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CPU Convective Water Cooling
biso writes "The possibility of cooling a CPU with gravitational convective flow of water is here analyzed and experimented with positive results.
Many liquid cooling systems have been experimented by overclockers to better dissipate the heat from CPUs. The major part of these coolers is characterized by a relatively complex system requiring pumps or other active devices. Sometimes even liquid nitrogen is used. I built a simpler cooler, able to dissipate the same heat flux of a normal heatsink."
He's going to be boiling noodles in a minute
Banaaaana!
Yes, but can I use it as a cooler at soccer games? THAT would be the day technology is far too self-serving...
Da comp cant tell u da emotional story.It can give u da exact mathematical design,but whatz missin is da eyebrows. -FZ
ok, i can see the extra bit of silence from not having a pump would be nice. but ... isnt a bowl of water on top of your computer just asking for trouble? something tells me this guy doesnt have cats.
...and one i've had for a long time. This must be the first person with any guts to try it out though. Must also be the first person I know of to balance a bucket of water on top of an open computer...
Feel that power? That's mah MOUSING FINGER
I've built numerous different water cooled systems, and the $20 pump from the aquarium supply place is NOT the most complex piece. A good waterjacket for the cpu is by far the most complex and generally most expensive single piece, and also the one that is most critical for good performance. Still need the waterjacket in this design, so it isn't really saving anything...
It's cheap, reliable, odorless and environmentally friendly, and refills are available everywhere. I myself have been using a 78% nitrogen gas mixture at 14.7 PSI to cool all my computer components for years now. Where did I get the idea? I guess I just pulled it out of thin *SMACK*
I really think that phase change cooling systems are the future of the PC. Only with phase change cooling systems do you get high quality cooling able to remove the utmost heat away from a CPU and cool it to below freezing.
I saw a presentation by Intel last year in which it pointed out that modern CPU's emit more heat per area than molten lava, and they expect that within a few years they will emit more heat per area than the sun.
With these considerations passive water cooling is only a good first step and bound to be insufficient, even over the short term.
Abstract
The possibility of cooling a CPU with gravitational convective flow of water is analyzed and experimented with positive results.
Introduction
Many liquid cooling systems have been experimented by overclockers to better dissipate the heat from CPUs. The major part of these coolers is characterized by a relatively complex system requiring pumps or other active devices. Sometimes even liquid nitrogen is used.
My intent was instead to build a cooler able to dissipate the same heat flux of a normal heatsink, but without the annoying noise of the fan.
A first prototype was built out of a regular heatsink. Holes were drilled in the aluminium finning, and copper tubes passed through them. An aquarium pump provided the necessary pressure for circulation.
Figure 1. First Prototype--Front View
(picture)
Figure 2. First Prototype--Side View
(picture)
The system was silent and reliable. But with bigger pipes and a lower pressure drop would it have been possible to take away the pump? Simple calculations showed that it would have been perhaps feasible and a prototype was built.
Temperature on Heatsink Surface
Roughly:
Power to be dissipated: powd = 80 W
If the heatsink is a little copper box to put over the CPU, a reasonable value for the surface available at copper-water interface can be: surfc = 0.01 m2
The heat transfer coefficient on the water-copper boundary layer can vary from a few watt per square meter per kelvin if the flow is slow and laminar to more than 1 kW K-1m-2 when the flow is very fast and turbulent. If the coefficient is supposed to be: texc = 100 W K-1m -2
The difference of temperature on surface will be: delt = powd / (texc surfc) = 80 K
It appears that the water should boil on the surface of such a little heatsink, but radiation wasn't taken into account and the geometry of the box is complex, so it's not clear if there could be turbulence and with which effect. If necessary the surface could be enhanced with fins or by increasing the dimension of the equipment.
Convection
Supposing that the heatsink could be able to exchange the heat between the CPU and the water, would it flow through the pipes?
Power to convey: powd = 80 W
Length of the circuit branches between the CPU and the radiator on the top of the computer case: heigh = 0.8 m
Equivalent length of the circuit (we take into account the bends too): len = 2 m
Radius of the pipe: rdp = 9 10-3 m
Rate of change of water density against temperature: dct = 0.55 kg m-3 K -1
Water density: rho = 103 kg m-3
Water viscosity: eta = 10-3 decapoise
Specific heat of water: wsh = 4180 J kg-1 K -1
Gravitational acceleration: grav = 9.8 m s-2
Pi: pi = 3.14
Difference of temperature between ascending and descending branch: deltat
Difference of density of the water in the two branches: deltarho = deltat dct
Difference of pressure due to the difference of density: deltap = deltarho grav heigh
Volume of water conveyed per unit time: vot
Pressure drop in the pipe: deltap = vot 8 eta len / (pi rdp 4)
Power conveyed: powd = wsh rho deltat vot
Putting it all together: deltat2 = 8 powd eta len / (wsh rho pi rdp 4 dct grav heigh) = 3.4 K2
Everything should work with a temperature difference of less than 2 kelvin. Consequently the radiator isn't required to be very efficient.
SIRPAL-1 Prototype
The SIRPAL-1 prototype was made using a 5 mm thick copper sheet for the base, and 2 mm thick copper sheets for the walls. The edge of the square base is 55 mm long. Inside there are two plates 25 mm wide. One is vertically aligned, soldered to the base, to increase the exchange surface near the CPU, the other is horizontal, soldered between the input-output pipe fittings, to guide the fluid in the right direction.
A test was performed on a K6-2 450MHz which dissipates a power of about 25 watt. The ambient temperature was 18 celsius degrees. After a few hours the CPU temperature, measured by the PC board sensor, was at least 1 kelvin lower than when the fan is used. External surface temperatures: 19 celsius degrees on the pipes; 24 celsius degrees on the copper box.
A drop of ink in the water revealed a slow flow as expected. It worked so well that I think a more powerful CPU would be efficiently cooled too.
Figure 3. SIRPAL-1
(picture)
Figure 4. SIRPAL-1--Testing
(picture)
...using sponges as sound dampening material inside the case. Who knows, it just might save your computer when somebody bumps the frickin' table and dumps that bowl full of water over everything!!
Didn't I see that figure 3 photo in Die Hard with a vengance?
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heh, that picture of a bowel of water on top of an open pc tower case is not something I would necessarily run, but I would imagine that you could make the system safer by enclosing the bowel and lines and perhaps passing the lines in through an empty PCI slot bay..
Still I would imagine you might need more space to accomplish this sort of solution. Has anyone looked into stirling engines as a method of heat transferal? They have no moving parts and are reportedly fairly effecient. I have been looking into using them to harness solar power.
Trasformer oil is insulating and would not short-out anything. It could also cool the powersupply at the same time, without the inherint saftey risk water subjects us to.
...powered by water (or even antifreeze) could conceivably do two jobs: provide cooling for the cpu and produce power. It wouldn't have to be all that big either. It might not produce that much power, but probably enough to light a small desk lamp.
So far left, I'm right.
It's kind of ironic istn't it that CMOS PCs will eventually need the same plumbing as the TCMs they were supposed to replace.
Hey I had a 9021-721 MVS/ESA mainframe that used TCM's cooled by a 400psi cooling system. The great thing about the next gen CMOS mainframes was that even though one TCM was now replaced with 3-6 CMOS units, we didn't need a massive chiller system.
Oh well, guess everything will have huge ass chiller pumps now.
While I admire all of those who are willing to actually pipe water into their computers for the sake of keeping them cool, I am still more than a little frightened of this idea. Knowing me, something would end up leaking (probably through fault of my own) and my precious tower would go up in a ball of flame or some such. Rather, I choose to take your regular old air cooling and make it more effective. Through proper cable management, good airflow paths, a set of nice quiet fans, and the ability to control them with respect to how much they are needed, I keep my fan almost as cool as a friend of mine who does have a liquid cooling system, and with very comparable noise levels. If you're willing to do some work and set up a decent air-based system (and be willing to clean out the dust), there's no need to balance a bucket of water precariously on top of one's computer... : |
Yeah, and other times they go a little nutz and use Fluorinert
Heat sink and fan, such a nice and simple system, is best when you touch the heat sink wrong and can get a nice burn!
Help Brendan pay off his student loans
I know I have. I think eventually we'll see some commercially available sealed systems that use some liquid (probably not water because of its corrosive properties) and convection to move it around.
Something idiot proof and self contained with no mechanical parts, save perhaps a slower turning large fan to exhaust air.
So far existing heat pipes are not much more than a novelty. The wick style ones with alcohol as a fluid (mentioned here awhile back) look promising.
The giant skivved aluminum/copper blocks with the big ass fans aren't going to cut it, not just because of noise, but practicality.
I don't need no instructions to know how to rock!!!!
5 -- You just inherited $700 from your great-grandfather that's just waiting to be thrown out the proverbial case window
4 -- A loud smelly watercooling kit is the perfect complement to your neon light tubes
3 -- Why spend $200 for a brand new P4 when you can pay $500 for supplies and crank your P2 up 30 MHz?
2 -- That rock fountain you got for Christmas can be put to a much geekier use
1 -- To impress your classmates at Chubb Institute
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Alright - dude did this on a K6-2 450. They're about HOW many years old now?
I'd be much more interested to see him cooling an overclocked Athlon XP 2100+ with 1.9 vcore running at 2400 MHz - or something of the like - with the method in the article.
Ah well, I'm happy with my good 'ol pumps and radiator, myself.
You could just buy a *second* computer.
I'll form my OWN solar system! With blackjack! And hookers!
You may look here
:)
Without the need to implement that bulky bowl of water.
a beow...oh, forget it.
Seriously, the steam can condensate in pipes outside of PC and come back as a liquid. Just add a compressor and we've got a refrigerator. Can I keep my soda cool inside my PC?
Less is more !
What? You guys are still using water? I found The Ultimate Cooling Device: Hilary Rosen (aptly named The Ice Princess).
Just pay up and get the processor with the cache; It's much less than these wild overclocking schemes.
everytime there is a new inovation in cpu disign that reduces heat insted of just remaking a p4 to run cool enough to run without a fan, they crank up the clock so that its putting out even more heat then before, making water cooling required for a quiet system
I got it, but why can't a gas be used to cool a computer? True it's not as efficient as water, but it is safer from a safety standpoint.
I leave the sides off of my computer for better air flow and less dust collection, but mainly because I'm too lazy to put in case fans.
Since my case has to sit on top of my desk, this also gives me a little more space to put stuff (inside the case, out of the way of boards / wires etc).
What do I keep in there? First is the reciever for my wireless keyboard / mouse, the syncing cradle for my handspring visor edge, and a few important papers. Those are the things that don't really move.
The fun things in there are the mountain dew beer glass, the caffeine shot glass, and usually 2 - 3 open cans of dew. All have soda / caffeine in them and are actively used.
No, nothing has spilled yet, and yes, I do have cats. 3 of them. They know that if they go near the sacred tower, they get stuff thrown at them (usually a slipper, but on occasion a t-shirt if I find that first).
On a side note: I in no way have the balls to water-cool my case, other than replacing the cold soda every 30 minutes.
Work sucked, until it became unemployment, when it became slightly more tolerable. -Tet
And will this water-cooling pump disentgrate pthe cpu pump and leak water all over that nice chip?
Oh well. The chip was probably a DOritos..
Is that a 5 1/4 floppy drive in that machine? What's he running, a 486?
I read the internet for the articles.
This is what my next upgrade to cooling is, this sucks, literally
Funnel Pic
Well, gravity based home heating systems have been obsolete with the advent of the water pump? Why bother when it's well known that forced water flow will provide better thermal conductivity?
Your pizza just the way you ought to have it.
Imagine a beowulf cluster of these IN SOVIET RUSSIA.
Always good to see continuing advances being made in the field of compu-bong technology.
In Soviet Rush, today's Tom Sawyer gets high on you.
Chubb Institute.
That was great.
I think you meant to say 'better heat dissapation'? Thermal conductivity (of water) is fixed, based on the medium, as I recall.
I built a simpler cooler, able to dissipate the same heat flux of a normal heatsink."
So it works as well as a regular heatsink? whats the purpose then?
When do we see the first Lava Lamp mod?
Gas? Hey, that's a good idea, but we'll have to find a way to get it to flow across the chip, or better, mount a heatsink on the chip, then force some air across that sucker.
sorry, I wasn't listening
:)
By the way, typical bowls of water neither exhibit nor possess 'bulk'.
A bowl of water can, however, demonstrate: placidity; loneliness; readiness; refreshment; murkiness and of course, my favorite...non-distention pending external force or vibration. Bulk is for those things it takes a forklift to move, like my opinion
Thanks reminding me of fixing my grandparents PC.
The thing that should be pointed out is this is how liquid cooling should have been done from the start. The reason their not is because most if not all of the home pc case cooling systems are things slapped together by people without engineering background in such things. Good liquid cooling systems are designed like this. There should be no pump to cool your cpu. The problem is to do it right involves doing some calculations which most don't do so they just use a pump. It's not a very hard thing as you can see by the article.
Now on a side note, if you like the idea of passive cooling loops Shuttle XPC cases now come with them. They use very similar ideas. You have liquid in a tube, when it vaporizes it rises to the upper radiator where it condenses and a fan carries the heat away and the water returns to the cpu side of the loop. Not sure if it vaporizes or just gets hot to move up the tube, really just a matter of effectiveness. It does a good job in lowering cpu fan noise. Unfortenly the noise of the PSU is very high in these things, or at least my SN41g2, though i belive the P4's have same PSU. The need the same thing on the PSU as the cpu. Also the "heat pipe" is a work of art.
I forgot that water was so much more dangerous than nitrogen gas! Remind me to stay away from that glass of water next time I'm thirsty. (J/K, I understand your point). From a physical point of view, for equal volumes of gas and water, there will be many more particles in the _water_ phase. This will allow much more heat to be contained within the water phase, and the water should be a much better heat-absorbing substance than any gas.
Sure, heat convection flows, but your efficiency goes way up if you have an active flow. Same principle with hot water heating. They used to not have pumps to circulate the water - because it worked - but it's more efficient to have a pump.
And the department of redundancy department strikes again.
EveryDNS. Use it. It works.
AC's need not reply
...the motherboard manufacturers just don't put the processors on the back side of the motherboards.
Think about it. If the processor and other heat generating chips were on the reverse side you could mount the motherboard in such a way as to press against the large metal backside of your case cabinet. The case cabinet could be designed in such a way as to have indentations that force the processor flat against the case with heat sink gel. In fact the entire case back could be a water-cooled heat sink. This would keep the inside of the case "water-free".
Sure, this would take a radical new case design and motherboard (another industry standard), but that seems to be where we are headed right? I mean processors are getting hotter and Intel and AMD are trying to figure out what to do.
Why not?
BTW, I think it has something to do with the fact that the motherboard components are all wave soldered on one side. This would melt most plastic components on that side. I'm not sure about this.
I suggested awhile back. Might have to rearrange things a bit, but it's doable, and could even be stylish. No sense having the liquid that close, and one could cool some other items.
well many computer heat issues could be helped if both sides of the mobo was used.
Here fishie fishies
Hmm insteresting, I think I'll try adapting my old method of heating a room over to heating water. A cluster of overlocked chips might even replace my water heater...hmm...
vampirical
Water Cooled PCs? Try Notebook. Water cooled processor powered notebook has been on sale in Japan for almost a year by Hitachi. Whisper quiet operation. Running Pentium 4 2.2Ghz http://www.hitachi.co.jp/Prod/comp/OSD/pc/flora/pr od/note/flora270wnw4/index.html
Pics of the innards
http://ascii24.com/news/i/topi/article/2002/02/28/ images/images677847.jpg
On display
http://ascii24.com/news/i/keyp/article/2002/03/02/ images/images678064.jpg
A stirling engine has no moving parts? That's news to me. I followed your link to the sterling engine page and cliped the specs.
;-)
Specifications:
Height: 9.7" (24.6 cm.)
Diameter: 6.5" (16.5 cm.)
Weight: 1 lb. 3.3 oz. (547 g.)
Temperature differential required: 18 degrees F (10 degrees C).
Precision Ball Bearings: 4.
Piston Material: Graphite.
Power Cylinder Material: Borosilicate Glass.
Flywheel Material: Acrylic.
Metal Parts: Anodized Aluminum and Steel.
Rotational Speed: Approximately 150 rpm (speed depends on temperature differential, barometric pressure, and other factors) When running on your warm hand, the engine will run faster in cold rooms, slower in warm room, and not at all in very hot rooms.
I just don't get the 150 RPM and ball bearing portions of the specification if there are no moving parts.
On a serious note, the sterling engine requires a larger temprature diffrential than most people want to have with their cooling solution.
The truth shall set you free!
Nah... I'd use transformer oil, and I don't think a Lipton Cup-a-Soup would taste quite the same.
Transformer oil, however, is probably quite suitable for use in a CPU cooling system.
It has a higher breakdown voltage than air and is almost infinitely less conductive than real-world (ie. impure) water. Transformer oils are specifically designed for use as an insulating material in large power distribution transformers. Electric utility transformers at power substations, operating in the range of hundreds of thousands of volts, would arc between windings if the oil leaked out of them and air - with its lower breakdown voltage - seeped in. (Air breaks down at about 3kV per millimeter.) You can feel pretty confident that leaked oil won't short out IC pins on your motherboard. Hell, you could also ditch your power supply fan and fill that full of oil, too - just beware of relays and other mechanical components.
Heat transfer is a big reason for oil, too. In a car engine, much of the heat is generated by friction in the bearings, and motor oil pumped through the bearings takes that heat away. Transformer oil doesn't have to lubricate, nor does it have to carry away huge amounts of impurities or combustion by-products as in a car engine - the biggest requirements are heat carrying capability and high breakdown voltage. Large pole pigs (pole-mounted power transformers) are usually oil-filled and often have pipes coming from the bottom and going to the top - they serve as radiators. Oil flow is not by pump, the reliability would be too low - they're convective, too.
Finally, viscosity. Yes, this might be difficult, but transformer oils are available in a variety of thicknesses. You want a viscosity corresponding to SAE 0, which is the same as water. Even less might be available, though I've personally never seen it.
Density changes with temperature rise will have to be considered, since the lower density of hot liquids causes them to rise in the system (and is also the physics behind lava lamps). The system that guy designed is based on the density changes of water. Transformer oil won't behave the same way; accordingly, you'll have to whip out the old slide-rule and do some math. Calculus is your friend. Fortunately, the data on transformer oil should be readily available, it's an important design criteria.
Voltesso and Diala are good trade names which I've personally used in transformers loaded to hundreds of kilowatts at over 250,000V, at RF frequencies. (FAA obstruction lights on large VLF radio transmitting towers.) They're ALL PCB-free, and while you don't want to drink it, they're no more toxic than motor oil. And it takes a hell of a lot of work to make them catch fire.
In short, transformer oils are available in a variety of viscosities, are specifically engineered for their thermal transfer capabilities, are not electrically conductive, not dangerous, and are suitable for almost all of your electronic cooling needs.
The only problem I forsee is that you're gonna have a hard time buying them in quantities less than 45-gallon drums... though the drum would make a great passive radiator. Seriously, talk to a couple of linesmen with your local power utility, maybe you'll be able to talk your way into a couple of gallons of it.
And once that's done across all the machines in your compile farm, you can get to work tackling the big problems of why Linux isn't ready for the desktop yet.
Fire and Meat. Yummy.
Temperature is the average motion of molecules, not the number of molecules. Bearing away heat is really a matter of a temperature gradient. Different fluids have different heat transfer functions - it's true that it's typically higher for a liquid, but not always. So it's not just the number of molecules, it's the way they bump into each other, which is all about their structure. There are liquids which are very good insulators.
That was a very informative post, does anyone know if motor oil is conductive, I would think that a quart of 5W20 or another light oil would flow pretty well through a small submersable pump. My favorite transformer oil story was from a local Utility guy who came to our school years ago. He asked us if we ever wanted to shoot the transformers with our pellet guns, and then told us that he used to want to as a kid, but that it would be a bad idea since the oil would leak and the transformer would fail possibly explosivly.
What I found funny was that I don't think a single person had ever thought about shooting a transformer until he mentioned it, and the fact that they could explode might be something that would encourage young boys to shoot one with their pellet gun.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
It is about -12 deg outside at the moment. Why do this when I can just put my machine outside my window. You guys in California have to resort to something like this? Time to move....
Got Code?
A stirling engine has no moving parts? That's news to me. I followed your link to the sterling engine page and cliped the specs...... I just don't get the 150 RPM and ball bearing portions of the specification if there are no moving parts. ;-)
that's because that particular application of the stirling engine is trying to get mechanical energy out of it. (IANAME (mechanical engineer)) but as I understand it a pure stirling engine, essentially an external combustion engine, has no moving parts. Only the expansion and contraction of a gas medium inside the engine causes its motion. I'm not sure they would be any kind of solution because I think you would have to get the 'hot' end of the engine hotter than the cpu you are trying to cool, but then that may be an easier place to work with the thermal energy dissipation issues than the CPU itself. But if you are trying to use the engine for the purpose of thermal energy control, as this would be, the engine itself would have no moving parts.
the engines available at the link provided in the parent are pretty small, intended primarily for educational and entertainment purposes as opposed to real work, I just figured there are some links there to real information on how the stirling engine actually works. they are kind of intersting..taking a bit of time to get up to speed (perhaps another issue in their use for this particular application) but as I was saying they are supposed to be fairly efficient. I'm not sure how this is different than a peltier unit, though.
lots of free music downloads! earth2willi.com
I hope this can be implemented for modern PCs soon. the fans on modern PCs are the single most dangerously unreliable parts of the PC -- when it goes, the PC dies a slow and painful death. Not everyone has the know-how to clean these fans sporatically, and even among computer people, the knowlege to lubricate fans manually is a rarity. I'd really like to see systems like this, which rely on natural forces, and are less prone to mechanical failure, used instead of high-RPM dust magnets used in heatsinks today.
It's been a long time.
I saw one guy once using one of these to cook his lunch, using a pan in the water tank as a water bath to heat soup, and they can also get water to the boiling point to make tea. However, and computer system which gets water to the boiling point is not likely to be terribly effective (unless we go back to tube technology, of course)
Panurge has posted for the last time. Thanks for the positive moderations.
No, that's not what you did. The cooler you built was substantially more complex than a normal heatsink+fan. It was more expensive in materials, took more time for you to make, and required you to make more mods to your case.
It might have been quieter, though :-)
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journal
While probably not as high a dielectric as transformer oil, refrigeration oil is designed to have the coils of operating compressor motors submerged in it. There are three types of refrigeration oil- mineral, alkybenzene, and polyolester. All three are available in quarts and gallons in various weights. Mineral will be least expensive.
It may be a good idea to reduce the presure in the Water System to reduce the temperature to boil the Water. This may result in a much improved efficency if done the right way (The Steam has to go up from the top of the heatsink all the way to the top of the radiator, the Water has to be allowed to flow down from the bootom of the radiator to the bottom of the heatsink)
I guess Intel meant the surface of the Sun. This outer layer (photosphere) has a temperature of 6000C aprox. Yeah, it's damn hot but quite below from the 15000000C of the core (where the nuclear reactions take place).
:-)
Molten lava temperature is ~1000C so only 5000C to go
Why don't you just build a CPU that cannot heat up at all ?
Grear Idea eh?
I dunno, and even if someone did the motor oil they used would probably be different from yours.
So the best way is to check it yourself - stick a multimeter and measure the resistance. Given that most stuff on a motherboard is low voltage I wouldn't be overbothered by resistance-voltage properties of the oil.
simple multimeter tests don't just cut it, unless it can measure the 'hit through'(sorry, my english sucks and i don't know the proper word) capabilities of the substance.
water would make a fine insulator unless the 'hit through'(amount of voltage differential needed for the electricity to jump/hit like lighting through something) was small(and no, i'm not an electricity-engineer).
anyways, this kind of cooling has been done(submerging the whole mobo in something), couple of times. one guy used some biograde mineral oil succesfully.
theres at least one no-pump commercial solution too for liquid cooling, but it has a fan on the radiator.
though, in my opinion, getting rid of the pump doesn't bring you anything 'extra' since the pump makes next to zero noise, and noise damping the pump from environment is easy too. the real problem lies in how to get the water to keep cool without having extra fans(heatload on it gets quite big if you have cpu, gfx-card, chipset, psu, hd's and etc watercooled for silence). the bowl of that size that's in the article won't cut it.
and really, k6-2 could be cooled enough with just about any lump of metal compared to the 76w+ modern cpu's.
world was created 5 seconds before this post as it is.
Water is a very bad conductor of heat without good convection - you can boil water in the top half of a test tube while ice is happily sitting at the bottom - wrapped in gauze to make it sink, obviously.
When I am king, you will be first against the wall.
Why not take in one step further and install a CPU-powered lava lamp? It's the next logical step from AOpen's valve amplifier motherboards.
I remember posting in a car forum after doing some research. Oils are very BAD.
.6W/mK (bout halfway down the page) .13W/mK.
Thermal contuctivity for water is
The oil I found was from some company called Slovnaft out of Slovakia (the only one I could find that would provide details). But their oil that is specifically meant for moving heat has a thermal conductivity of
Another thing I might point out is if youve ever got motor oil on your hands youll notice it feels warmer than water of the same temperature. It doesnt carry heat away like water will.
Alas, Olive Oil burns less calories ;)
pi = 3.14
Oh, thanks for clearing that up. Didn't they rule that pi=3?
Ed Wedig
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Unless you're dealing with things in the kilovolt range, you won't be reaching the field strength needed for breakdown of the material. (I can't remember the exact term, it's not "hit-through", and it's not "breakdown voltage" either since what matters is the field strength (in volts/meter) rather than the pure voltage.
The problem with water is that even small amounts of impurities cause it to conduct. Pure water has a pretty low conductivity and a high breakdown field strength, but even a tiny amount of impurities will change that.
MOST if not all oils you're likely to use in a computer are going to have much higher breakdown potentials than air. What matters is whether they're conductive or not (Most aren't)
If you use motor oil, two things:
a) Get the lowest weight possible.
b) Don't get a multigrade oil. (Denoted in the form nW-m, for example 10W-40) These oils are designed to increase their viscosity as temperature increases. (To provide good protection at high temperatures while not being total sludge that prevents an engine from moving at low temps)
retrorocket.o not found, launch anyway?
water cooled power supply
Water Cooling Made Easy
Some water cooled case
A guide to water cooling
Yrt another DIY Guide
On OTS water cooled...
Another water cooled Power Supply
Fish tanks says it all...
Another water cooled story..
When physicists do water cooling...
Hmmm let me guess... another water cooled story
The original?
Doesn't this strike everyone as pointless?
The term you are looking for is the electrical breakdown voltage. Oils for transformers are off in the multi-KV range.
See my journal, I write things there
if youve ever got motor oil on your hands youll notice it feels warmer than water of the same temperature. It doesnt carry heat away like water will.
:-)
True, but water is about a zillion times more evaporative than oil, so if you get any water on you, especially if it's warmer than body temp, it's already evaporating and thus feels cooler than warm oil would.
If you have ever got your hands wet in the winter time, you'll notice that it literally sucks the heat right out of your hand because the relative humidity in winter is usually very low and it doesn't take much to make the water on your hands start evaporating. If you got cold oil on your hands (at the same temperature as the cold water) it won't feel nearly as cold as it's not evaporating. It will pull enough heat out of your hands to reach thermal equilibrium and then stop.
If you have ever splashed hot water on yourself, you'll notice that even if you get burned, the inital 'hot' part of it is over with almost immediately. Hot oil on the other continues to feel hot and will continue to burn you much longer.
In an enclosed system where there is no evaporation, the difference won't be nearly as great.
Has anyone ever built a water-cooled PC that uses an external fountain as a radiator? Obviously you would want it far enough away from the PC so as to prevent splashing, but I think one of those little zen rock fountains would make an interesting and relaxing radiator, as long as you remembered to keep adding water...
A computer once beat me at chess, but it was no match for me at kick boxing -- Emo Phillips
Nah... I'd use transformer oil, and I don't think a Lipton Cup-a-Soup would taste quite the same.
Transformer oil, however, is probably quite suitable for use in a CPU cooling system.
I've been considering just dipping the whole computer in a vat of oil. Should work fine (at least for awhile). Of course the disk drives would be external to the vat. Now if I could just get 10 or 15 litres of fluorinert (sp?) - that would be very cool (pun not really intended). Dead silence in the computer room. Wow.
90% of the wealth is in 2% of the pockets. Bummer to be in the majority.
Water (even distilled) is probably bad news if it comes in contact with active powered-on circuitry. Enough stuff will dissolve in the water on contact to make it conduct.
Powered-off circuitry is a different story. Salt water will corrode anything FAST. (This is why designing marine electronics is such a pain.) Tap water and distilled water won't corrode stuff nearly as fast - i.e. the occasional soaking followed by a good drying-off won't damage the equipment at all.
I've heard that this was used sometimes in the Navy - If a piece of equipment was accidentally splashed on by salt water, they'd take it into the showers (Not distilled, but much fresher than seawater) to rinse out the corrosive saltwater and then put it into a warm dry place to dry out.
retrorocket.o not found, launch anyway?
I built a simpler cooler, able to dissipate the same heat flux of a normal heatsink."
So you built something more complex than something simple and it only works as well as the simple item? I hardly say that is worth mentioning.
Stay in the shallow end.
"Times may change, but standards must remain the same." - George Carlin.
A few years ago, Jon "Maddog" Hall was speaking at Cornell. The local LUG treated him to lunch before his presentation, and he told us about a phase-change convective heating attempt Digital once tried. It was to cool a CPU that was half CMOS half ECL. (ECL is VERY fast logic, but it's known for being a horrendous power hog, far worse than even TTL).
The problem was that the system would promptly stop working and the CPU would melt if it were tilted too far.
As to heat pipes - They are FAR more than a novelty. Look at Shuttle's small form factor systems. If you consider those to be a novelty, look at any recent Dell laptop. I know for a fact that the Inspiron 8x00 (8000,8100,8200) series use heatpipes for cooling the CPU. These use wicks and hence function even when the heat source is above the radiator.
retrorocket.o not found, launch anyway?
The longer a heat pipe is, the less efficient it is and it only moves heat, so you still need somewhere to dump it, whether convection, conduction or radiation.
See my journal, I write things there
This discussion is an interesting parallel to a letter that appeared in last month's Cycle World magazine about air vs. liquid cooling in motorcycles.
The main advantage put forth for liquid cooling over air cooling in motorcycles is the ability to route the cooling water directly to the components that need it most rather than hoping that some of the fast-moving air makes it to the cooling fins of an air-cooled machine. The situation in CPUs is arguably worse because you have to artificially generate the fast-moving air that is readily available in a moving vehicle.
It seems to me that by building water jackets for CPUs you are already missing out on a great deal of theoretical efficiency available from water cooling, which would be to design the chip with cooling passages built in. Most of the projects I have seen are pretty similar to this - low budget efforts that obviously wouldn't take chip design into account.
I did a brief search and wasn't able to find much beyond these types of projects. Does anyone know details about projects out there that involve liquid cooling from the start?
Have you seen my stapler?
Damn it, now we are restricting our computing to Earth's (or other planets' surfaces). Convective cooling doesn't work without gravity.
Galium Arsenide is the material of the future, and always will be.
You may also want to try mineral oil. I have it running in my rig and it works pretty well. Its a bit easier to come by, as you can get it at your local big-name farm supply store. Only problem is that, being oil, once it gets on something its really hard to clean off.
"A coward dies a thousand deaths, the brave but one."
A less hard-core alternative would be mineral oil. Cheap, easy to get in smallish quantities, and I've seen it used in this way (on slashdot, even.)
It doesn't have the same properties as transfomer oils, but they may not be obtainable.
What a waste, people need to conserve water. They should be using urine instead of water.
someday we might have the CPU mounted at the bottom of our case, and have a cool lava-lamp looking effect running up the side wall
This indeed does sound like quite and awesome idea for a case mod. The only problem I see is that on my lava lamp... the glass itself gets hot - so what's the actual internal temperature of the lamp fluid (does it draw off enough heat or just retain it?)
It has indeed been done (sort of) ...
http://www.overclockers.com/tips699/index.asp
Maybe I'm crazy but if your processor is vaporizing water doesn't that mean that its running at 100 deg celcius?
Isn't that a slightly less desireable temperature for your CPU to run at?
Yeah, Transformer Oil! Make sure you get the stuff with PCPs.
Cool! I was thinking of using one of those little desktop ones, but this guy went one step further!
A computer once beat me at chess, but it was no match for me at kick boxing -- Emo Phillips
The picture shown indicates the cold-input pipe is almost at the same level as the hot-output pipe.
I would tend to believe the flow past the CPU could be improved simply by making the cold-input pipe longer, making it loop down a bit lower before connecting to the CPU hat. This might produce a slight boost in gravity/convection.
A piece of insulation between the tubes would eliminate any pre-heating of the input water, as well, if the selected tubes are not good insulators.
Jamie.
Transformer oil is a powerful cancer agent. Be careful to NOT touch or smell too much of it.
Seem to recall that Shuttle uses convective cooling in their mini system's heatsinks... i'd have to check though.
You can try wiping that card down with a moist paper towel. More than likely the mineral salts in the mouse urine is shorting out the card. Unless you have a very cheap card, the mineral salts should be strictly on the surface.
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Im sure both answers are right. I only say this from removing my engine in cold weather. Of course you have to drain all the coolant and motor oil. Youre obviously right about the humidity levels affecting it.
The hot fluid splashing on you was one I was going to use. I was going to say that the oil likely burns longer because it insulated much better.
The only instance that I could think of that would be a more closed system (albeit not very scientific) would be to have bucket of cold water and cold oil. Stick your hand in and learn. I dont have that much old motor oil around so count me out.