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Author Topic: Submersing a rig  (Read 4963 times)
Defkin
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January 25, 2012, 10:35:59 AM
 #61

I think you might be surprised how much heat a metal surface area can transfer with liquids on both sides.

Its no different than with a submerged radiator. Assuming your ammo box has equal thermal transfer characteristics as an oil cooler, which I doubt considering the thickness, coating etc, all that matter is surface area and temperature difference between the liquids.  A radiator has a huge surface area for its volume, while with your approach, surface area is directly linked to the amount of oil and scales rather poorly with it (cubic root) .

Mind you, Im not saying it wouldnt be enough but I fail to see the advantage, particularly since I wouldnt be able to flow nearly as much water through the "containing container", so Id have higher water temps.  The rigs will be above pond water level, so I cant use gravity feed, I need pump fed. Since you cant pressurize the container, you need gravity return. Unless I plumb at the very least 50mm water return pipes to the shed, thats going to be a serious limitation on flow rate or cause headaches with the water level. To give you an idea, I use 130mm return pipes in my filter, and with my pump capacity even that creates a 10+cm increase in water levels in the filters. Now I dont think youd need anything like the kind of waterflow I have through the filters, but it sure doesnt hurt, and I already have it, so why not use it? The higher the flow, the lower the water temps.

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I am trying to picture what you are going to do. Are you only putting the cards into the pond if so how will you protect the MB and PSU etc?

Not sure what you mean by protect. Protect from what? Take a motherboard with a few gpu's (probably using extender cables), turn it upside down. Drop the cards in an oil bath. Even if oil would splash on the MB or PSUs or, or the oil creeps up, it doesnt matter. Ill probably prevent this by creating a lid over the oil box though, mostly to prevent dirt from getting in.  I will wire the cables through the lid and seal it (and may use PCIe power extender cables that are fixed in the lid, so the psu cables plug in to the lid), but thats not even necessary.

Sorry I had this picture of a PC hanging from a tree (little birds nesting on it) GPUs hanging down from it into the pond......


Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

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January 25, 2012, 10:59:55 AM
 #62

Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

I see no reason why that wouldnt work, but boy, sure sounds a lot more complicated than buying a $40 oil cooler. In either scenario you still need tubing, a pump, oil container etc. It would also take up even more space in my shed for no apparent advantage. Perhaps if you have a water source and no filter or pumps to use, then your approach might make sense, though Id probably still prefer to just put the radiator straight in the pond or swimming pool or whatever.

Also dont underestimate how difficult it is to make a pressurized vessel of any kind. Ive had a smallish commercial pressure filter once, with a 19mm in and outlet.
when I accidentally hooked up the wrong (too powerful) pump, it exploded. Water pressure is nasty.

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January 25, 2012, 12:36:44 PM
 #63

I just did a small test, mixing vegetable oil with light paraffin oil; the parafin oil does float on top, but if you stir the fluids thoroughly, it seems to mix. An hour later I cant really say I see a layer of parafin oil floating on top. Bummer Sad.

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January 25, 2012, 11:10:40 PM
 #64

ever think of just keeping the side panel off when you run it?
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January 25, 2012, 11:51:38 PM
 #65

ever think of just keeping the side panel off when you run it?

Lol. I might try that, if there were any side panels. Or top or bottom Smiley

Defkin
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January 26, 2012, 01:15:59 AM
 #66

Ok so how about this. Take a 44 gallon drum and flow the water in/out, pressurize it. Weld a metal well into the drum to seat the GPUs in an oil bath. The welding would be a little more fiddly and you would want to give it a good hydrostatic test but there is no reason you couldn't do it length ways with the drum on its side. You could also weld fins onto the bottom of the well to maximize surface area.

I see no reason why that wouldnt work, but boy, sure sounds a lot more complicated than buying a $40 oil cooler. In either scenario you still need tubing, a pump, oil container etc. It would also take up even more space in my shed for no apparent advantage. Perhaps if you have a water source and no filter or pumps to use, then your approach might make sense, though Id probably still prefer to just put the radiator straight in the pond or swimming pool or whatever.

Also dont underestimate how difficult it is to make a pressurized vessel of any kind. Ive had a smallish commercial pressure filter once, with a 19mm in and outlet.
when I accidentally hooked up the wrong (too powerful) pump, it exploded. Water pressure is nasty.

I was under the impression you had the pump and water flow already (pond filter) needing only a 3/4 inch (garden hose) bypass setup 20-30 psi. As for the rest I guess I was looking at my shed, the drum and scrap is sitting there....although I would have made a purpose built heat exchanger out of the same junk pile.

Have you considered having a fridge evaporator submerged into the oil? More power used but better cooling/control. I have the vac and reclaim gear so maybe not an option if you don't have access.

in your diagram you have not shown how you planned to pump the oil to the oil cooler. Also missing is the number of gpu you need to drown i.e. min dimensions of oil container need to house the gpu.

As i see it your issue currently is the amount of oil required? What if you submerged the oil cooler in the oil and pumped the water though it. This would mean that the water side is an open loop and would need cleaning every so often....

 
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January 26, 2012, 08:20:38 AM
 #67

Have you considered having a fridge evaporator submerged into the oil? More power used but better cooling/control. I have the vac and reclaim gear so maybe not an option if you don't have access.

No. Though I see no reason it wouldnt work, Id still be dumping the heat in the shed where I dont want it, and not in the water where at least it has some uses. Also I dont have a spare fridge and its very bulky and probably beyond my skills.

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in your diagram you have not shown how you planned to pump the oil to the oil cooler. Also missing is the number of gpu you need to drown i.e. min dimensions of oil container need to house the gpu.

I would pump the oil with a ... pump Smiley. You could use most water pumps, if it can pump water, it can pump light oil. A large aquarium pump might do the job, but overheating is something to pay attention to. I dont know how hot the oil will end up being, but assuming 50+C, thats not something all pumps will like. So , Im looking at this pump:

http://www.ebay.co.uk/itm/High-temperature-100C-Water-Oil-Pump-w-speed-Control-/160526138814

As for the number of GPU's; I only have 5 atm, but I plan on expanding that in the coming months. Im waiting for HD 7xxx0 cards to go mainstream and hoping 5xxx cards will become cheap secondhand.  But for now, I started work on a small bath that will hold 4 or 5 gpus max. Depending on temps I get, I might scale that up, possible by "daisy chaining" several oil baths using the same single pump and radiator or add more if need be.

But I actually suspect the above pump combined with a car or motorcycle oil radiator will be overkill for 10 cards, it might handle 100+ cards. After all, the oil radiator on my bike is no bigger, its only air cooled and my bike produces 80+ KW of power. Granted not all of that heat is dumped in the oil, but much of it is.

But Ill only know for sure when I have tried.

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As i see it your issue currently is the amount of oil required?

Its a concern yes, certainly if I wanted to use pure mineral oil. All I have found here is hideously expensive. If you live in the US, this would seem good and cheap:

http://www.amazon.com/Durvet-Mineral-Oil-1-Gal/dp/B000HHLUE6

Ive not found anything remotely that cheap here.

For vegetable oil, its not much of a concern, its really cheap, though it will also depends how long it will last before it needs replacement. If it ever needs replacement, who knows? I dont Smiley.

 Since the amount of oil would have no real impact on the temperature theoretically, I plan on minimizing the amount. Currently working on a small 25L prototype. When my extender cables and a spare motherboard+cpu combo arrive I will plunge in a single old nvidia card with no oil cooling just to see what happens. If it doesnt overheat with just a single ~100W, I may even keep that running for a few months  to see how the videocard, fans and the oil cope.

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What if you submerged the oil cooler in the oil and pumped the water though it. This would mean that the water side is an open loop and would need cleaning every so often....

Pumping dirty pond water with leaves, needles, fish poop, gunk, algae and what have you through a radiator is asking for trouble. Its gonna clog in a matter of days, at most weeks. I see what happens in my filters, its not pretty.  

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January 26, 2012, 04:16:10 PM
 #68

I wish you luck P4man.  Nobody has yet produced a oil cooled setup which is more cost effective than traditional water cooling but you access to a massive heat sink (pond) means you might be able to.

Your concept is the first that at least on paper makes me say "hmm" that might work.  The largest barrier is the high cost of mineral oil.  I almost wonder if some single GPU container would make sense.

To visualize.  Imagine a container (no top) which is roughly the size of a single graphics card.  If you have 4 GPU on  a board you set 4 of the containers side by side, turn MB upside down so the GPU are hanging into the 4 smaller containers.  Now you get a 4 way manifold and run 4 tubing lines to the 4 containers, opposite side of container has an outlet where 4 lines connect to a manifold again. 

A parallel cooling setup.  While more complicated if it saves you a gallons of mineral oil on each rig that savings could be worth it.  The large problem is graphics cards are "tall" (say 5").  If you have a large single pan (12" by 8") and you need to have 7" of depth you are talking 3 or 4 gallons. 

Some more "volume efficient design" (say 7" by 3" by 8") may allow you to use only half a gallon per card (plus amount in the loop).

You may still want to consider a heat exchanger if you need to pipe the cooling fluid a long way to the pond.  Having a short "oil loop" for each rig and then all rigs connected in parallel and then dumping that heat into a heat exchanger for a long range water loop to the pond would reduce the amount of oil you need. 

If cost of oil in long distance loop > cost of heat exchanger well you are golden.  A more expensive setup would be 1 heat exchanger for each rig connected to a single long distance water loop to the radiator in the pond.  The nice thing about using an exchanger is it would require 2 leaks to pollute your pond.
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January 26, 2012, 04:28:35 PM
 #69

I almost wonder if some single GPU container would make sense.

or how about.... no container at all? I just saw this:

http://www.youtube.com/watch?v=okVPiYD7ny8

Thats nuts. He is not even using a heatsink on his Pentium4, just spraying the oil on it Shocked

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You may still want to consider a heat exchanger if you need to pipe the cooling fluid a long way to the pond.  Having a short "oil loop" for each rig and then all rigs connected in parallel and then dumping that heat into a heat exchanger for a long range water loop to the pond would reduce the amount of oil you need.  

If cost of oil in long distance loop > cost of heat exchanger well you are golden.  A more expensive setup would be 1 heat exchanger for each rig connected to a single long distance water loop to the radiator in the pond.  The nice thing about using an exchanger is it would require 2 leaks to pollute your pond.

Hmmm... food for thought.  Though it would also require  a second pump doubling the potential points of failure and further increasing costs.
But if I go ahead with this, Ill almost certainly go with vegetable oil, and that makes the cost a non issue. Local supermarket sells frying oil for 1 euro per liter and its very liquid, almost water like. It might go bad in months, but I read people running their rigs in aquaria (so with light oxidizing the oil)  for 18 months without changing their vegetable oil, so who knows.

BTW, Im bidding on a Formula 1 transmission cooler that used to be in Michael Schumacher's Benetton LOL:
http://www.benl.ebay.be/itm/350525626493?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

3 days to go, Im sure it will go too high and Ill buy something more sensible but it would be fun Cheesy


Defkin
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January 27, 2012, 06:47:34 AM
 #70


http://www.petrochemcarless.com/white-oils.htm
I don't know where you live but you may want to try this place for the oil?


If I was going to build something like this here is what I would do assuming of course I had a pond Cheesy

I would use a 240v recirculating pump (have it) and a car radiator (have it) and make the exchanger out of 10mm plate (have it). Only thing I would have to buy is the water hoses, steel pipe and the oil.
 



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January 27, 2012, 09:06:05 AM
 #71

@Defkin
I dont have the metal working skills to make something like that work. I dont have any hand working skills really, so thats no surprise Smiley. I also think you have a lot of work to achieve relatively small heat exchange surface. And Id still be hesitant to pump pond water through it. All kinds of things are going to live in there and accumulate. Ever seen a string algae blossom?

@DnT and everyone
DnT gave me another idea with his "single gpu container" approach. Its too much work as he put it, but there is an easier alternative that achieves almost the same. Im thinking of making slightly oversized mockups of my videocards with some room for oil flow, position them in the PVC container, and fill it with polyurethane foam.  It will help keep the cards in place, drastically reduce the amount of oil I need, and can help directing the oil flow. I could also embed some tubing to deliver the cool oil right at the fan intakes and remove the oil at the exhausts. Its a bit of a hybrid approach between the video I linked above (splashing oil on the hot components) and DnTs suggestion.

Now Im not entirely sure if PUR foam will resist being submerged in oil for extended period of time. I fear it may not. I know water eats it away slowly (we are talking years, but still), so I may have to coat the hardened foam with something. I have some fiberglass and epoxy raisin I could use, though perhaps just coating it with some kind of oil resistant paint or sealant might be enough. Suggestions?

Im also wondering how to make the mockups and be able to remove them without tearing up the PUR foam. Or maybe I should just fill it with foam and carve out the areas with a dremel or something. Im not much of a handy man so suggestions are welcome Smiley

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January 27, 2012, 09:42:07 AM
 #72

I don't think Defkin intended to use pond water in the "water loop" because his post indicated using a pump and radiator he has. 
So it would be oil box -> water loop -> radiator in pond

Also you likely don't need as much surface area as you think.  Remember air is an utterly horrible heat transfer mechanism.  Radiators have massive surface area because air is so friggin bad. 

Thermal conductivity:
Air 0.025 W/(m*K)
Mineral Oil 0.138 W/(m*K) <- 5x higher
Water 0.600 W/(m*K) <- 24x higher

The effective difference is actually much higher because air density is so low it takes a much larger fan/pump to move the same amount of material.

So radiators have such high surface area due to two properties of air:
a) moving a lot of air is difficult
b) air is such a poor conductor of heat

So for an equal amount of working fluid you could get away w/ 1/5th the surface area relative to an air-radiator design.  In reality you could get away with maybe 1/20th because you could simply pump working fluid faster.   As a practical example in those links I had above for heat exchanger are flat plate exchangers and they have much surface area than an air-radiator design.
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January 27, 2012, 11:12:20 AM
 #73

DnT has pretty much nailed it with what I was doing. Cutting and welding metal for me is easier to do than any other material such as wood and even cardboard for that mater. It is perfect for heat exchange, in fact most of the difficulty working with it is due to heat exchange. But as you don't have the skills or equipment.......being such a small simple job it might be worth getting the local workshop to do it but that would prob exceed your budget.


Anyhow back to the idea you and DnT were working on. How are you with fiberglass? I don't like it much because it is messy and makes me itch but it is probably ideal for individual covers and it is cheap. You can make a mold out of a block of wood and waxed paper.

Expanding or simplifying the idea DnT suggested you could make the containers and fiberglass them into a tray made from ply wood. Have small holes in the base of each container and flood the tray with oil. The oil will fill the containers and drain out of the holes. Adding a large hole on the tray at a higher level will allow you to crank the pump up until it goes down this overflow thus giving you a uniform flow of oil through each container.

The real beauty of this idea is that if you ever give up mining, with some seeds, hydroponic solution and a grow light you have a ready made indoor hydroponic system and a brand new hobby, lol

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January 27, 2012, 11:20:35 AM
 #74

That more or less boils down to what I intend to make, except, I dont like so much air. Too much chance of dirt getting in the oil. So fill most of the air in your drawing with PU foam or similar, and replace the freeflowing oil with some inserted tubing and its roughly the same idea. Only I dont have to worry about the pump capacity to maintain levels.

Im okay with fibreglass btw. Its messy, but I love the stuff. But its not as easy as youd think to make it water (well, oil) tight. Ill experiment a bit tonight.

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January 27, 2012, 11:34:49 AM
 #75

If you do it, please post a picture here as well:
https://bitcointalk.org/index.php?topic=7216.0

Me interested as well. One friend of mine tried submerging a power supply in oil, ended up heating the whole  bath because of no radiator.

"Emergencies" have always been the pretext on which the safeguards of individual liberty have been eroded. (F. Hayek)
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January 27, 2012, 12:15:37 PM
 #76

I will. But dont hold your breath. Im really slow (and not even very thorough) when it comes to stuff like this Smiley

My current plan of action; make a mold of sorts in a PVC tub, that will keep me busy for a while; then fill it with vegetable oil, insert a single spare old ~100W nvidia gpu with no oil circulation or cooling (other than the gpu fan). See what happens. I want to see the difference between oil temperature and gpu temps. I want to see how fast the oil heats up, and if that is local heeat, close to the card or if the entire bath slowly heats up.

 If the oil gets hot but without causing the card to really overheat, that would be perfect and Ill keep it running for some time to see the effects on the oil, the card, and measure temperatures in various places in the oil bath. With low ambient temps and a fan if needed, I hope to get there. 70C or so oil temp would be perfect as a worst case test scenario.

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January 27, 2012, 12:59:55 PM
 #77

That more or less boils down to what I intend to make, except, I dont like so much air. Too much chance of dirt getting in the oil. So fill most of the air in your drawing with PU foam or similar, and replace the freeflowing oil with some inserted tubing and its roughly the same idea. Only I dont have to worry about the pump capacity to maintain levels.

Im okay with fibreglass btw. Its messy, but I love the stuff. But its not as easy as youd think to make it water (well, oil) tight. Ill experiment a bit tonight.

The tray only has to be big enough to accommodate the cards and a channel big enough to deliver oil to the containers and overflow. Even then you can eliminate most of the surface area by raising what parts you don't need above the oil level.
                                                               
The pump control is easy just put in a bypass, place a valved connection between inlet and outlet, adjust valve to regulate flow.

I don't have any probs making fiberglass waterproof, try thinning the resin with acetone.

With this design I would be wary of the fire hazard, it would be bad enough with fiberglass I wouldn't want to go near PU foam. You will need a fail-safe shutoff switch in case the oil pump stops, you can make a relativity bullet proof one out of a mirco switch and a syringe.




P4man
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January 27, 2012, 03:51:57 PM
 #78

All oil is flammable, so Im not sure what risk the PU (or fibreglass) would add to that. If it catches fire, my shed will burn down anyway. But in case the pump fails, the cards will just shut down, and long before the oil reaches flash point.

Anyway, while I appreciate the thoughts and drawings, Ive pretty much made up my mind. Unless experimentation throws up some unexpected results, I will be using a single PVC container that will hold the cards (im building the first to hold 6 with 2 motherboards), pump, oil and PU foam (if needed, coated with something, perhaps just some oil resistant primer paint). The oil will be circulated to the radiator in my pond filter.  There is no risk in it running dry unless I have a leak, or overflowing, and its a fair bit easier to set up, not too mention more compact and easier to move.

Ive just filled a tiny plastic cup with PU foam and vegetable oil that I will keep an eye on to see if it breaks down. I suspect it will, but hopefully only in the very long run. Once hardened, PU is supposed to be pretty inert.

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January 27, 2012, 04:46:46 PM
 #79

I'm a bit of a motorcycle gearhead, so I'm really curious about repurposing a wrecked oil cooling system for laughs.
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January 27, 2012, 04:54:51 PM
 #80

I'm a bit of a motorcycle gearhead, so I'm really curious about repurposing a wrecked oil cooling system for laughs.

I hear ya. Among others, I still got an old (oil cooled!) GSX750F in my garage. Its no longer in driving condition, been thinking about lending that oil cooler.  But  Im worried it might be corroded and contain lots of metal particles. Think its safer to buy something new.

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