direct cooling of electrical components
direct cooling of electrical components
(OP)
Hey all, I need some advice. I am trying to cool electrical devices, i.e. PCB's and IC's, by directly immersing in a liquid coolant. So far I have come up with a quite a few options, with these on the top of the list: an alcohol, mineral or similar oil, or something that is meant to be used for this purpose. The problem with the latter is the price. What I have found from Dow is $1200 for 55 gal. drums of the cheapest fluid, I need 2 gallons. Does anyone have a suggestion for a dielectric non-corrosive fluid to operate in the range of -20C to 25C with decent heat transfer properties and relatively low (<100cP) viscosity? Or does anyone have suggestions on where I can find some Syltherm (or similar HTF) in small quantities? Thanks.





RE: direct cooling of electrical components
Try a Liquid Gas like CO2 or Liquid Nitrogen, the are non-conductive. Dry ice in alcohol or other non-conductive liquid may work, too.
RE: direct cooling of electrical components
RE: direct cooling of electrical components
Beside this I can not recommend the deionized water. Deionized water tends to be very corrosive and can only be used if some additive to control this is used, Unfortunately this increases conductivity...
Maybe you should consider an alternative solution: Design your PCB using surface-mount devices, lots of vias to transfer the heat to the bottomside, an a liquid-cooled heatsink.
The German PCB-manufacturer ILFA did some resarch on water-cooled PCBs, called ILFAcool. Visit http://www.ilfa.de for more information.
RE: direct cooling of electrical components
How about alcohol? Does any one have any experience with it or just an opinion? I am concerned with volatility, but between -25 - 25C, I don't think it should be a problem. Does it interact with plastic? Someone suggested acetone, but I think that would degrade components faster than oil, or just outright dissolve them. I have seen it used as a coolant in specifics apps though.
I found a five gal. jug of syltherm XLT for $350, which is still pricey, but within reason. Ethanol with the necessary purity is around the same price, but available in the exact quantities I need. Isopropyl and methanol would work too, and they are much cheaper. So right now, it's between those four. Any thoughts?
RE: direct cooling of electrical components
RE: direct cooling of electrical components
phase change material ( see www.climator.com )
Alcohol adsorbs H2O.
Liquid compatible with all plastic is hard to find...
<nbucska@pcperipherals.com>
RE: direct cooling of electrical components
RE: direct cooling of electrical components
can you give the power density which has to be removed from your board ?
This would be helpful to steer further discussions in the right direction.
RE: direct cooling of electrical components
The problem is that there are several compact sources of heat, 4 at 20+W/cm^2, roughly 6 cm^2 apiece, ~500W total. We have looked at heat pipes to spread that out a little too. Several other (10) sources produce ~5W/cm^2, and those total roughly 60cm^2. These lower output components could be actively air cooled, but I think it is really asking to much to air cool the whole thing. This is where the liquid cooling comes in. When it's all said and done, I need to remove ~800W total from 2130cm^2 total board area (9000cm^3 volume, 30cm x 20cm x 15cm). There are multiple boards, so each would require it's own cold plate or heatsink, and with the limited space, it will be hard to get them in. The 4 100+W sources are the real concern, but I would like to keep the whole thing as cool as possible, so I thought that it might be easier, not to mention just better overall, to use immersion cooling rather than cold plates. Another app we have right now is using 2 liquid cooled heatsinks on 2 150W sources, which works fine. Some of the ~5W/cm^2 components are a little hotter than they could be, but within specs.
Indirect liquid cooling is not unfamiliar territory and would likely work fine for this too if we can cram it in, but immersion seemed to be ideal. Lack of knowledge about immersion is why I'm here though. Should we hold off on direct liquid cooling except as a last resort? Is it that much more expensive/difficult? I thought it might save some time and agony to try it first, and if it worked, great.
RE: direct cooling of electrical components
RE: direct cooling of electrical components
RE: direct cooling of electrical components