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Topic: Heat transfer of metallic solutions  (Read 5062 times)

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Offline rabidgnome229

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Heat transfer of metallic solutions
« on: March 02, 2006, 07:19:22 PM »
A little background may help before I get to my question ;D
I have a custom built PC with a watercooling system.  The system works by situating a copper waterblock on top of the processor.  Water flows through the waterblock and absorbs the heat that the processor creates.  The water then flows into a radiator which releases the heat into the air.
One drawback of water is that it isn't terribly efficient at absorbing and releasing heat.  So my question is, since metals transfer heat much better that water does, would a solution containing metal ions (probably gold or copper nitrate, or something similar) be better and conducting heat?  I have asked on my overclocking forum, but between a few dozen responders nobody could figure out what a solution is ::)
Everybody in the PC world is constatly looking for a better way to cool their computer, so any help will be greatly appreciated, and not just by me :D

Offline mike

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Re:Heat transfer of metallic solutions
« Reply #1 on: March 02, 2006, 07:36:20 PM »
I am not entirely sure but I doubt it would make much difference. The properties of the metal salt would be different from the properties of the elemental metal (example copper (Cu) metal is different to copper ions (Cu2+)) I would presume that there would be more disadvantages than advantages to adding salts to the water, for example salts will precipitate out and cause blockages etc. I would think that changing the amount of surface area of the water would probably help more, so some re-engineering of the block may help. Intersting topic though, wish I could be of more help :)
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Offline Juan R.

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Re:Heat transfer of metallic solutions
« Reply #2 on: March 04, 2006, 01:07:05 PM »
What cool query! I was an overcloker in the recent pass (prehistory in computer time) with a computer done by me!! I was able to obtain 1300 for a AMD 1000 on a nice Asus using a special air conduct (an external direct pipe to processor with two fans on sides which obligated to re-site the source power in the case, etc, etc.) designed by me and helped by my young brother -who did many contributions- on a Volcano system, when then the record was near 1500 for the AMD 1000. I had problems with memory modules -one crash |:(-. I would import expensive specialized overcloker tested memory modules for continuing forcing it to 1400 or so, and then i decided to stop to play. I know noting about modern state of art and records :-)

So my question is, since metals transfer heat much better that water does, would a solution containing metal ions (probably gold or copper nitrate, or something similar) be better and conducting heat?

First about heat transfer mechanisms. There are three: radiative, contact, and convective.

Solid cooper has an excellent thermal conductivity because is a solid metal. All solid metals are good contact conductors, because the electronic cloud of their atomic structure. Mike is correctly right here. If you use a solution if ions of Cu, your main thermal mechanisms will be convective which is dependant of size and movility of ions and is not so efficient as via contact. I have no data but i would wait no real improvance here by use of ions (i suspect).

Try to calculate by yourself! Take the molar conductivities Lambda for chemicals that you want use, compute the total conductivity, and compare with water

Units = W/ (K m)

Lambda water = 0.6062

Lambda air = 0.0262.

Lambda (solution of I) = Lambda-per-I * (concentration-of-I)
+ Lambda-per-water * (concentration-water)

Units of concentration you amy use are dependant of units used for Lambda-per-specie: molar, massic, etc.

Remember to compute for all ions on solution, that is if there is Cu2+ you may sum also for the corresponding anion generated in the neutral solution.

If Lambda-per-I for your ion I is bigger that for water, then increasing concentration of I you are increasing total conductivity of your solution, but there is a limit: ionic solubility. Beyond that limit, you obtain salt precipitation as Mike said.

I suspect that water is directly contacting with the Coooper waterblock. Right? Then remember that introducing ions in the solution your are increasing electric conductivity in the solution and this would make damage in the computer. This is reason that some water-coolings guys prefer to use deionized water in the circuit. That is, water with no ions (well, still there is a few there). But then one obtains corrosion... Last i know about these topics is the use of "water wetter". Search in google about it.

Options if watter wetter does not work for you needs? A lot of

Re-desing water circuit. But this is also limited by surface of the chip, that is it is.

Substitute passive dissipation in the external radiator by forced one external via pumps air. This is cars enginering!

More radical, use mineral oil and a completely different desing as here I do not know improvements of that and may offer problems with oil.

In the past some people try to use a refrigerator for cooling instead of a tank as above!

But remember that after of all dissipated air is the mixture of static requirements X dinamic requirements. Yes, Lambda water is 23 times Lambda air but if you increase 23 times the flow of air... This review claims water-colling performance for the new Volcano 7+.

I suspect that improvement in future coolers will be by the use of some special material. Chemists have desiged special nanomaterials (e.g. Carbon nanotubes) with better thermal conductivity (x3) than Cu or any other metal available in nature. It is now expensive, but probably we will a new generation of dissipators without Cu in future.

Apparently, this industry is ready to comercialize an improved graphite/Cu material (x2) for cooling electronics.
« Last Edit: March 04, 2006, 01:47:31 PM by Juan R. »
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edanru

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Re:Heat transfer of metallic solutions
« Reply #3 on: March 26, 2006, 09:45:46 AM »
Just put green cooling water in the system.
like the water you buy for your car radiator.
they can absorb more heat then regeular one.

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