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Old 04-05-2013, 08:36 AM   #41
technogiant
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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.

Additional Comment:

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/stainles...ize-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.....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.c...s_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-chl...FRTMtAodzBsAfQ

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.

Last edited by technogiant; 04-05-2013 at 11:09 AM. Reason: Automerged Doublepost
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Old 04-13-2013, 12:13 PM   #42
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You can just use any dual valve/port recovery bottle.. there's a 12L on ebay uk for 76.00. They normally have an extra ftg for float switch or sensor. Maybe you can use that for quicker fill/drain. Here's a video where you can see what the dip tube looks like. Forward to 1:36 of vid. http://www.youtube.com/watch?v=I5MYqAGVy28

Nice find on the stainless tray!

How are things coming?
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Old 04-19-2013, 12:28 PM   #43
technogiant
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Yeah the recovery bottles are ideal for my purposes with the dip tube, I'd have to go with a larger 26 liter one though as I could be using up to 15 liters of liquid.

http://www.ebay.co.uk/itm/REFRIGERAN...9334%26ps%3D54

One problem I have though is connecting to the flexible stainless steel hose.

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

I want the 2m hose and the only one they do at that length has a 21.8 LH fitting....do you know of an adapter to connect that to the recovery bottle? Other than that I'd have to go with a standard butane bottle which fits it directly or a propane bottle which I know I can get an adapter for.

I've had a bit of a hiccup to start of with, that stainless steel basin arrived but the quoted size included a lip around the outer edge and didn't allow for the basin narrowing towards the base....so the mobo doesn't fit

Still I'm not going to fall at the first hurdle and I've order this instead

http://www.sealey.co.uk/PLPageBuilde...nly=&fulltext=

It's galvanized rather than stainless steel so doesn't look as nice, but never mind it will give safe leak-less containment of the fluid in the chamber.

I've also been unable to source the refrigerants I wanted and have no option now but to use what I have available to me.......trouble is those options are flammable.

I'm going to use isobutane as the liquifying component and propane as the background gas.

I know this may sound very dangerous but I have thoroughly researched this and I'm confident I can do this safely.

When initially loading the system I will firstly purge it with bottled nitrogen (oxygen free)....while it says oxygen free it actually contains from 3 - 5% oxygen.

I will then fill with propane as a background gas...you may ask why use propane and not just leave the nitrogen in there as intuitively it seems safer to leave an inert gas in there.

The problem is that it would be difficult to maintain oxygen levels below the lowest concentration that would support combustion.

http://en.wikipedia.org/wiki/Limitin..._concentration

If you look at the above footprint for methane you see that the lowest oxygen concentration to support combustion is about 12%. Now given that oxygen free Nitrogen contains up to 5% oxygen then that doesn't leave much room for error and oxygen ingress that will undoubtedly occur.

So the safest method is to just use the nitrogen to initially purge the system then fill with propane as combustion is also limited by the upper flammability concentration.

http://www.engineeringtoolbox.com/ex...its-d_423.html

From the above table you can see that the upper flammability limit of propane is 10.1% and that of isobutane is 8.4%, so the limit for a mix of the two will alter between those values depending on the ratio of the mix.

It will be much easier to ensure that the propane concentration is above 10% than it would be to ensure the oxygen content was between 5 and 12%. In fact I will be keeping the propane/isobutane concentration as close to 100% as I can...so there will be a big difference/safety margin between the 10% flammable limit and the 100% level I'll be aiming to maintain.

Regular purging with propane being fed in from the bottom of the system and emptied from the top will ensure the air content which is lighter will be preferentially removed from the system.

One thing I would have to be mindful of is that after a period when the system had been allowed to stand idle, due to the higher density of the propane it will pool at the bottom of the system and the air at the top, so it may be that as you progress from the bottom to the top of the chamber that the concentrations may be within the flammable range. I intend to overcome this at system start up firstly by purging the top layer out followed by using one of the fans at the bottom of the case (and so in the propane rich non flammable region of the chamber) to mix the chamber contents.

Once the fans are running the turbulence will mix the gas into a uniform concentration which cannot ignite.

The fans themselves are brush-less and all the cables and cable connections to them will be sealed so will not be an ignition source.

So I'm happy that combustion will not be a problem within the chamber.

The greater risk I believe would be from leakage out of the chamber. particularly as I will have a freezer next to the chamber which as it cycles on and off even when I'm not present would represent an ignition source.

I can combat this by firstly ensuring that the chamber is as leak free and sealed as possible.

I believe my idea to have the lid and cables sealed via fluid filled "U" shaped traps will be pretty much leak proof and so the only loss of flammable gas will be via diffusion through the chamber materials and seals themselves and will so be very minimal.

In any event I intend to have the area this is contained in ventilated 24/7 by fans at the bottom of the area, again because propane/isobutane are heavier than air.

That together with a gas detector alarm will ensure this will be safe.

Additional Comment:

Hey Drew, just had a thought about your thermosiphon idea. Was wondering if you think a standard pc water cooling radiator could withstand the vapor pressure of isobutane at ambient temps...what is that...about 3 bar?

Reason I was wondering is that I've just had a brill idea about a variation of this. Instead of having a boiling chamber and pipes leading to a condenser just mount the base of a radiator in direct contact with the cpu.....you'd have to solder a copper shim onto the rad base to allow for direct contact with the cpu heat spreader and to give enough height for clearance...so the base of the rad would in effect become the boiler and the water channels the heat pipes.

Could use pgs graphite sheet to spread the heat over the rad base.

It would be a bit like a combo of a vapor chamber with several heat pipes running from it.

I can see it would be a bit of a ***** to mount....could also be adapted for gpu cooling as well...and that would be even more difficult to mount....but not impossible.

All depends really on how much pressure standard pc rads can take?

Additional Comment:

********

Okay as you've probably guessed from my continual chopping and changing I've been very undecided as to which way to go with this build.

My ideal would be full submersion in liquified gas.....but due to the fact there was considerable danger in using large volumes of liquified gas not to mention the only ones I could source were flammable then I was going to have to build an out house to do this build in......it's become apparent that its not going to be worth the effort and inconvenience and frankly expense of doing all this.

All of the other methods involving liquid gas have considerable build problems......so as with most things in life I'm having to strike a compromise. I want to do something that can more safely be done in the house.

I'm going to have to sacrifice the the liquified gas / phase change aspect of this.

I'm going for a toned down version that will use submersion / liquid cooling but without the phase change aspect as the liquid has a +69c boiling point.

I will simply submerge the mobo and pump the liquid over the top of the evap to cool it and allow it to run down the fins and back down into the sump.

I won't be pumping the liquid through water blocks but will simply attach large sheets of panasonic pgs graphite to the cpu/gpu heat spreaders with thermal adhesive (or use gallium alloy liquid pro melting point +29c as an adhesive).

I think the large surface area and high conductivity of these sheets will cause adequate heat exchange with the liquid...I will feed the circulation pump from the regions of the cpu/gpu's to cause fluid exchange there so as to prevent heat build up there.

The problem is choosing a suitable cooling liquid....mineral oil is too viscous at low temperature to pump....I would like to use something like Novec 7000 but I believe this is extortionately expensive and in any event I can't find a source in the UK.

So again I have to go with what I can get.

Hexane

http://www.reagent.co.uk/hexane?utm_...FXHLtAodLmEAaw

It's relatively cheap (compared to some of the prices I've been quoted for chemicals) has a BP of +69c and freezing point of -94c is non polar / non electrically conductive and importantly has a much lower viscosity than water.

Compared to water viscosity =1 then hexane's viscosity at -50c is 0.75 and at 0c is 0.3 so at the temps I'll be using it will be in the region of 0.5 the viscosity of water so it will pump easily over the evap.

The sting in the tail is that it is flammable, but having said that I will be able to prevent combustion by using the techniques I outlined earlier.

There will be no moving it it back and for to contain it, it will just sit in a metal sump in a sealed chamber with a saturated vapor of propane to prevent ignition. Also there will be no danger of large volume changes as could have occurred with the liquified gases.....so the liquid should just sit there safely.

This will simplify the build even further as now all that will be required is the chamber and ac unit....no freezer and recovery bottle.

Anyone have any thoughts...as I said its not a huge deviation from my original plans...just using a less volatile liquid to make it safer to use in the house.

Last edited by technogiant; 04-19-2013 at 01:23 PM. Reason: Automerged Doublepost
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Old 04-20-2013, 12:42 AM   #44
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TG, this Hexane sounds really interesting. For your build i think its going to be a lot more practical than what you were originally looking at. Theres always compromise that goes on, but i don't think you will sacrifice much efficiency using the hexane vs evapouration.

If your ideas on the pgs graphite sheets work out right you will have fantastic surface / liquid area ratio for cooling those cpus / gpus.

A few questions on the hexane, what is its specific heat capacity ? Its not combustable without ignition , eg not combustable under pressure ? I loose about 30% of waters heat carrying abilities through additives so always looking for alternatives to use. I wonder if a water / hexane mix would make for a good coolant solution ? Not for immersion obviously ;-)
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Old 04-24-2013, 02:13 PM   #45
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Yeah I think the hexane submersion will be a lot simpler and more practical.

And as regards loss of the phase change aspect of cooling there always was going to be a mixture of liquid/conductive cooling and phase change cooling and I was starting to wonder how important the phase change aspect was going to be....I mean when full immersed in liquid at -20c to -30c with a large surface area highly conductive graphite heat spreader provided I keep the submersion fluid moving it may have been that temps wouldn't have even reached the phase change temp of -12c.

The pgs graphite sheets I'm considering are 18cm X 23cm ...414 cm^2....actually double that as both sides are exposed to the liquid so 828 cm^2...even when cooling a 300w gpu that only works out at 0.36 watts per cm^2

In any event if the passive heat spreader did not prove adequate (which I doubt) I could always attach a water block over the top of the graphite heat spreader and pump submersion fluid through it and that way have both actively pumped cooling together with passive heat spreader cooling. But I'm sure provided I keep the submersion fluid moving I don't think there will be an issue as such a large surface area heat spreader will pass a lot of heat energy even at small temp deltas.

As regards the properties of hexane, I've worked out its heat capacity per ml of liquid as that will give you a more direct comparison, water is 4.2 joules/ml where as hexane is 1.5 joules/ml...but as you said your mix has a reduced heat capacity only being about 70% that of pure water so that would be 2.9 joules/ml...so your current mix has about twice the cooling capacity of hexane but is of course much more viscous.

Not sure about combustion under pressure...but I doubt pumping pressures would be a problem....in any event oxygen still has to be present which it would not be in a cooling loop....ignition source alone be that spark or compression still needs oxygen to ignite.

As regards a water/hexane mix that would not work as hexane is insoluble in water and would separate out.

You do have to be careful with hexane though as it is toxic as well as flammable.
It can be absorbed by inhalation and skin contact (ingestion can be fatal) and exposure in the longer term causes peripheral nerve damage and even central nervous system damage.

If you were thinking of pumping this in a water loop under pressure you would have to be very careful of leakage, its a low viscosity fluid and will have a high tendency to seep out through joints, and of course if it does slowly leak into your sealed chamber it will build up....and your chamber contains air!! ....it has a minimum explosive concentration of between 1 - 2%...you'd also have to be mindful of your pump seal material, from what I've seen the most commonly used seals are not compatible with isobutane and so probably also incompatible with hexane..not such a problem I guess if you pumps are submerged as leakage just goes back into the sump but outside could cause problems.

Additional Comment:

Here we go again...more changing my mind.....I've decided that handling a volatile liquid is actually more awkward than handling the gasses.....at least they come in pressure bottles and easily moved by pressure and piping....the liquid would require pouring and pumping...so I'm going the gas route as I originally wanted....no compromise

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



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.



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. Also it will cause slight pressure changes in the chamber depending on the relative heights of the heads of water in the tray and butt....those pressures will be minimal though as the max pressure head would be 45cm of water which I believe equates to 0.63 psi

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.

Last edited by technogiant; 04-24-2013 at 10:52 PM. Reason: Automerged Doublepost
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Old 05-04-2013, 09:00 PM   #46
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Hey TG.. how are things coming?

You had asked about a radiator handling 3 bar. I haven't been able to find any specs.. my guess is yes as it would be static.

I know you're set on this design but I would like to make a suggestion. I highly recommend going with a liquid chiller like Orthello77 did. A liquid chiller would be much more efficient and will open up more options for secondary phase systems inside the chillbox. Heat pipes and siphons can then be directly chilled with liquid allowing high pressure chambers to handle any refrigerant. If submersion, heat pipe or siphons don't work out as expected then you can always revert back to tried and true chilled liquid cooling.
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Old 05-11-2013, 09:53 AM   #47
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Hi Drew and cheers for the advice, yeah yours is I'm sure the voice of reason and sense, but I'm afraid when I get an idea I just have to see it through....that's just the way I roll.

I've now fully decided on the full submersion in liquified refrigerant so won't be needing rads for that after all....sorry should have mentioned but I've been changing back and fore between ideas so much even I've lost track.

I think I'll get about the best cooling possible out of my ac unit with this design, as its basically a combination of liquid cooling and phase change cooling, with the components submerged in the chilled reservoir....it doesn't get much more direct than that. With the liquid having such a low viscosity it should be easy to keep the submersion liquid moving and with the large graphite sheet heat spreader I'll be using I actually doubt the component temps will get high enough to even initiate phase change, but that's just speculation atm, one thing is for sure though if phase change does kick in it will surely stop temps rising much further than the -12c boiling point. (if phase change doesn't prove to be an important aspect of this cooling method I could always substitute the liquified gas for a something like pentane which would be liquid at ambient temps)

As regards progress well I'm still in the preparation stage, I've returned those water containers and gone for two taller water butts one being wider than the other. The smaller one will be upside down inside the other and raise up and down with varying chamber gas volumes.

I'm still making preparations to get the outhouse I'm doing this in, currently assembling one shed so I can clear the area the outhouse is going in, so actual chamber build hasn't progressed further than getting a few bits and pieces together.

Additional Comment:

While I'm continuing to make preparations for the build, still preparing to build the outhouse at the moment I'm still considering ways to adapt this build and make it better.

I'm considering quite a radical change......I was going to make the system so that the pressure in the chamber would be maintained at or close to atmospheric. My concern at that time was really that I would not be able to construct a chamber easily that could withstand high pressures necessary to contain the refrigerant at ambient temperatures....and so that led on to the devising the method for containing the liquid in a pressure bottle and making a relatively weak chamber maintained at atmospheric pressure.

But I'm now considering building the chamber stronger so that it can withstand negative/compressive forces.....I would still need to contain the refrigerant in a pressure bottle between uses but having a chamber capable of withstanding negative pressures has several advantages.

I would not use a background gas (propane), I'd simply use the refrigerant liquid/gas (isobutane) with a boiling point of -12c at atmospheric pressures.

As the chamber temperature dropped below the refrigerants boiling point instead of the pressure being maintained at atmospheric it would be allowed to drop below this and would become more negative the further from the boiling point it dropped.
I estimate at the working temps of the chamber (-30c to -20c) the pressure would be between -7 and -4 psi.

The advantage of this is that the liquid and vapor would be in a state of thermal/pressure equilibrium....the lower pressure would reduce the boiling point of the refrigerant and any heat added to the liquid would cause phase change.

This would mean that phase change cooling of the components would occur regardless of the liquid temperature as it would be continually at its boiling point due to the phase change/pressure equilibrium.
Whereas with my previous design phase change would only have kicked in at -12c. Phase change is a much more potent form of cooling and having that occur even at the operating temps of the chamber (-30c to -20c) would be a major advantage as I don't think components temps will actually go much above those temps with a submersion/phase change system.....that was certainly the case with the novec 7000 systems I've seen.

Another advantage would be I could totally remove the need for pumps, with the previous design I need pumps to pass liquid over the evap rad to cool the liquid below its boiling point of -12c and to move fluid around the components which would have in effect been liquid cooled when the liquid temps were below -12c and require circulation.

With the latest design as the chamber vapor and liquid are in thermal/pressure equilibrium then cooling the vapor by use of fans to circulate vapor through the evap will in turn cool the liquid.

Like wise as the components will be phase change cooled there will not be any need to circulate fluid over them. The agitation caused by boiling off will refresh the fluid provided I keep the heat density in terms of watts/cm^2 at acceptable levels, from info I've seen on the novec 7000 systems they use an upper limit of 6-10 watts/cm^2 before the bubbles generated actually start to insulate the component at which point you have to force circulation of liquid over the surface..... so a 6cmX6cm heat spreader would be sufficient for a 200watt component.

So I think the reasons for doing this are quite compelling....and I don't think construction of a chamber able to withstand -7psi would be too difficult, I certainly think it will be easier to make a chamber resist compressive forces rather than expansive forces.
The panels of the chamber will measure 50cm x 38cm so obviously the loads on those surface areas will be quite considerable.

I'm considering using heavy gauge aluminium plate the edges of the panels will be "stepped" and overlapped so as to resist compressive forces and sealed with heavy duty sealant. The cables and evap pipes run through tubes that will be flooded with epoxy resin to seal them.

I'd welcome peoples thoughts on this altered concept and especially suggestions on suitable designs/concepts for the chamber capable of resisting such forces as I'm not an engineer.

Last edited by technogiant; 05-11-2013 at 10:03 AM. Reason: Automerged Doublepost
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Old 05-15-2013, 10:20 PM   #48
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The forces won't be any more than those a typical freezer is subjected to. I don't think you need to go overboard on construction as far as stresses are concerned. The main thing is that it's sealed 100% when under negative pressure.

How about making the enclosure's shell out of wood, then line it with aluminum sheet and seal with some good industrial sealant. You can use alum angle on the top of the enclosure to provide a solid gasket surface for a removable top panel. You can use thinner and much cheaper alum sheet on the inside.

If you want to go with heavy gauge alum then that's fine too. Use alum angle and screws + adhesive/sealer to join the edges.
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Old 05-15-2013, 10:59 PM   #49
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Hi Drew and thanks for that, I'm glad you said that about not needing to go over the top with the strength of the build, I was considering something very heavy duty with either 1cm or 1.5cm alum plate cut to form interlocking tabs at the joins so it would resist compression and using angle over the joints to ensure they were sealed.

I may be doing the math wrong but thought this would have to withstand quite considerable forces......50cmX38cm panels at -7psi ( I worked that out from an isobutane vapor pressure vs tempurature curve and think thats correct) works out at a load of 2,000lb on each panel. Are you sure a lighter construction would be sufficient?.....it would be much easier and cheaper and I would prefer that if possible.

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Old 08-03-2013, 12:49 PM   #50
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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.
****************

Additional Comment:

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.

Additional Comment:

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.



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Like I said early days...

Additional Comment:

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.

Additional Comment:

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

Additional Comment:

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.

Additional Comment:

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.




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Additional Comment:

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.



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Last edited by technogiant; 08-03-2013 at 12:49 PM. Reason: Automerged Doublepost
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Old 08-14-2013, 02:54 AM   #51
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^ yeah ...wtf...reported as spam

Additional Comment:

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 before it set......not sure if it will be easy to get a large spread out layer of solder though?

Any ideas?

Additional Comment:

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 :thumb:

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



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http://www.youtube.com/watch?v=YflRW...ature=youtu.be

Additional Comment:

Okay so just a little update, I've been taxing my mind on how to seal the cables that pass through the chamber wall.

Sealing them externally ie the outer sheath to the chamber wall is not a problem.
The big problem is sealing them internally ie the inside of the cables other wise air will suck in through them, many have outer sheaths bundling several cables inside all of which have channels in between them.

I've even tested single wires with braided copper cores...like the power cables...they also let a significant amount if air in when gas pressure is applied at one end.

About the only things that don't leak are are single wires with a single strand core!

So I've had to think of a means to ensure they are completely sealed....the very last thing I can have is air sucking into this chamber.

So I've decided to run extenders through the wall and where they join to the next cable externally I'm going to submerge them in liquid contained in a small secondary chamber.

Obviously this liquid has to be non conductive, also it either has to be thick and viscous enough so that it can't simply be pulled through the cables like the air is, or alternatively it should freeze in the cables as they enter the cold chamber so blocking them.
It must be thick enough at ambient temps so that it doesn't track by capillary action into the chamber and mess it all up.
On top of this it must also not be affected by butane or allow its passage through it.

So not too much to ask then :-/

The best I can think of is glycerol with fructose dissolved in it, it's quite viscous at ambient temps so should not track by capillarity very easily.
Also although it doesn't freeze solid it does become extremely viscous at low temperatures and I doubt given the small sizes of the channels it would be pushed through there with the pressures being considered here.

One problem with it is that it is hygroscopic...it absorbs water from the air which would ultimately reduce its electrical resistance....but I could guard against that by pouring a layer of oil over the top of it.

Once the glycerol has been drawn into the cables I may remove it from the secondary chamber just leaving it inside the cables and then re flood the connections with melted paraffin wax.

That would set solid preventing the glycerol being drawn or tracking further in and would have no possible problem of losing its resistance by water absorption like the glycerol would.

Paraffin wax can be dissolved by butane so I couldn't just use that on it's own, the glycerol would be forming a block in the cables preventing the the butane from getting to it.

Last edited by technogiant; 08-14-2013 at 02:57 AM. Reason: Automerged Doublepost
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Old 08-18-2013, 10:12 PM   #52
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That Aluminum box is probably the most amazing thing I have ever seen on this forum. The precision on it is just amazing. Well done.
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Old 10-04-2013, 01:50 PM   #53
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Quote:
Originally Posted by @dmin View Post
That Aluminum box is probably the most amazing thing I have ever seen on this forum. The precision on it is just amazing. Well done.
Thanks, it took some doing, and because of the way it all interlocks its quite solid even without being joined by adhesive.

I'll be getting all my cable extenders through this week, once I have those in hand I'll run then through the side wall.....not looking forward to that, all that work to make a box that can be sealed air tight only to cut dirty great big holes in the side of it :-/ ....still has to be done.

Additional Comment:

Hi all, just a few lines to let you know the project is still alive and kicking.
It's been a little slower going than I'd hoped but is progressing none the less.

I've run all the cables through the chamber wall and sealed them, first attempt had a small leak so I got a polyurethane encapsulation resin, formed a mold around them and poured in to completely seal.

I've also assembled and sealed all 4 sides and the base of the box. I've put the gas pipes and valves in as well.

So it was at a point where I could leak test the majority of the box and the cable/gas pipe entry points which I did by filling with water and leaving overnight......and happily no leaks.

next stage I'm going to overlay the external joints/seams with 90 degree aluminium angle to further seal the chamber.

Then I'll be able to seal the basin into place.....those last two things shouldn't take too long but before I can progress to putting the evap in there I'll have to build the stand so that everything will be in the correct position to go together as the ac unit has to be place at a height so the evap can sit on top of the basin in the chamber.

Still shouldn't take to much longer....I'd say a month at tops

Additional Comment:

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.

Additional Comment:

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.

Additional Comment:

So just a further update....things progressing quite rapidly now.....I've just about completed the interior of the chamber now, the evap and fans are all shrouded in and I've wired up the fans and led lights to my control panel, also secured the camera in place so will hopefully be able to get some video of it operating at some stage...I need to secure the fee end of the stainless steel fluid transfer hose in place at the bottom of the basin and that's it for the internals.

I'm going to test the pc in there using all the chambers cables etc before I swap out the standard cpu heat sink for an adapted one...but once I've done that I'll be sealing the lid on.

I've bought my oxygen free nitrogen cylinder regulator and connections that will enable me to purge the system of any oxygen. I've also bought my 13 kg propane and 15kg butane cylinders together with a freezer for the fluid recovery process.

I'm currently burning off all the propane as I don't need that...only wanted the cylinder.

Hopefully within the next 2 weeks I'll have completed everything and be purging the system and loading with refrigerant.

Additional Comment:

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?tp...=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.

Additional Comment:

Right....in the end I decided against the coating, I've put the heat sink on there without the fan....I've also removed every other fin to widen the fin spacing so that bubbles are less likely to get trapped/retained in there.

I was not confident I could match the enhanced evaporation coating that Novec 3M cooled systems use and may have made heat transfer worse if my coating was too thick.

The bottom line is that regardless of the coating there is an upper limit for heat transfer with passive boiling off of 6-10watts/cm^2 above that the bubbles generated insulate the component.

The surface area of my 2700k is 3.7x3.7cm = 13.7cm^2 so 82 - 137watts of heat dissipation is possible....so basically regardless of the coating the heat density of a highly oc'ed 2700k would be too much for the surface area.

So I'd have to use a heat sink to reduce the heat density...going straight IHS is not possible.

Having decided that a HS is essential and given that the area of the HS I'm using is about 30X the area of the IHS then the requirement for having such an efficient coating is removed.

They quote a 15X increase in cooling through use of the coating as compared to bare copper....but I have 30X the surface area....so even without the coating this could transfer twice the heat of the coated surface....additionally I won't run into too high heat density problems.

A problem with using a HS is that you need a TIM and they wash out in submersion systems.

I can't use some liquid metals as they contain Gallium which could damage my aluminium chamber. (but may try Indigo extreme at a later date)

So perhaps controversially I've used a home made TIM.....syrup mixed with alumina powder.

It won't dissolve in the fluid and at low temp it will be very viscous and mechanically not wash away.

I've been testing the this TIM on my system for the last month....it seems better than Arctic silver 5 and didn't dry out after blitzing every day with intel burn test and prime 95.

Finally my freezer has been delivered and I've been able to do a little proof of concept as regards the cold line transfer procedure for recovering the fluid from the chamber basin to the pressure bottle.

I'd previously emptied a propane cylinder which is needed to contain the liquid butane used for submerion and needed to transfer the contents of a full butane cylinder to it.

So I placed the emptied propane cylinder in the freezer and connected it to the full butane cylinder which is at ambient temp.
Turn the butane cylinder upside-down and open both bottle valves...the pressure in the warmer butane cylinder will start to push the liquid phase into the empty cold cylinder as the pressure in the cold cylinder builds then the vapor phase liquifies as it is cold and under pressure so making more room for more liquid to enter.

In all I wanted to transfer 10.8kg of liquid butane across which equates to 18 liters.(full capacity is 26 liters)...it was a complete success

On a safety note there is no concern that I may overfill the cylinder as both have the same capacity (they should not be filled more that 80% with liquid)

Also I was careful to purge the connecting pipe with butane first so that I didn't transfer air into the bottle...also as a belt and braces approach after I have finished the transfer I purged off some of the contents of the refilled cylinder which would remove any air that may have got in...although tbh this is unlikely to have occurred.

So won't be long now, the end is insight, tomorrow I'll be putting the mobo into the chamber sealing the lid on.

Then just insulation boarding the outside, joining up the purging system bits and pieces, connecting the external cables and sealing those and I'll be ready to purge out the system and start leak testing.

Last edited by technogiant; 10-04-2013 at 01:50 PM. Reason: Automerged Doublepost
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Old 10-06-2013, 01:55 AM   #54
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Exciting stuff TG. Theres nothing like the first few times you start up .. and the dramas that follow - hopefully not too many. Its going to be interesting in a sense as you won't be able to see the components inside , if all goes well you won't need to anyhow. I'm sure you will pull this off !!
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Old 10-06-2013, 02:33 AM   #55
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Hi Orthello, Yeah I can't wait to get this running now....it's been too long in the thinking out stage.....time for action and results.

Then again considering what I'm doing it needed a lot of thought....I really don't want any dramas as they are likely to be big ones.

I got my mobo in the chamber yesterday tested it and then sealed the lid on....so your right.....nothing to see but a grey aluminium box...lol.

I have got lighting in there though and I've got a web cam in there too so I should be able to get footage of the components boiling off and the filling/emptying process in action. (assuming the web cam holds upto the low temp in a low pressure environment of butane vapor :-/ )
I will need eyes on so I can see the fluid level is correct, although I guesstimated about 18 liters will do the job and that is what I transferred into the pressure cylinder I may have to top that up......but once I know the level is correct and the fill empty process works then I should beable to pretty much use it blind.....but it will be cool to watch it in action none the less.

Here's hoping to luck that it works out.

PS hows your system holding up...pump problems completely solved by oil submersion?.....and what about the TIM issues...any developments there?

Last edited by technogiant; 10-06-2013 at 02:52 AM.
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Old 10-06-2013, 04:47 PM   #56
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Ahh good idea on the web cam , good stuff , chuck that video up on you tube once you get it going , be great to watch !!

Unlike mine yours will be quite the spectacle , I just see a bit of ice on the outside of the gasket that's the indication that's its freezing inside (+ temp sensor).

Pumps are faltering again , yet this time I think its due to old age. All of the pumps in submersion were ran un-submerged for some time and suffered some degradation because of it. One was outright faulty before it got dunked in the vegie oil (but came back to be pretty solid for a while). I'm building a new pumprack atm. The goal is 4 l/m+ at -25c. (at about 3.3 now). 5 PMP 500s in series with variable voltage control through 7vdc - 16 vdc. I'm hoping to get more life out of the pumps by undervolting them 80 % of the time (the time i'm not benching or gaming). I'll have some pics up soon.

Tim has degraded, not much i can do about it , the degraded performance is still likely better than the alternatives, the heat spring looks interesing, i'm just not sure the core will handle enough pressure to push it past the current performance i'm getting from Liquid Pro. Nothing ideal at this stage. I need a liquid metal with a melting point out of the range of this chiller temperatures ideally.
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Old 10-07-2013, 12:40 AM   #57
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Wow 5 pmp 500's in series.....that's some some impressive pumping power there....hope running them under oil from the start and undervolting pays off for you.

I seem to remember you were having good results from a diaphragm pump...unless I'm misremembering.....but it was very noisy....if you were to put that under oil would it not damp the sound out?

On the TIM front I'd give Indigo extreme a go.....once you've gone through the initial burn-in process it remains solid....it's the constant phase change from liquid to solid is causing the degradation of your current TIM....worth a try any way.

As regards my project I've cut all the insulation board to size...but got commitments this week now so cant do much till the weekend...but hopefully towards the latter part of next week I'll be testing.
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Old 10-09-2013, 02:26 AM   #58
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The dual diaphragm pumps were powerfull but very noisy , thats not a bad idea to try and drown them out. Its their vibration thats the killer, very much like a two stroke motor. I would have to try to isolate the vibration more but its difficult as the piping connects to the pumps and the piping goes through the window pane which enhances any vibration. Hopefully mark II with the new pump rack will fix things with longevity long term, especially the undervolting should save a bit of power too and increase lifetime. If i can go a year without a pump failure i will have cracked it .. I've run about 4 months on the current pumps , and only 1 pump is intermittently faulty (and it ran outside of the oil for some time prior) so not too bad going , i think the concept of submersion is sound.

I tried that indigo extreme couple of times, it never fluxed for me. Eg it never melted in place properly . Maybe i had a dud batch. I'll give it another go once i've finished these mods.

Can't wait to see how your testing goes ...
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Old 10-19-2013, 01:11 PM   #59
technogiant
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Quote:
Originally Posted by Orthello77 View Post
.....i think the concept of submersion is sound.
Yeah I'm sure it will be fine with new pumps under oil from the start.....and the under volting is bound to help

Quote:
Originally Posted by Orthello77 View Post
I tried that indigo extreme couple of times, it never fluxed for me. Eg it never melted in place properly . Maybe i had a dud batch. I'll give it another go once i've finished these mods.
That's the reason I've shied away from it...I don't want to cut the chamber open and then re-seal and re-purge to start with just because the TIM didn't flow.

I want to use something I know will work for initial testing....although the longevity of my home brew syrup/alumina may be questionable, I know it works in the shorter term of months and will be able to test for degradation.

When I upgrade my gpu's (probably next year at 20nm) I'll have had plenty of time to acquaint my self with the system and may try the indigo Ex then....that will also give me a long term test of the syrup/TIM as I'll have to use that on gpu's unless I used thermal epoxy or expensive heat springs.

Lol...I've gone from a system that was not compatible with heat pipes to one that's not compatible with commercial TIM. :-/

Additional Comment:

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

Additional Comment:

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.

Additional Comment:

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.

Additional Comment:

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.

Additional Comment:

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.

Additional Comment:

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.

http://www.youtube.com/watch?v=Ms7On...ature=youtu.be

Additional Comment:

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.

http://www.youtube.com/watch?v=ZUVWAdSnYuw

Just some video of the full chamber bubbling away again...enjoy I'll be posting up some tests/temps in a few minutes.

Additional Comment:

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



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



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.



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





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.

Last edited by technogiant; 10-19-2013 at 01:35 PM. Reason: Automerged Doublepost
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Old 10-19-2013, 10:56 PM   #60
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Wow ... Some pretty sick results there TG !!! loving the videos. Sandys can be quite stubborn , eg my 2700k wouldn't boot at 5.5 no matter how cold 5.475 was bootable etc just not 5.5, 5.6 got to the same point as 5.5. You might just have hit the brick wall with the 2700k, hopefully not. It should be more stable in IBT at closer to 5.5 now. Those GPUs should be good for some higher clocks though, i mean 50c to 6c !!! thats a wopping drop there. I wouldn't be surprised if there was 50-75 mhz more under the hood there now. Only problem is nvidia in their wisdom may have put a clock lock in there at 1000 mhz ... just like my 580s ..

lol about standing behind the wall and turning the switch on ... the things you do in the name of exteme cooling , i had those feelings siphoning methanol trying to blead that LG pump first time round lol ...

Congratulations, i'm sure you will tweak it from here. Considering you are not putting a watt of extra cooling into this from your chillbox and its all coming from efficiency of direct submersion cooling the results are outstanding.

Last edited by Orthello77; 10-19-2013 at 11:10 PM.
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