


Funny as it may seem....these bear absolutely no resembles to my build WHAT SO EVER!!...lol.....one day when I'm rich.


----------



## technogiant

Okay just received my connector/adaptor to connect the butane stainless steel hoses to the propane bottle.....and thank goodness no non return valve....so still all systems go.

I've sealed all the cables through the chamber wall and tested....have just found a very small leak....so will have to track that down and seal it...but it's nothing major and would be sealed by the fluid in the secondary chamber any way....but will seal it non the less.

After much agonizing about the substance I'm going to put in the secondary chamber I think I've finally decided.....I've found a paraffin wax based body moisturizer that is thick at normal temps and freezes at sub zero temps....from the tests I've done it appears non conductive...I've tried it on both 12v power cables and sata signal cables connections and it appears fine...certainly no adverse affects on function and no discoloration or bubble formation I'd expect if there was any reaction going on with the metals.

So next stage will be drilling the gas pipe holes, slot to accept the evap pipes and then I'll be assembling the box.....working tomorrow and have some commitments but hopefully the box will be done by the end of the weekend.


----------



## technogiant

Just updating to say there's no update at the moment but I'm still alive and kicking......build has stalled atm.....I've been looking for something suitable to fix that small leak....trouble is with so many cables passing through the wall in a small area and all the sealant goop I've used it's impossible to know exactly where the leak is.....so I've been looking for something I can flood it with....I've found a flexible setting polyurethane resin which I've ordered but the supplier wasn't very forthcoming with details of the hardener I'd need to use with it....in the end I was assured it would come supplied with the hardener....uhmmm...I'm not convinced but will be receiving it soon and will know for sure....just hope it does and I don't have to wait further to sort this out.
I'll just temporarily put a section of pipe on the inside around the cables to act as a mold and pour the resin in to seal it.

http://uk.farnell.com/pro-power/ppc180/resin-pu-flexible-tough-low-visc/dp/1784618?Ntt=ppc180


----------



## mindblowingj

Nice to get some updates, keep it up.


----------



## technogiant

Quote:


> Originally Posted by *mindblowingj*
> 
> Nice to get some updates, keep it up.


Cheers MB.

I've got the poly U resin + hardener today together with the Poly U sealants I ordered......also got a good time off so should be making some real progress over the next week......glad to get this back on the road


----------



## technogiant

Okay, so it's been taking a while to do things, just sticking a bit at a time and allowing it to cure before going onto the next bit. Also my time hasn't been as uncommitted as I'd hoped it would be but I've assembled the box and re sealed the cables with polyurethane encapsulation resin. All looks fine and I've filled the chamber with water to do a leak test...that was 90 minutes ago and no signs of any leakage....but I'll leave it overnight to be sure.

Next stage I'm going to seal over all the joints/seams internally with 90 degree aluminium angle strips as a belt and braces approach to prevent leakage (will also be sealing over the seams externally in the same way as a triple leak defense), then fix the basin in and seal around the edge of that to the chamber wall so as to prevent spillage into the chamber base, I'm going to have breather tubes running from the gas space underneath the basin into the upper part of the chamber so there can't be any pressure difference between them. Also the gas line leading from the purging sac into the chamber will enter underneath the basin, this will allow me to bottom fill with butane when purging the system, gas entering underneath the basin, through the breather tubes and into the upper chamber, this will displace any air which is less dense upwards and out of the purging line which exits at the top of the chamber.

That shouldn't take too long, the next stage will be dropping the evap inside the chamber, but before I can do that I'll have to build the stand to put it all on. The bottom of the ac unit evap has to be higher than the bottom of the chamber as it sits on top of the basin which is 15cm high, also the chamber will sit on 10cm of insulation board so in all allowing for the thickness of the alu plate the ac unit is going to have to stand some 26.5cm above the base board of the stand. I'm also going to put the freezer on the same stand which will all be on casters, so it's going to be quite a sizable construction altogether. Having said that it's only wood work and insulation board stuff....shouldn't take too long to do...just has to be done before I can finish the chamber so as to get everything into the right position.

But the real news is the chamber appears sealed and leak free, at least as much of it as I can test at this stage...all looking good









PS...chamber has now been left overnight full of water....no leakage


----------



## romphoneiu

good,it would be of a similar type, probably a 13.6kg one, not just a one use bottle.thanks


----------



## technogiant

Quote:


> Originally Posted by *romphoneiu*
> 
> good,it would be of a similar type, probably a 13.6kg one, not just a one use bottle.thanks


Yes I will be using a 13.6kg reusable propane cylinder, I believe it has exactly the same capacity as the 15kg butane cylinder.....containing 26 liters of liquid gas ....the weight difference is due to liquid propane being less dense than liquid butane.


----------



## technogiant

Just a further update....I've made the stand today....all seems to be lining up okay from what I can tell ATM.

I've some time off work so can get on hopefully, I'll fit the submersion basin tomorrow, then I'll be able seal in the evap and shroud around it and the fans.
After that I'm pretty much at the end game, I'll have to adapt a heat sink, assemble the pc within, seal the lid on the chamber and insulate the outside and its just about done.

I yet have to get a suitable freezer, butane, propane and nitrogen cylinders and several bits and pieces.....but approaching the final stages now.


----------



## feznz




----------



## technogiant

I've secured the basin in place and sealed with angle around the outer edge so I can't get any spillage going under the basin, I've also put a breather tube between the underside of the basin and the upper part of the chamber so there can't be any pressure build up under the basin.

This also allows me to purge the system from where the gas line enters under the basin at the bottom of the chamber through the breather into the upper part of the chamber and out through the exit line at the top of the chamber and ensures there can't be any pockets or areas that aren't being purged properly.

I've also sealed the evap in position and sealed the pipes through the chamber wall, that's all been curing overnight and today I'm going to seal the fans in position to the side of the evap and shroud them together to ensure they draw gas through the evap efficiently.

After that I've just got to do some soldering of the fan cables, led light cables and the power/reset/cmos switches....position the lights and camera and that will be the chamber interior basically completed.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I've secured the basin in place and sealed with angle around the outer edge so I can't get any spillage going under the basin, I've also put a breather tube between the underside of the basin and the upper part of the chamber so there can't be any pressure build up under the basin.
> 
> This also allows me to purge the system from where the gas line enters under the basin at the bottom of the chamber through the breather into the upper part of the chamber and out through the exit line at the top of the chamber and ensures there can't be any pockets or areas that aren't being purged properly.
> 
> I've also sealed the evap in position and sealed the pipes through the chamber wall, that's all been curing overnight and today I'm going to seal the fans in position to the side of the evap and shroud them together to ensure they draw gas through the evap efficiently.
> 
> After that I've just got to do some soldering of the fan cables, led light cables and the power/reset/cmos switches....position the lights and camera and that will be the chamber interior basically completed.


So close to seeing performance numbers, yet so far. XD I'm stoked to see what kinda numbers it actually gets. Theoretical measurements and calculations are good, but there's something about benchmarks that's just so intoxicating.

Stoked to see the final product; keep up the good work.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> So close to seeing performance numbers, yet so far. XD I'm stoked to see what kinda numbers it actually gets. Theoretical measurements and calculations are good, but there's something about benchmarks that's just so intoxicating.
> 
> Stoked to see the final product; keep up the good work.


Cheers Zythe, yeah I'm getting pretty excited about that too, I'm basing my hopes on results I've seen from a Novec 3M 7000 build which basically is a similar submersion/phase change cooling set up....their cpu temps were as I recall only about 4 or 5 degrees C above the boiling point of the liquid underload.....but their boiling point was +37c.

The operating temp of my chamber and hopefully hence boiling point of my liquid should be -25c to -20c or there abouts...so if my load temps are just 4 or 5 degC above that I will be well pleased









But as you say this is all theoretical atm...just crossing fingers.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Cheers Zythe, yeah I'm getting pretty excited about that too, I'm basing my hopes on results I've seen from a Novec 3M 7000 build which basically is a similar submersion/phase change cooling set up....their cpu temps were as I recall only about 4 or 5 degrees C above the boiling point of the liquid underload.....but their boiling point was +37c.
> 
> The operating temp of my chamber and hopefully hence boiling point of my liquid should be -25c to -20c or there abouts...so if my load temps are just 4 or 5 degC above that I will be well pleased
> 
> 
> 
> 
> 
> 
> 
> 
> 
> But as you say this is all theoretical atm...just crossing fingers.


I saw that build. Novec 7000 also has a freezing point of -120









It's a damn shame Novec 7000 is so flippin' expensive, or I could see SO many uses for it in the high performance cooling market.


----------



## mindblowingj

Quote:


> Originally Posted by *ZytheEKS*
> 
> I saw that build. Novec 7000 also has a freezing point of -120
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It's a damn shame Novec 7000 is so flippin' expensive, or I could see SO many uses for it in the high performance cooling market.


I did read alot about fluorinert and novotec line of products as it is really interesting on paper, but following experiences from a few members I come to the realization the best you can do with it is just "pretty cool passive cooling"... such as 




This sums up much about it:
Quote:


> Originally Posted by *NoL*
> 
> I've used the original 3M solution.
> The end result is the cost and need to keep a sealed hermetic environment does not outweigh the benefits. Ultimately air cooled servers are more efficient and use less space in 1U rackmount configurations without the need for a condenser. Increasingly, for overclockers, it serves less purpose as it is not a good working fluid, and is prone to gelling. So you get water results at many times the price, difficulty, and encumberance.
> 
> It's fun and a cool idea. But also, insulation for sub zero methodologies has progressed incredibly in the last five years. Insulation is simple and does not place permanent marks upon motherboards and rarely results in damage with minimal preparation, something far from this configuration.
> 
> Sure is the power recoup nice? If you can produce high enough pressures for a regenerator, yes. Is it viable? Not really.
> Also the fluid is often used with masks, as the effects of the fluoroether long term on lung tissue is not yet known or tested.


----------



## ZytheEKS

Quote:


> Originally Posted by *mindblowingj*
> 
> I did read alot about fluorinert and novotec line of products as it is really interesting on paper, but following experiences from a few members I come to the realization the best you can do with it is just "pretty cool passive cooling"... such as
> 
> 
> 
> 
> This sums up much about it:


Well, it's a dielectric fluid, so in theory you could just pop in some fans like a normal air cooling chassis, then use an ultra low temp chiller. There's a whole mess of cool things you could do if it was readily available, but it's $300 for a gallon so your forced to try and use it with design that uses a VERY small amount of it, if you're able to do it at all.

\


----------



## technogiant

Yeah it was the cost of such fluids and other refrigerants that pushed me towards using butane, readily available and cheap...(just hope that decision doesn't cost more than money)....it's not just the original purchase price but the cost of purging the system and replacing gas every-time the chamber is opened....not to mention it could be a large expense wasted if things don't work out as I hope.

I must admit as my project progresses I am starting to wonder if the outcome is going to be worth the investment in time, money and for that matter if the "inconvenience/maintenance" of such a system will be worthwhile......but in those immortal words "I've started so I'll finish" I will see this through if for nothing more than proof of concept....I think ultimately I'd like to evolve the project further to use a low pressure refrigerant for the submersion fluid, one with a boiling point around ambient so that the liquid would not need to be recovered to a pressure bottle between uses. I'd also like to make a custom cooling unit not just use a window ac unit....but actually make a system where by the chamber was the evaporator with the suction and capillary line opening directly into it's vapor space...that together with a split system design so the noisy compressor could be house outside would I think be the ultimate goal of this project....but that is for the future.

As regards current progress I've just about completed the internals of the chamber, evap is shrouded in and fans fixed and wired to the controller as are the lights, camera also fixed in position. The stainless steel hose has also been sealed in through the chamber wall and all that remains is to fix the end of the SS hose into the bottom of the basin.

Today I've bought a 10 liter cylinder of oxygen free Nitrogen for purging the system of oxygen.....but that has brought further problems.....the connection with the cylinder on first inspection appeared to be the same as a standard propane fitting....but sadly it is not...the propane connector has an opposite thread direction.....so I may have to botch something up....also the bottle pressure is very high 300bar...I'll have to be careful I don't blow my purge sac to pieces or I may have to put a regulator in there...which seems a little excessive just to purge the system out....I'll just have to find a work around....but I'm working for the next week so will just have to leave it there for now.


----------



## mindblowingj

Hooray for updates !
About the N, it seems to me the only real problem is the format of the container's connection.. Isn't this something that would vary from a company to another ? I have been looking for a generic adapter/ extention hose with different ending but no real luck without knowing the name or part # of those connections =/ I'm sure someone more knowlegable about it could find one tho. It seems more simple than addind another part to the system.

Cant wait to see more of this ! keep it up


----------



## RnRollie

the reversed thread is on purpose to distinguish the difference between propane & butane, to make sure you dont use butane on a propane (heating) system & vice-versa... its like an ISO standard








There are double threaded conversion adapters , most likely even to be found a the local hardware store...
Use is very popular at trailer parks , however very much no-no; as when you blow up your trailer and they find out you've been "converting" your system the insurance company pulls its hands off.. plus a serious fine on top, and in some US states criminal charges.... blowing up your trailer because you've converted your system to a still or turning your trailer into a meth lab is one thing, but potentially flattening the whole trailer park is frowned upon.

Anyways, need a butane adaptor for the N


----------



## mindblowingj

Quote:


> Originally Posted by *RnRollie*
> 
> blowing up your trailer because you've converted your system to a still or turning your trailer into a meth lab is one thing, but potentially flattening the whole trailer park is frowned upon.


What a gem. ^^ made me smile


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> the reversed thread is on purpose to distinguish the difference between propane & butane, to make sure you dont use butane on a propane (heating) system & vice-versa... its like an ISO standard
> 
> 
> 
> 
> 
> 
> 
> 
> There are double threaded conversion adapters , most likely even to be found a the local hardware store...
> Use is very popular at trailer parks , however very much no-no; as when you blow up your trailer and they find out you've been "converting" your system the insurance company pulls its hands off.. plus a serious fine on top, and in some US states criminal charges.... blowing up your trailer because you've converted your system to a still or turning your trailer into a meth lab is one thing, but potentially flattening the whole trailer park is frowned upon.
> 
> Anyways, need a butane adaptor for the N


Lol...Hi Rollie...where have you been, I've been missing your gentle reassurance that things are going to work out fine....lol

I've been looking into this connector problem, it's quite easy to get converters from butane to propane systems...I already have one of those.

The problem I've run into now is finding a connection for the N cylinder......from the searching I've done it's apparent that most flammable gases use left hand threaded connectors while non flammable / inert gases have right handed threads....its to prevent people connecting the wrong cylinders.

Anyways I'm not looking specifically for a propane/butane connection to fit the N cylinder...it would just have saved me some problems if what I already have could have fitted.

I just want something I can connect a pipe to the N cylinder with.....trouble is the N connections are industrial and only thing I can find is a combined connector and regulator....didn't want to incur the extra expense of that as I only want to purge out the darn chamber with it......I have seen a connector /regulator for £25 so not the end of the world....I may have to get that as I'm a little concerned that anything I can just botch together would be blown apart by the high bottle pressure......Still thinking on this one.


----------



## RnRollie

what about drilling and threading yet another hole/port to match in one of the walls ?


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> what about drilling and threading yet another hole/port to match in one of the walls ?


I won't be connecting it directly to the chamber, I don't want to risk damaging it by allowing full bottle pressure directly in there.....the only bottle that will be directly connected to it will be the one kept in the freezer so its pressure will only ever be negative or very low.

The nitrogen and butane bottles that will be used for purging will be connected to a purging sac isolated from the chamber by a shutoff valve so I can purge the chamber at low pressure simply by squashing the purging sac like a bellows.

I think I'm just going to fix a large hose 1 1/4 inch over the N cylinder outlet with sealant and a jubilee clip.....I'll have to step down the hose to 8mm ID to connect to the purge sac....just hoping the step down wont cause too much of a back pressure and break the connection to the N cylinder.....It will be opening into an expandable sac but the reduction in hose ID may cause it to pop off......don't know, will just have to try it gently and see.

Ps tomorrow I'm getting my propane and butane cylinders...so things still moving along.


----------



## RnRollie

just had a readback...erm... 300 bar... that is +4300 psi
is that one of those cases that if you bolt this bottle to a Robin Reliant and then knock off the valve it will try to launch it into orbit?

I've got flashbacks of my dad inflating my FINA plastic dinghy at the petrol station... it went kinda FLOEPS completely inflated in a second or two.. and thats using like 4/5/6 maybe 10 bar pressure?

mymy, there is a picture forming in my mind of a convoluted contraption... beginning to look like one of thoose steampunk devices witha pletoria of manometers and balancing valves and wheels...
Only thing missing is a guy in a labcoat running from valve to valve while hysterically laughing









Talking about mad scientists.. the N is used to get rid of the oxygen in the chamber(s)... you knwo there is another way... controlled burnoff ... as the butane turns into gas you open a valve up top and light it


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> just had a readback...erm... 300 bar... that is +4300 psi
> is that one of those cases that if you bolt this bottle to a Robin Reliant and then knock off the valve it will try to launch it into orbit?


Yeah...its hell of a pressure.....I opened the valve momentarily and it let out quite a powerful burst of gas....I'm starting to think it will not be possible to release it in a way that won't cause damage without a regulator.
Quote:


> Originally Posted by *RnRollie*
> 
> ......Only thing missing is a guy in a labcoat running from valve to valve while hysterically laughing


That would be where I come in...how do know what I look like....are you stalking me...lol
Quote:


> Originally Posted by *RnRollie*
> 
> Talking about mad scientists.. the N is used to get rid of the oxygen in the chamber(s)... you know there is another way... controlled burnoff ... as the butane turns into gas you open a valve up top and light it


If I was to do this you would have to re-imagine your mad scientist but this time running around with all his hair singed off...it would flash back into the chamber and explode..lol....the idea is not to have oxygen baring air and butane in the chamber at the same time...this is because even in the absence of "obvious" ignition sources simple static discharge formed by the movement of electrically non conductive gases can easily cause ignition.

I'm thinking there's two possible routes to do this, either by using a large expansion sac to contain the nitrogen in at low pressure and purging from there or by getting a regulator....something like this:-

http://www.ebay.co.uk/itm/Nitrogen-Gas-Regulator-2-Gauge-0-10-Bar-Side-Entry-/170930636928?pt=LH_DefaultDomain_3&hash=item27cc428880

I have no idea what the low pressure connection on this unit is like, but think this would be the neatest solution and doesn't cost too much.


----------



## Butter Chicken

total cost...? so far


----------



## technogiant

Quote:


> Originally Posted by *Butter Chicken*
> 
> total cost...? so far


OOHHH don't go there...you're going to spoil my day....not for the faint hearted

I've not been keeping detailed records but here's a rough breakdown

Windows ac unit £300-£400 (but already had that from previous build)

15mm Aluminium plate £400 (but may have gone a little heavier than required there...time will tell)

Steel basin £20

assorted cables/extenders approx £70

adhesives/sealants/aluminium angle approx £100

wood for platform and castors £50

stainless steel gas hoses and other gas fittings approx £150

Nitrogen cylinder £33

Items yet to be bought....

freezer £250

propane/butane cylinders £120 (including bottle deposit)

Insulation board £50

Nitrogen regulator £25

I'm not even going to add all that up.....but you can add another £100 for sundries I've forgotten and at least £10,000 for blood/sweat tears/lost sleep.


----------



## Butter Chicken

ouch! ok we're already over a grand by the time I got to the castors...

I have a very simple basic idea for sub-zero immersion but can't seem to get anyone to tell me if it'll work or not according to their experience... which would total anywhere from $500 to $1000

it's an ugly idea, not for show really... but I guess it could be?

-nice build at any rate, I appreciate your post and effort... I am currently searching for ideas and experiments.


----------



## technogiant

Quote:


> Originally Posted by *Butter Chicken*
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I have a very simple basic idea for sub-zero immersion but can't seem to get anyone to tell me if it'll work or not according to their experience... which would total anywhere from $500 to $1000
> 
> it's an ugly idea, not for show really... but I guess it could be?


Please share...always up for discussion on cooling ideas.


----------



## Butter Chicken

http://www.overclock.net/t/1429680/sub-zero-aio-immersion/0_20

it'll work I tell ya!


----------



## technogiant

Okay so I've bought my propane and butane cylinders today.....cheaper than I thought only £60 for the two of them.....spent several hours burning off the propane as I only need the empty cylinder of that....man been burning off for hours with large 3 foot flame.....would hate to have all that stuff go bang in one go!!

As regards the N cylinder connection I've decided to go for a regulator....done a bit of inquiring and the below unit has a 5/8th inch BSP connection which is compatible with the N cylinder and on the low side outlet of the regulator there is a male 3/8th BSP connection which will allow connection to a 8mm hose via the below connector.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=170930636928

and

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=360702340105

Regulator allows for 1 - 10 bar regulated pressure so should be much more manageable.


----------



## technogiant

Hi all, looking for a bit of help here on this, I've got my heat sink today:-

http://www.akasa.co.uk/update.php?tpl=product/cpu.product.tpl&no=181&type=CPU%20coolers&type_sub=Low%20Profile&model=AK-CCE-7107BS

My initial intention was to remove the fan and cut all the fins off so I could coat it with as thin a coating of thermal adhesive as I could and then adhere aluminium oxide powder to it to promote nucleation.

The thinking behind that being that the fins may trap the bubbles generated and so insulate the heat sink, also special nucleation coating used in Novec 2 phase cooling actually increase cooling by a factor of x15.

But I'm starting to have second thoughts...I'm not sure I'd be able to make the coating thin enough and it may end up being counter productive.

I've taken the fan off the heat sink base, its a nice solid lump of copper measuring about 8.5cm X 8.5cm, the fins are about 8mm tall and spaced 1.5 to 2 mm apart.....I really don't think that there would be any problem with heat transfer having this lump of copper submerged in liquid at -25c....let alone the fact that liquid was also phase changing.

I'm thinking I may leave it as is...perhaps even leave the fan on there that draws in through the fins and pushed out through the side vent so would complement the natural movement of the gas generated....I know it would be submerged but the liquid is less viscous than water and only just over half the density of water so I guess it would cause enough agitation to remove any gas bubbles from nestling between the fins.

Just not sure of the best way to go...although now leaning towards leaving it as is with the fan in place.....would appreciate opinion on this.


----------



## feznz

Actually I think you are right I was looking at the Novec I couldn't find any real specifications on thermal conductivity and capacitance I was left wondering was it any better than the good old mineral oil
Leaving the fan on? only if I was running the fan to create circulation but I was wondering if good old convection is probably enough looking at LN2 pots


----------



## technogiant

Yeah the problem with the Novec build I saw was that they were using only the same surface area as the IHS of the cpu....just with a boiler plate with that special coating soldered to the IHS.

Looking through their documentation they say the max heat density is 6 to 10 watts/cm^2 before the bubbles start insulating the component surface. That's a problem considering the 2700k IHS only measures about 4x4 cm =16cm^2 or max heat output of 160 watts using their max figure....not really enough for a highly overclocked cpu.

So tbh you need to use a larger heat sink to distribute that heat over a larger area but you don't require anything like the area provided by all those fins...I'm just not sure if I'd get better performance by cutting off the fins so I can apply my version of the nucleation coating or by leaving them on and having a larger surface area but perhaps lowering the heat density that could be dealt with due to the bubbles not escaping so well....which may be overcome by the fan.....I'm probably agonizing over something that would make little difference but it's something I can't test prior to committing one way or the other.

As always it may be that a compromise will be best, perhaps I can thin the fins out perhaps by removing every other one.....that way the bubbles would not be trapped and I may be able to get in between them to apply the coating...I'd rather not use the fan if possible.


----------



## Butter Chicken

mineral oil is only good to -10 if even, I think you can achieve that kind of dial in with a good sub zero water chiller and antifreeze, with not much of a mess to clean...

- the copper heat sink is an excellent idea and was thinking the exact same thing myself when looking at novec and other engineered fluid immersed systems, but then I started thinking since they been there already and have a server running under the stuff, that 3M may have known something I didn't about leaving the IHS bare bones?

I was thinking a solid hunk of material like copper which was the same dimensions as the IHS soldered to it raising its profile at least a few inches... but maybe the solder job would have to be thin enough and sealed solid enough for no penetration of the liquid to occur between the IHS and its addition... that would definitely take machine work on both surfaces pre-solder.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> Hi all, looking for a bit of help here on this, I've got my heat sink today:-
> 
> http://www.akasa.co.uk/update.php?tpl=product/cpu.product.tpl&no=181&type=CPU%20coolers&type_sub=Low%20Profile&model=AK-CCE-7107BS
> 
> My initial intention was to remove the fan and cut all the fins off so I could coat it with as thin a coating of thermal adhesive as I could and then adhere aluminium oxide powder to it to promote nucleation.
> 
> The thinking behind that being that the fins may trap the bubbles generated and so insulate the heat sink, also special nucleation coating used in Novec 2 phase cooling actually increase cooling by a factor of x15.
> 
> But I'm starting to have second thoughts...I'm not sure I'd be able to make the coating thin enough and it may end up being counter productive.
> 
> I've taken the fan off the heat sink base, its a nice solid lump of copper measuring about 8.5cm X 8.5cm, the fins are about 8mm tall and spaced 1.5 to 2 mm apart.....I really don't think that there would be any problem with heat transfer having this lump of copper submerged in liquid at -25c....let alone the fact that liquid was also phase changing.
> 
> I'm thinking I may leave it as is...perhaps even leave the fan on there that draws in through the fins and pushed out through the side vent so would complement the natural movement of the gas generated....I know it would be submerged but the liquid is less viscous than water and only just over half the density of water so I guess it would cause enough agitation to remove any gas bubbles from nestling between the fins.
> 
> Just not sure of the best way to go...although now leaning towards leaving it as is with the fan in place.....would appreciate opinion on this.


Quote:


> Originally Posted by *technogiant*
> 
> Yeah the problem with the Novec build I saw was that they were using only the same surface area as the IHS of the cpu....just with a boiler plate with that special coating soldered to the IHS.
> 
> Looking through their documentation they say the max heat density is 6 to 10 watts/cm^2 before the bubbles start insulating the component surface. That's a problem considering the 2700k IHS only measures about 4x4 cm =16cm^2 or max heat output of 160 watts using their max figure....not really enough for a highly overclocked cpu.
> 
> So tbh you need to use a larger heat sink to distribute that heat over a larger area but you don't require anything like the area provided by all those fins...I'm just not sure if I'd get better performance by cutting off the fins so I can apply my version of the nucleation coating or by leaving them on and having a larger surface area but perhaps lowering the heat density that could be dealt with due to the bubbles not escaping so well....which may be overcome by the fan.....I'm probably agonizing over something that would make little difference but it's something I can't test prior to committing one way or the other.
> 
> As always it may be that a compromise will be best, perhaps I can thin the fins out perhaps by removing every other one.....that way the bubbles would not be trapped and I may be able to get in between them to apply the coating...I'd rather not use the fan if possible.


Just an idea, why not cut off the fins, and get a sand blaster gun that hooks into an air compressor. Then use a heat gun or a furnace to bring the copper block to a temperature where blasted material will stick. Then instead of sand fill the powder reservoir on the sand blaster gun with diamond dust. Then blast the copper block, now hot enough to promote material sticking, with diamond dust. It would be FAR more thermally conductive than the aluminum oxide, require no thermal adhesive, and have a MUCH more rough and bumpy surface to promote nucleation.


----------



## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Just an idea, why not cut off the fins, and get a sand blaster gun that hooks into an air compressor. Then use a heat gun or a furnace to bring the copper block to a temperature where blasted material will stick. Then instead of sand fill the powder reservoir on the sand blaster gun with diamond dust. Then blast the copper block, now hot enough to promote material sticking, with diamond dust. It would be FAR more thermally conductive than the aluminum oxide, require no thermal adhesive, and have a MUCH more rough and bumpy surface to promote nucleation.


I like the idea of getting closer to the metal with the conductive dust...but I guess I'd have to get the metal to the brink of melting point before the dust would stick in there....also the size of the dust that needs to be used is much smaller I believe than that used with a sand blaster at 10 microns, that apparently is the best size to use according to the Novec documentation...it doesn't act like a projectile but sort floats in the air like smoke when you disturb it.....I think this, although a nice idea, would be difficult to achieve.

I'm not sure having particles with extreme conductivity is necessary as the total area of heat transfer is quite large...also you are still limited by the max usable heat density of 6 - 10 watts/cm^2 so being able to transfer more than that by using highly conductive dust would then only be limited by the bubbles insulating the surface.

I need some means of applying a very thin coating of thermal adhesive, If there was something I could use as a thinner for the arctic alumina thermal epoxy I've bought that would evaporate off after I'd applied it, other than that I'm just going to have to apply it and scrape it off with a credit card or razor to get it as thin as possible.

Another idea may be to wet the surface with solder then remelt and apply the dust....but again may be difficult to achieve.


----------



## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I like the idea of getting closer to the metal with the conductive dust...but I guess I'd have to get the metal to the brink of melting point before the dust would stick in there....also the size of the dust that needs to be used is much smaller I believe than that used with a sand blaster at 10 microns, that apparently is the best size to use according to the Novec documentation...it doesn't act like a projectile but sort floats in the air like smoke when you disturb it.....I think this, although a nice idea, would be difficult to achieve.
> 
> I'm not sure having particles with extreme conductivity is necessary as the total area of heat transfer is quite large...also you are still limited by the max usable heat density of 6 - 10 watts/cm^2 so being able to transfer more than that by using highly conductive dust would then only be limited by the bubbles insulating the surface.
> 
> I need some means of applying a very thin coating of thermal adhesive, If there was something I could use as a thinner for the arctic alumina thermal epoxy I've bought that would evaporate off after I'd applied it, other than that I'm just going to have to apply it and scrape it off with a credit card or razor to get it as thin as possible.
> 
> Another idea may be to wet the surface with solder then remelt and apply the dust....but again may be difficult to achieve.


The solder idea sounds good. Personally I wouldn't trust an epoxy in this circumstance. They're thick, need a catalyst, can't be "reworked" so to speak, once it's on you can't retry as it's stuck to the heatsink so that means a new heatsink if you mess up. It would be MUCH easier to work with a solder, especially if you just heat the copper heatsink up to the solders melting point. Then you could achieve permanent contact, a nice rough and bumpy top, and a "reworkable" fail safe means of applying it.


----------



## technogiant

Hey Zythe I've just been having a practice with the thermal epoxy, it was actually not too bad to work with, just spread it out real thinly, dump a lot of powder on top and tamp it down with a flat ended object, let it set and then vacuum off the excess powder, I'll have a practice with solder as well but I anticipate there might be a problem with it running off the vertical surfaces of the fins when remelted...may be I'll do the base plate with solder first and the fins with the epoxy...still that's for experimentation tomorrow when I'll also be having my freezer delivered......once I've got that I'll be able to test out the cold line transfer procedure and hopefully transfer the butane into the empty propane cylinder, I've already managed to get a little of the liquid butane phase in there and purge off so that hopefully most of the propane has now been purged out.....but this will be make or break for the project....if the fluid transfer doesn't work then that's the end.

PS also had my Nitrogen regulator through...that all seems to fit together right and gives a manageable pressure...so things progressing nicely atm.


----------



## technogiant

Quote:


> Originally Posted by *Butter Chicken*
> 
> mineral oil is only good to -10 if even, I think you can achieve that kind of dial in with a good sub zero water chiller and antifreeze, with not much of a mess to clean...
> 
> - the copper heat sink is an excellent idea and was thinking the exact same thing myself when looking at novec and other engineered fluid immersed systems, but then I started thinking since they been there already and have a server running under the stuff, that 3M may have known something I didn't about leaving the IHS bare bones?
> 
> I was thinking a solid hunk of material like copper which was the same dimensions as the IHS soldered to it raising its profile at least a few inches... but maybe the solder job would have to be thin enough and sealed solid enough for no penetration of the liquid to occur between the IHS and its addition... that would definitely take machine work on both surfaces pre-solder.


Sorry BC only just saw your post......I think the difference with the server scenario is that the cpu's are not overclocked.....so the heat density on the IHS is well within the 6 to 10watts/cm^2 so nothing extra is required.

Also there is a problem using a heat sink in submersion systems as normal TIM will wash out.....so in all the servers are probably better off with the bare IHS.

As a TIM I'm either going to try Indigo extreme, I'd be a little reticent about soldering direct to the IHS as the high temps may damage it ....I also can't use other liquid metals as they contain gallium which could destroy my aluminium chamber.....but I'm a little concerned that the mounting method is a little hit and miss.....I don't want to have to crack open the chamber cos the TIM hasn't flowed properly and there's no way I could test before sealing it up.

I'm still strongly considering using my home brew TIM of syrup and alumina powder....its been working really well in a test rig I've been running......I would have the benefit that it would not dissolve chemically in the submersion liquid and from a mechanical stand point would be an extremely viscous almost solid at low temps and would therefore not wash out.

Of course that is bit of an unknown quantity also but it gave better temps that arctic silver 5 and showed no signs of drying out after a month of blitzing it with intel burn test and prime for long periods each day.


----------



## Butter Chicken

Quote:


> Originally Posted by *technogiant*
> 
> I'm still strongly considering using my home brew TIM of syrup and alumina powder....


make sure you use authentic Canadian Maple









wouldn't deliding the proc be safest method to attach the addition? but I guess after a delid resoldiering the IHS would be a little difficult...

as I have seen on delidded cpu's the chips is actually pretty small under there, so there is an air gap trapping heat in there unless the solder doesn't have a good seal and the fluid is allowed to enter the IHS.

my 2011 processor has this little hole in the top corner of the IHS and I've wondered if that it to allow the release of heat? other procs I seen without it.


----------



## RnRollie

about the HS, leave as is, with the fan

The effort of creating the ideal HS with controlled nucleation is way to big/complex to pay off.

Ideally you would have to "coat" each fin of the HS unevenly, providing more nucleation spots near the bottom while having a smoother surface near the top ... or vice-versa

The more nucleation spots, the more bubbles can form, but the more they "stick" to those points untill they become large enough to have sufficient "buoyance" the rip themselves loose.
Which is why each fin needs to be unevenly coated to facilitate this.

Imagine, for the sake of illustration, that each fin of the HS is 10 mm tall, and each mm differs one degree (bottom "hottest", top "coolest"), by controlling the nucleation points with variable "coating" you are actually optimising the HS for a certain temp "range". So, to work out the ideal coating, you need to find the ideal working range of the heat dissipation. Therefore you need to know how much heat you are going to produce... and when its all said and done you'll have to live with the possibility that the "tuned" dissipating range is smaller as the production range... unless you can produce an "oversized/overextended" dissipation range.
While it is true that the "coolest" point would be the nucleation point, the duration of the bubbleforming (till it breaks free) could actually be counterproductive.
In other words, in order to find the best HS nucleation range/setup, you'ld need to setup a lab with controlled variable conditions.... or do all the involved maths taking into account that a mathematical model does not always behave as it should in real life









Oh, and you'ld also have the shorten each 2nd fin to half (or 3/4 or 1/4) the height of the adjacent fin. To avoid bubbles being "trapped" for too long.

My suggestion is to use the HS with the squirrel fan to move (lotsa) liquid as the easier solution to start off with. Its range will be wider but less efficient.
Yes, it means that it will cool the CPU with liquid which is substantially "hotter" as the shell of the bubble at the nucleation phase-change point.... but how many degrees are we talking about?

PS: if going passive (without fan) you could also crosshatch/file the HS so the fins have "teeth" at the top... which will act as nucleation points

PPS/ i could be wrong about all this


----------



## technogiant

Quote:


> Originally Posted by *Butter Chicken*
> 
> make sure you use authentic Canadian Maple
> 
> 
> 
> 
> 
> 
> 
> 
> 
> wouldn't deliding the proc be safest method to attach the addition? but I guess after a delid resoldiering the IHS would be a little difficult...
> 
> as I have seen on delidded cpu's the chips is actually pretty small under there, so there is an air gap trapping heat in there unless the solder doesn't have a good seal and the fluid is allowed to enter the IHS.
> 
> my 2011 processor has this little hole in the top corner of the IHS and I've wondered if that it to allow the release of heat? other procs I seen without it.


Lol...well BC...as I'm Brit I'll remain patriotic and go with good old "Tate & Lyle" golden syrup....main reason being it doesn't recrystallize.

As regards deliding.....well I'm currently on a 2700k which I believe have a soldered on IHS....so don't really fancy the risk of deliding that.

Quote:


> Originally Posted by *RnRollie*
> 
> about the HS, leave as is, with the fan
> 
> The effort of creating the ideal HS with controlled nucleation is way to big/complex to pay off.
> 
> Ideally you would have to "coat" each fin of the HS unevenly, providing more nucleation spots near the bottom while having a smoother surface near the top ... or vice-versa
> 
> The more nucleation spots, the more bubbles can form, but the more they "stick" to those points untill they become large enough to have sufficient "buoyance" the rip themselves loose.
> Which is why each fin needs to be unevenly coated to facilitate this.
> 
> Imagine, for the sake of illustration, that each fin of the HS is 10 mm tall, and each mm differs one degree (bottom "hottest", top "coolest"), by controlling the nucleation points with variable "coating" you are actually optimising the HS for a certain temp "range". So, to work out the ideal coating, you need to find the ideal working range of the heat dissipation. Therefore you need to know how much heat you are going to produce... and when its all said and done you'll have to live with the possibility that the "tuned" dissipating range is smaller as the production range... unless you can produce an "oversized/overextended" dissipation range.
> While it is true that the "coolest" point would be the nucleation point, the duration of the bubbleforming (till it breaks free) could actually be counterproductive.
> In other words, in order to find the best HS nucleation range/setup, you'ld need to setup a lab with controlled variable conditions.... or do all the involved maths taking into account that a mathematical model does not always behave as it should in real life
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Oh, and you'ld also have the shorten each 2nd fin to half (or 3/4 or 1/4) the height of the adjacent fin. To avoid bubbles being "trapped" for too long.
> 
> My suggestion is to use the HS with the squirrel fan to move (lotsa) liquid as the easier solution to start off with. Its range will be wider but less efficient.
> Yes, it means that it will cool the CPU with liquid which is substantially "hotter" as the shell of the bubble at the nucleation phase-change point.... but how many degrees are we talking about?
> 
> PS: if going passive (without fan) you could also crosshatch/file the HS so the fins have "teeth" at the top... which will act as nucleation points
> 
> PPS/ i could be wrong about all this


Hi Rollie....yeah I've moved away from the idea of the coating.....I figure that if an uncoated IHS is sufficient to cool a server cpu then the area provided by the copper HS will be more than adequate.

I am however in the process of removing half of the fins...every other one....and while as you say its far too complex to make any calculations on this I just feel from subjective comparison that this will be far better than having the fins as tightly packed as they were in respect of trapping the bubbles.

Even with half the fins removed on rough calculation the HS has about 30X the area of the IHS.

I may try coating the exposed underside of the HS just as an experiment....if I notice far more bubbles coming from that area then it may be worth having a rethink on the coating....but for now I'm going to try just the partially de-finned HS passively without the fan.


----------



## technogiant

Well I'm stoked







just transferred my gas/liquid from the one pressure bottle to the other....using nothing but the pressure differential caused by temperature difference......nice little proof of concept that I'll be able to recover the fluid from the chamber basin back into the pressure bottle.

I just put the propane cylinder that I had previously emptied into the freezer...had it connected to a full butane cylinder at ambient temp, turned the butane cylinder upside down so that the liquid phase covers the valve opening, and open the valves. The higher pressure in the ambient cylinder forces the liquid phase from the upturned cylinder into the cold cylinder, the pressure then builds in the cold cylinder but because it is cold and at pressure the gas liquifies so restoring the pressure differential to allow more liquid to be pushed through.

The cylinders have the same volume so there was no worry of overfilling.....also I didn't want to transfer it all across just 18 liters of liquid butane.....so I weighed it as I was transferring it.....works out to 10.8kg with the density of butane liquid being 0.6g/cm^3

On a safety note I purged out the connecting pipe with butane before I connected the cylinders so it shouldn't have transferred any air into the cylinder.
I'm also going to purge off an amount of vapor from the refilled cylinder once it has returned to ambient....that will again purge off any air that may have somehow got in (it's less dense than butane so will sit at the top of the vapor space and so be purged off first when you open the valve)....just belt and braces really as I'm sure none did.


----------



## technogiant

Things progressing along nicely.....I've finished messing with the cpu heat sink.....I decided against trying a coating on it....firstly because I was concerned that if I couldn't get it thin enough it may actually hinder heat transfer.

Secondly because I've been thinking out where the cooling bottle necks are in this type passive boil off system......the limiting factor is that at heat densities above 6 to 10 watts/cm^2 the gas bubbles generated insulate the component.....this limit is present regardless of the efficiency of the coating.

So there's no point having a coating that can pass 10 gazillion watts/cm^2/deg C as you are still limited by the 6-10 watts/cm^2 boil off limit.

This is fine for Novec cooled servers as their heat density is sufficient to be cooled by the IHS alone so the special coating reduces the temp delta between the silicon and the liquid.

But I have to use a HS as the heat density of an overclocked cpu is greater than the boil off limit.....so having accepted that this extra layer is essential and that heat distribution in the copper block will be very efficient then the larger surface area of the HS not only reduces the heat density but also reduces the requirement for the surface to be so efficient as the special novec coating as you have more of it.....so although they state their coating produces a 15x heat transfer improvement, I have 30x the area through which to transfer heat (even though I've removed every other fin to increase the fin gap so bubbles don't get retained there)

A problem with using a HS in submersion systems though is TIM wash out, most TIM's are based on silicone grease which either dissolves in the submersion liquid or is just mechanically washed out.

I toyed with the idea of liquid metals but most contain Gallium which my damage my aluminium case.

So for the moment I've gone for a home made TIM that I've been testing......a mixture of syrup and alumina powder.

I've been testing it out for the last month and it has been giving better results by about 5 deg C compared to arctic silver 5.
Also daily blitzing with Intel burn test and prime 95 have not reduced its efficiency and it did not appear dried out when I disassembled yesterday.

I think the reason its better than arctic silver 5 is that the carrier (syrup) has a thermal conductivity 6X greater than silicone grease which is the carrier for most commercial TIM's

But the features that make it useful to me are that it will not chemically dissolve in the submersion liquid and at low temps it becomes super viscous almost solid so will not mechanically wash away easily.

It is of course a test and an unknown....pretty much like the whole of this project....but having thought it up I want to trial it....and I'll have to use it when I change my graphics cards anyway, my current gpu HS appears stuck on with thermal epoxy.....but when I upgrade obviously indigo extreme isn't an option for that....so it will have to be syrup/alumina...so this will be a good test while I'm waiting on 20nm gpu's to come out ( also determined to squeeze 1GHz or greater out of my gtx 460's...lol)

I may at some stage use Indigo extreme liquid metal as this doesn't contain Gallium.....I was concerned that I wouldn't be able to test it once I'd burned it in but found yesterday when I installed my HS that I can still run the pc even with just the HS being passive and partially de-fined....so it would be possible to check that the indigo extreme had actually "flowed" properly as I understand that it sometimes doesn't go to plan.

So today I will be putting my mobo in the chamber testing then sealing the lid on.

After that not much further to go, insulation of the chamber, assembling the purging system, sealing the cables externally and I'll be ready to go.


----------



## mindblowingj

So exiting to see things fall into place, cant wait to see some results, when are you uploading some pics ? ^^


----------



## technogiant

Hi MB, yeah I can't wait to get this thing running now......today I put the mobo in tested it and sealed the chamber lid on....I've kind of given up on taking pictures....as with all my builds it's a mass and mess of cables and pipes......but I have put a web cam in the chamber which will hopefully give me some footage of the the boiling off and filling/emptying process in action which I'll be able to share.

Tomorrow I'll be overlaying the lid joints with 90 degree aluminium angle to ensure they're completely sealed and starting on the insulation.....I've still got to stick the secondary chamber over the cables where they exit the main chamber and join to the extenders,...I'm still undecided about what fluid to use in there to prevent air getting sucked in....I've got several ideas floating around....but each have pro's and con's....just can't decide atm but sure I'll decide come the time to do it.


----------



## RnRollie

have you seen this?
http://www.versarien.com/technology/


----------



## Chickenman

Quote:


> Originally Posted by *RnRollie*
> 
> have you seen this?
> http://www.versarien.com/technology/


I asked them some questions on their facebook page and as advised have sent an email to the sales team. Hoping that there is something of worth, something new









Not really holding my breath for a game changer though.


----------



## technogiant

Interesting.....not sure I can think of a particularly viable usage scenario though?.....unless I'm missing something...which is more than possible.


----------



## technogiant

So the lid is now completely sealed on with the aluminium angle sealed over all the joints.....I've bought my insulation board and cut that to size.....I've got commitments for the rest of this week but hopefully by the latter part of next week I'll be testing.


----------



## Chickenman

Quote:


> Originally Posted by *technogiant*
> 
> Interesting.....not sure I can think of a particularly viable usage scenario though?.....unless I'm missing something...which is more than possible.


Quote:


> Originally Posted by *Versarien CEO*
> Thanks for the enquiry, most of our work has been in high end power electronics in things like F1 and Wind turbines. However I have always been an enthusiast and we started using the material in my machines for CAD and rendering. No high pressure pump as we have worked hard to optimise the structure to give a good balance between porosity and thermal transfer, and the process gives very repeatable reliable consistency in terms of the structure. It is in fact this feature that gives us a clear advantage over other processes.


----------



## technogiant

"No high pressure pump as we have worked hard to optimise the structure to give a good balance between porosity and thermal transfer"

That does make it more interesting...I was thinking it would be very restrictive to flow.....so that does open up some interesting avenues.


----------



## mindblowingj

internal base of LN2 pot ^^


----------



## technogiant

Quote:


> Originally Posted by *mindblowingj*
> 
> internal base of LN2 pot ^^


humm don't know ....would it....or would the holes just fill up with gas and effectively insulate the component from the LN2.

Think if fluid was actively pumped "through" the material it would be of use (at least now that they have confirmed its not restrictive to flow)....but for passive boil off like with LN2 and my project I think it would end up insulating.

Might be interesting to use inside the head of phase change unit?...having the fluid injected on one side of the block of material and sucked away on the other side?


----------



## RnRollie

Quote:


> Originally Posted by *technogiant*
> 
> humm don't know ....would it....or would the holes just fill up with gas and effectively insulate the component from the LN2.
> 
> Think if fluid was actively pumped "through" the material it would be of use (at least now that they have confirmed its not restrictive to flow)....but for passive boil off like with LN2 and my project I think it would end up insulating.
> 
> Might be interesting to use inside the head of phase change unit?...having the fluid injected on one side of the block of material and sucked away on the other side?


it's "perforated" copper.... if you would make a rod out of it, it could replace a heatpipe i recon









when is the big bang due?


----------



## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> it's "perforated" copper.... if you would make a rod out of it, it could replace a heatpipe i recon


Perhaps I'm being thick...but I just cant see how?








Quote:


> Originally Posted by *RnRollie*
> 
> when is the big bang due?


Don't even joke...lol....well I'm having a little difficulty cramming all the cables into the external "slush box" atm....but I'm off work for a while now so will be able to have a proper go at it....may have to send off for some more power extenders which would cause a little delay but hopefully not....if all goes well then I'll be purging the system and leak testing by Thursday and hopefully running and testing by Saturday....If I have to send off for more stuff then we'll be looking at next week....so fingers crossed.


----------



## technogiant

Okay...I've finally got this thing assembled to a point where I can start doing some stuff with it.....I've insulated it the best I can, I've submerged the cable connections externally in oil so they can't draw air in and I've purged the system with Nitrogen gas to remove the majority of the oxygen.

I'm currently doing a test run with just the air con unit and internal fans going...no pc or load.....I'm really surprised at how long it is taking to pull the temperature down.....I was starting to think there was something wrong with the air con unit or my insulation job was rubbish.

With my previous build which was just filled with air and the inner box was the insulation board then it would pull the temp down to -20c in a matter of dunno perhaps 5 mins and -30c in about 10 mins....somewhere around that area.

I've been running the new chamber for over an hour now and just hitting -11c.... :-/

The temp is still going down slowly but surely......I think it is the heat capacity of the alu chamber.....it weighs over 62kilos so has the same heat capacity as about 3 imperial gallons of water.......that's gota take some cooling.....think I'm just used to instant temp drops with my previous system....still going down....-13c now.

The reason I'm doing this with just the Nitrogen in there is to leak test it. The chamber was sealed at ambient of +20c and I completely evacuated the purge sac.

Leaving it run at low temp in this sealed state will drop the internal pressure by between 2 and 3 psi so if there are any leaks air will be drawn into the chamber.

After several hours I'll turn off the cooling and allow it to return to ambient temps as the temps are returning to ambient I'll open the purge sac line....if air has been drawn into the chamber then as temps return to normal the purge sac will be expanded as compared to its previous evacuated state.

It's not a particularly accurate method but it should be good enough to show me if there are any substantial leaks.

I'll do the same again tomorrow when I have purged the Nitrogen out with butane.......the butane will produce an even lower pressure...perhaps as much as -10 psi .......so that will give an even more rigorous test.....if all is good with that then I'll be able to load the chamber with liquid butane and try booting up
 








Finally got down to -22c without load after several hours of no load running......doesn't seem right to me...just took too long to get down there and is some 8c higher than the low I could get before.....although I am monitoring the temp on the outside of the alu chamber rather than the air/gas temp inside as I was before....guess I won't really know till I try some loaded trials.

I'll monitor how long it takes to return to ambient.....if the problem is my insulation job isn't good enough then I guess it will return to ambient quite quickly....other than that may be an air con unit problem...or just the additional heat capacity...not sure.


----------



## technogiant

Well it's early morning here in UK now, and the chamber has been standing overnight....I shut the system down about 10 hours ago at -22c.....its still showing an outside chamber wall temp of -1.9c....so it seems to be holding the temp fairly well...so don't think there is a major problem with the insulation although I'm going to improve on that in time.

The other very positive point is that there is still a partial vacuum in the chamber....chamber temp as stated -1.9c and ambient is now +13c....when I opened the shut off valve to the purge sac which I had already expelled as much of the gas out of as I could it actually sucked it even flatter.

So it seems that the chamber doesn't have any leaks as that vacuum would I think have dissipated over night if there was any substantial ingress of air.

Today is where I really get down and dirty with the first butane tests.....I'm going to partially re-purge with Nitrogen first and then purge through with butane.

Then I'll do another no load run with just fans and ac unit going....may even try and use the chamber interior lights and web cam.....so here's hoping the theories work in practice.


----------



## technogiant

Well that's got to class as about the scariest thing I've done in a long while.

Purged out the chamber with butane...then it was time to start the fans.....I was hiding behind a wall at the end of a long extension cable.....I switched the switch...and guess what....no singularity formation....no big bang....thank goodness.....theory seems to be turning into practice.

Feeling emboldened by this I started all the fans the lights and the internal web cam......still no flash or bang.....so it was time to crank up the air con unit.....again no apparent drama....so I'm watching the web cam feed from inside the chamber....is this going to work or not....the temperature starts dropping and there appears to be a haze at the bottom of the evap where I've left a channel in the shrouding for the liquid condensate to run back into the basin.

I'm watching this like a hawk.....the haze starts to thicken and turn into drops of liquid butane dripping down onto my mobo.....the drips turn into an intermittently spouting jet of liquid butane as the channel in the shrouding alternates between letting gas get sucked through and then letting the butane run out when it has gathered enough head. It's impossible for me to tell how much liquid is being generated in terms of ml/s...but what I do know is it doesn't need much.... 4ml/s equates to 1kw of cooling.

I let it run until the chamber got down to -4c at least as monitored on the outside of the chamber wall...I suspect the internal gas temp to be much lower....and that bit of the mobo where the liquid butane was landing must have been real cold.....but sadly rain then stopped play....atm I'm running all this of an external extension lead so had to shut down when the wet stuff stared falling.


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## RnRollie

looks like it's time to reposition a few spy sattelites...


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## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> looks like it's time to reposition a few spy sattelites...


Oh don't Rollie......I'm petrified enough as it is doing this.

So the latest news.....restarted the system with just gas in it and booted up the computer......again thankfully ok.......went into the bios hardware monitoring and saw the chipset was at -29c...so sort of confirms that it was as I thought...internally things are a lot colder than the external temp sensor is indicating...that's the sort of temp I was getting with my previous build and this pc setup.

So decided to go for it and introduce the liquid butane phase.......real scary stuff.....I just let it in a bit at a time....constantly checking that the chamber pressure was still negative......real scary watching that stuff start to lap over the sides of my mobo tray and progressively upward....over the chipset heat sink and I finally stopped transferring just as it was lapping onto the surface of the cpu heat sink.....I was just too scared to go any further at that time in case I have difficulties returning the liquid to the pressure bottle.

The liquid is like a boiling cauldron as it is permanently right at its boiling point which is being determined by the balance of temperature and pressure (negative pressure actually) It's so counter intuitive to see it boiling like that while there is a negative pressure in the chamber, you associate boiling liquid with high pressure production ....weird stuff .

I booted to windows just at default cpu settings (2700k)......I don' think temps are representative of normal use as yet as I didn't have the liquid right over the cpu heat sink it was just lapping at the edges.

Did a very quick Intel burn test on standard which gave +7c on one core and zero on the rest......but the purpose of this was really to see if there was any pressure build up in the chamber while under load......but it was still negative....so good there.

I'm now trying the fluid return procedure......so I have the cylinder in the freezer with the valve wide open.....I've turned the ac unit off so as the chamber warms and the bottle cools the liquid should be forced in the opposite direction back into the bottle....still monitoring with the web cam...here's hoping.


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## technogiant

Seems to be working.....the Stainless steel hose that links the chamber to the bottle in the freezer is starting to get frosted up on the chamber end.....indicating that cold liquid is starting to move out of the chamber back into the bottle.......I'll have to lag that at some stage but for now its given a good indication its working.


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## technogiant

Wow that happened all of a sudden.....chamber temp got to about -10c.....not sure what the freezer temp was...but the chamber emptied all of a sudden.

I'm not much good at this sort of thing but I've got a little bit of video uploaded to youtube......it just shows the liquid bubbling away while it is being transfered back to the bottle.


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## ZytheEKS

ermergerblerdurhurferder!!!

It's working! You mad genius!

Let us know when you start trying to push an overclock on it.


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## technogiant

I have no idea what that means...but thanks Zythe.

Yeah I must admit I'm really pleased.....I mean without blowing my own trumpet....I think this is a real first....I've certainly not seen anything like this before....and the fact that I've thought it all out from scratch and it worked first time....I'm chuffed.









Still not going to get complacent....seeing that 10 -20 liters of liquid butane boiling away didn't just cool my pc....it also left me quite cold and fearful of the consequences of a mistake.

I'm just using this for proof of concept atm....if it works out and gives good results I may swap the butane for something else...non flammable....I've been considering HFC 227ea commonly known as FM-200 bp of -16c often used in fire extinguishers....trouble is it cost £360 for a 13kg cylinder an d I need two of them...so have to be sure this is a worthwhile and sustainable build before I buy that.


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## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I have no idea what that means...but thanks Zythe.
> 
> Yeah I must admit I'm really pleased.....I mean without blowing my own trumpet....I think this is a real first....I've certainly not seen anything like this before....and the fact that I've thought it all out from scratch and it worked first time....I'm chuffed.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Still not going to get complacent....seeing that 10 -20 liters of liquid butane boiling away didn't just cool my pc....it also left me quite cold and fearful of the consequences of a mistake.
> 
> I'm just using this for proof of concept atm....if it works out and gives good results I may swap the butane for something else...non flammable....I've been considering HFC 227ea commonly known as FM-200 bp of -16c often used in fire extinguishers....trouble is it cost £360 for a 13kg cylinder an d I need two of them...so have to be sure this is a worthwhile and sustainable build before I buy that.


They use that expensive of a chemical for spraying on fires? No wonder the government has no money.....


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## technogiant

Okay so I've been brave today and filled the chamber as far as I could tell to the top of the gpu heat sinks or there about.

I've done some benchmarks and shut the system down again and recovered the liquid to the pressure bottle.....all went well again.






Just some video of the full chamber bubbling away again...enjoy I'll be posting up some tests/temps in a few minutes.


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## technogiant

So here they are and sadly not all I was hoping for.

First up is wprime155 1032m at 5.5GHz and 1.51vcore. 8 threads hyperthreading on.

I wanted to do this as I recall my max temp with my previous chill box was at these setting on the same hardware was +52c

http://imageshack.us/photo/my-images/27/h8of.jpg/

Uploaded with ImageShack.us

So you can see that the min max are 30/36c

not bad for a 5.5GHz overclock.....but I must admit I was hoping to be completely sub zero.....but it's almost almost a 20c improvment.

Next up the beast Intel burn test

First did it at default clocks 3.6GHz on very high setting

http://imageshack.us/photo/my-images/811/3v6f.jpg/

Uploaded with ImageShack.us

Just let it roll for about 2 mins and the temps reached 0/1/7/10c

Next up overclock of 5.4GHz and 1.51vcore Intel burn test on standard.

http://imageshack.us/photo/my-images/607/xk97.jpg/

Uploaded with ImageShack.us

max temps of 39/46/48/50c........previous results at this setting were min/max 54/69c

next up IBT on maximum settings 5.4GHz 1.51vcore

http://imageshack.us/photo/my-images/35/o4qy.jpg/

Uploaded with ImageShack.us

I only let it run for about 5 mins temps of 43/50/52/55c......previous results were high 70's to low 80's

I didn't try it at 5.5GHz as that used to crash my system previously......but it may be the lower temps will make it stable.

Also haven't tried booting to 5.6Ghz.....could never do that with previous build..may be worth a go with this system.

Also did a quick furmark test with the gpus.....2xGTX460 2gb versions by palit.....reference clock is 675mhz got these at 920mhz 1.137volts

they used to get to about 50c at those setting then crash......I don't have screenies of this but they went to +12c on gpu1 and +5c gpu 2.

So that's not a bad improvement.....I wanted to try these as the solid metal heat sink appears stuck on there with thermal epoxy.

It may be I've messed the tim up on my cpu....used my home brew of syrup/alumina powder.....but fear I may have put too much on.









Still not bad for first run at this.


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## ZytheEKS

... Something isn't right there. It sounds like maybe the A/C unit isn't able to condense the butane as fast as it boils off.

I don't see why it would be able to go beyond 0c if the phase change function was working properly.


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## technogiant

I think it's probably the cpu tim....think I put too much on there.....I'll go with indigo extreme next time.

Don't think its a boil off problem or a re-condensing problem....I mean there is plenty of liquid in there so its not starved of liquid even if it was not re-condensing properly......If it wasn't re-condensing then there would be a pressure build up.....I've tested for this.....when under load I've opened the line to the purge sac and it has sucked further butane in showing it is still under negative pressure......so the boiling point of the butane will still be below -1c which is its value at standard pressure.....don't have values or means of measuring the exact pressure but there is considerable neg pressure in there so the butanes BP will be considerably lower than -1c.

Think its the tim...I'll listen to Rollie next time and and lap the thing.









Also when I'm introducing the liquid to the chamber the liquid is warmer than allowable for the pressure in there so it boils off to an extent....you can see the evap in action at that point.....condensate is cascading off it like a monsoon....it only takes 4ml/s to cool 1kw so don't think this is the problem.


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## RnRollie

congrats, i never doubted you for one second









do you have temp probes sitting in the LiB, preferably away from any boil-off spots?
Would be nice to check if you've got circulation dead spots, resulting in the LiB being "hotter" as anticipated near the CPU.

Might need some "moar" LiB, so the MB is submerged deeper... could do the brick-in-toilettank trick to raise the liquid level








or might need some vanes/baffles to force circulation.

And, yes, of course... lapping CPU & HS


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## technogiant

I'm also wondering if I'm hitting internal cooling limits within the cpu due to heat density......don''t know if this is the case.....someone may well have info that will blow this argument out of the water.....but cpu's aren't as easily cooled that gpu's.

Gpu's have a larger silicon area and lesser heat density compared to cpu's especially when you consider that about 1/2 of the cpu silicon area is integrated graphics.....is it possible that once running at full load like on Intel burn test at a high overclock that it is the heat density within the cpu that becomes the limiting factor and regardless of your cooling systems you won't improve temps?

I'd be interested to know what silicon temps really powerful cascade systems or LN2 systems achieve running IBT on max at clocks the same as I have.....anyone got that info?


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## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> congrats, i never doubted you for one second
> 
> 
> 
> 
> 
> 
> 
> 
> 
> do you have temp probes sitting in the LiB, preferably away from any boil-off spots?
> Would be nice to check if you've got circulation dead spots, resulting in the LiB being "hotter" as anticipated near the CPU.
> 
> Might need some "moar" LiB, so the MB is submerged deeper... could do the brick-in-toilettank trick to raise the liquid level
> 
> 
> 
> 
> 
> 
> 
> 
> or might need some vanes/baffles to force circulation.
> 
> And, yes, of course... lapping CPU & HS


Hi Rollie and thanks.....and thanks for keeping me on my toes with my design ideas.

I don't have a probe within the chamber at all....the nearest I have is the hardware monitoring in the bios...says system temps are -29c.

In theory there should not be any hot spots.....the liquid is right on the cusp at liquid/vapor equilibrium for the pressure in the chamber so any hotter area should vaporize....so the cooling model is not based on circulation of liquid just transition between liquid and vapor.

The chamber has plenty of liquid in there to cover the cpu so no need for the toilet/brick trick .

Think the "problem" is either my TIM







or one of internal heat density


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## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> I'm also wondering if I'm hitting internal cooling limits within the cpu due to heat density......don''t know if this is the case.....someone may well have info that will blow this argument out of the water.....but cpu's aren't as easily cooled that gpu's.
> 
> Gpu's have a larger silicon area and lesser heat density compared to cpu's especially when you consider that about 1/2 of the cpu silicon area is integrated graphics.....is it possible that once running at full load like on Intel burn test at a high overclock that it is the heat density within the cpu that becomes the limiting factor and regardless of your cooling systems you won't improve temps?
> 
> I'd be interested to know what silicon temps really powerful cascade systems or LN2 systems achieve running IBT on max at clocks the same as I have.....anyone got that info?


Short of using cascade TECs to spread the CPU heat it might be tricky to deal with the heat density of the CPU, if that is indeed the problem. Hopefully it will just be a TIM issue.


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## technogiant

Quote:


> Originally Posted by *ZytheEKS*
> 
> Short of using cascade TECs to spread the CPU heat it might be tricky to deal with the heat density of the CPU, if that is indeed the problem. Hopefully it will just be a TIM issue.


I've been talking with a guy on another forum who runs a chilled water loop at between -20c to -30c.....by comparison he was getting very similar temperatures at the silicon level on the same processor and almost identical settings.

I'm fast forming the conclusion that the silicon temp is due to internal cpu heat transfer limitations rather than the effectiveness of the cooling system...I think that beyond a certain heat production that the heat transfer within the cpu becomes the limiting factor and no matter how powerful the cooling the final silicon temp is going to be dictated by the silicon itself irrespective of the cooling system.

I think its telling that my results were almost the same for the same hardware and similar settings to the guy with the chilled water loop even though are cooling systems are completely different.

But having said that I will attempt improvement...I'll give indigo extreme a shot as a tim and I've thought of a way to coat the HS with powder as I originally wanted to do...just not sure when I'll be opening the box to do that.


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## RnRollie

welll... its likely that silicon limitations play a role... shoot of a mail to intel and ask about it
Most likely they'll reply that their regular consumer batches are not specced to run at subzero; they'll probably tell you to use one of their special Xeon processors


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## technogiant

Quote:


> Originally Posted by *RnRollie*
> 
> welll... its likely that silicon limitations play a role... shoot of a mail to intel and ask about it
> Most likely they'll reply that their regular consumer batches are not specced to run at subzero; they'll probably tell you to use one of their special Xeon processors


I think it insane I'm getting an 80c temp delta when I have the thing submerged in liquid gas.

I've been doing some calculations on thermal conductivities and temperature deltas and think I've come up with the answer.....

I think it is due to limitations in the cpu.......not the silicon itself which has a high thermal conductivity of 149 w/m/c but the solder layer......the lower temp melting point solders which they must use, from the info I've found have conductivities of between 20 - 50 w/m/c

Sandybridge total die area is 216mm^2......only about half of that is dedicated to cpu so 108mm^2

Now I'm not sure of the power usage of a 2700k at 5.5ghz and 1.51 vcore core temp says about 140watts but most people say 200-250watts for a clocked cpu so lets be conservative and say 200watts....and lets go down the middle with the solder and say it has a conductivity of 35w/m/c and a thickness of 1mm.

Q(heat flux watts) = K (thermal conductivity w/m/c) x A(contact area M^2) x (T2-T1 temp delta) / T(thickness M)

200=35 x 0.000108x(T2-T1) / 0.001

So resolving this for delta T you get a temp delta of 52.9 deg C just across the solder interface.

Like I thought.....it's the high heat density interfacing with the solder causing such a large delta...not much can be done about that...just try and reduce the deltas at the other interfaces but you are saddled with a +50c delta you can do nothing about.


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## ivanlabrie

This is absolutely insane








Mad props, and will keep an eye on your progress.


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## technogiant

Quote:


> Originally Posted by *ivanlabrie*
> 
> This is absolutely insane
> 
> 
> 
> 
> 
> 
> 
> 
> Mad props, and will keep an eye on your progress.


Hi Ivan, yes insane would be a good description..but I've knocked the project on the head now....don't misunderstand....it worked just as I hoped it would from start to finish and the method to submerge in liquified refrigerant gas was good......but I was using liquified butane as the submersion liquid.....potentially catastrophic.....I think I was so focused on making this work I put that to the back of my mind......but the reality of standing next to a chamber with 18 liters of liquid butane and 135 liters of butane vapor inside it while your running electrical components within it is very very scary.

I was considering using a different type of refrigerant but the expense of this wouldn't be justified....ultimately it was more of an experiment, a working through of my thoughts than a system that could be used 24/7....and that has been done.

It could be evolved into a 24/7 system but I don't have the funds, facilities or engineering expertise to do so.....so I will leave it there...as a proven proof of concept build for what could be with further development an extremely effective type of system.


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## ivanlabrie

I agree, it was a ticking time bomb man









I admire your courage and expertise though, it's amazing that you came up with something like this and eventually got it to work







+rep


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## technogiant

Quote:


> Originally Posted by *ivanlabrie*
> 
> ....it's amazing that you came up with something like this and eventually got it to work
> 
> 
> 
> 
> 
> 
> 
> +rep


All power to the inventors of the world.....the unseen army of little men working in their sheds....lol


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## CallsignVega

Good read. Sorry that the temp delta turned out so high on such a design. Does anyone know what the temperature delta is on Ln2 runs? You would think they would be similar if there is a limitation within the CPU and not with the cooling itself as speculated.


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## ZytheEKS

Quote:


> Originally Posted by *CallsignVega*
> 
> Good read. Sorry that the temp delta turned out so high on such a design. Does anyone know what the temperature delta is on Ln2 runs? You would think they would be similar if there is a limitation within the CPU and not with the cooling itself as speculated.


Liquid Nitrogen boils at 77Kelvin, about -195 Celsius so it boils about 100celcius lower than his build. Since his chamber is under negative pressure his butane boils at a higher temp.

Techno, you should consider trying to do a direct die type application and see what kind of numbers you get. Maybe the heatsink is the weak link. If it was direct die the CPU boils the butane, and that boils off. If you use a heatsink, the cpu heats the heatsink, and that boils the butane. Since you are relying solely on evaporation you might notice better results with direct die. It's worth a shot, since you already plan on taking the heatsink off to reseat it.


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## technogiant

I would like to see what kind of silicon temps an LN2 system would produce running IBT on max settings at 5.5Ghz.....if the limitation is internal then they should like wise have a large heat delta...but LN2 users don't generally do that sort of thing they just go for max OC frequency and run a non intensive benchmark. But it would be interesting as it would test out the internal limitation theory.

Another possibility is the TIM ...I've disassembled and found it was washing away despite my plans that it shouldn't.

Zythe I'm not actually pursuing the project further atm as it's too risky......but to use direct cooling of the die wouldn't work as the heat density of the surface area is too great...thats why you have to use a heat sink....above 6-10 watts/cm^2 the bubbles generated start to insulate the component....the only way to get direct die cooling would be to have a forced flow over the die surface.....perhaps by means of a pump to actively drive off the bubbles.


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## ZytheEKS

Quote:


> Originally Posted by *technogiant*
> 
> *snip*
> 
> Zythe I'm not actually pursuing the project further atm as it's too risky......but to use direct cooling of the die wouldn't work as the heat density of the surface area is too great...thats why you have to use a heat sink....above 6-10 watts/cm^2 the bubbles generated start to insulate the component....the only way to get direct die cooling would be to have a forced flow over the die surface.....perhaps by means of a pump to actively drive off the bubbles.


It's unfortunate to hear you aren't going to be continuing this, or at least not in the near future.

If heat density is this prevalent of an issue issue, perhaps a you could decrease the heat density by using a peliter. Since they actively move heat, a coldplate and a nice big 62mm peliter, or perhaps several cascaded smaller peltiers would increase the surface area, while allowing active thermal transfer, simultaneously keeping the reliance on evaporation. I wonder if they would still operate properly at such low temperatures though.


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## technogiant

Yes I'd be really interested to know if heat density is the issue here.....if it is then I think there would be little that could be done....very high overclocks at high load would have a large inherent heat delta.....but this may just have been an issue with the TIM...just don't know...but I am aware of another extreme chilled water cooled build that has similar large temps deltas on the cpu but not the gpus (which have lower heat densities) so there may be a nugget of truth in this discussion even if it is not the whole story.


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## Jetskyer

Very informative read, enjoyed reading this thread from start to finish!
Too bad you can't make a running 24/7 system out of it but looking at the (relatively) high load temps I can totally understand that it doesn't justify the risk or cost.

About the heat transfer limitations of the CPU I think you have very much overestimated the thickness of the solder. Although if the IHS isn't pressurized when soldered the capillarity of the solder might try to raise the IHS, making the 'gap' close to or even greater than 1 mm.
You could possibly ask vaulgar (from the delidded thread) if he could run a prime95 run on a CPU that's pulling around 200 watts on LN2. I would be very much interested in his findings, and I doubt I'm alone in this


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## technogiant

Hi Jetskyer,....that's some dedication right there reading the entire thread...lol

I think part of the problem with the large temp delta was the cpu TIM that I used......on disassembling it I found that the outer regions of it had gone quite liquidy so that didn't work as I hoped....a better idea would be to use a non gallium metal alloy that would solid at the temps required.

But I also noted that even on the gpu's which had solid heatsinks attached with thermal epoxy that although the temps were a big improvement on my air cooled chamber....about 40c lower the temp delta was still quite large about +10c while surrounded by -30c liquid butane. I really was hoping for better temp deltas than that and can only think that even with the larger gpu die area and so lesser heat densities that some fundamental limits are being reached either within the silicon or its interface when you put so much power through them.

So in all as you said the risk/cost appears not to make it viable if these deltas are fixed.

I have toyed with the idea of using the system at atmospheric pressures as was my original intention as air sucking in would not be such a concern but I've been banned by the wife from anymore such risky projects....lol.


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## Jetskyer

Heh yea, I just had this tap open at all times. When I had to wait for something I just went at it and read another page or two. Finished the last posts here in Norway since it's a very efficient thread (data-wise. only got 35MB's a day here on the cellular network)

But you're right, 40 degree delta for the gpu's is quite high. Although one might expect the thermal adhesive isn't designed to work at temperatures around freezing point but that's just speculation from my side. Other than that I recon the temperature sensors are at the far end of the silicon (the PCB-side) which isn't heatsinked. I would say that the distance through the silicon, the thermal paste and into the heatsink all adds up to too much resistance.
Another thing that crosses my mind with the gpu's is that it's heatsink probably is aluminum and of course optimized for air. The distance the heat has to travel through it most likely is so much that the tips of the aluminum are near the butane temparature, whilst the base is closer to -10 to 0 degrees.
This of course can be disproved by a simple calculation but since it's the holiday I'm not going to do that









I wonder a little what would happen with a delidded ivy but that's not really worth the trouble.
It's cool you've come this far though!


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## Qitix Ouiren

Im a little late to the party but i wanted to show a video I saw on youtube that show case a similar build using a different chemical.


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## technogiant

Yeah that works on just the same principle except that the boiling point of that liquid is 34c at standard pressure, and they use ambient air to cool and recondense the vapour......and a very big plus point its not flamable.


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## technogiant

Hi again guys.....I've sort of been taking some time out of dreaming up cooling solutions....this last attempt although it worked was somewhat abortive due to the risks and tbh having submerged my whole pc in liquid butane anything else I was able to think up all seemed a little lack lustre.

But I haven't been able to shut down completely.....its an addiction and I keep mulling over possibilities.

One thing for sure is the next project has to be safe (or the wife will divorce me).

As before I want to use a stripped down ac unit as the cooling source instead of custom built phase change units and I want phase change to form a major part of the component cooling.

I am going to abandon the full submersion aspect of the previous design as suitable submersion fluids capable of phase change are either too expensive, not available to the public or flammable.

My most recent idea and the one I'm seriously considering is somewhat hard to describe, it would be in some ways similar to my previous project being a large sealed vapour chamber using water/glycol mix as the working fluid, the evap of the ac unit would be inside the unit cooling the vapour.

The pc components would be housed in a separate sealed chamber and the liquid phase from the vapour chamber would be pumped to that chamber to cool both the chamber and components.

So it would be very similar to having a separate reservoir containing the ac unit evap and cooling fluid except that this reservoir would be a vapour chamber at low pressure, so that the fluid being pumped around the loop would not only cool by conduction but would also phase change at the hot components increasing the cooling efficiency.

The one problem that I envisage would be that the vaporisation process would liberate pure water vapour free from the glycol antifreeze and so would re-condense as ice on the evap fins. This could be overcome by having the return flow from the cooling loop running over the evap fins so that the water/glycol mix would melt the ice which had formed.

It has the potential to deliver powerful cooling as it combines both standard water loop conductive cooling and phase change, the vaporisation of water which absorbs about 10X the energy per cm^3 of liquid evaporated when compared to refrigerants.

So early days with this yet.....as ever...any thoughts guys?


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## mindblowingj

YAYYYY !!!! New project always is great, I'm looking forward to reading you again


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