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Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hey guys
I'm contemplating to use ethanol as a direct cooling agent for power electronics, and information for this use is hard to find. DOs anyone know what would be approximate conductivities (compared to, for example, deionized water) of 96% and 99% dehydrated ethanol, for voltages <500V?
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
It will be a better insulator than high purity water. but it will have a lower heat capacity and lower boiling point. It also tends to attack some insulators and above all, it's very flammable.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi bored chemist
if 96% ethanol can attain better insulating properties than deionized water, that's excellent news.
Heat capacity is around 2/3 that of water if I remember correctly, not a big deal here.
As far as flammability goes I'll have to deal with it; the system will not be exposed to air but I'll have to take special care preventing possible large semiconductor explosions resulting in loss of containment and burning alcohol spilling everywhere.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hello
Well, a part of the idea is to be able to cool the alcohol down to about 170 kelvins in order to enhance conductivity of the mosfets. Alcohol is the cheapest and most available substance with decently low freezing point. Volume is going to be likely less than 1 liter.
For room temperature, I could use oil or fluorinert, but neither are too easily available here nor cheap.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Hi, Wish I'd read this about a week ago before my expensive BRD write diode bit the dust from overheating. Turns out that the laser emitter gets ridiculously hot despite the surrounding can getting only warm.
Direct liquid cooling would have the advantage that the diode would have a better optical match between the output facet than facet--air. It shouldn't affect the cavity itself as this is sealed.
(might try it with a sacrificial writer diode from a DVD..)
I know this is a late reyply, but ethanol cooled to 170 K or -100C is solid. Acetone and dry ice is a common cooling mixture. Anyhow most solvents coolrd below -20C would be below their flash point, and therefore not possible to ignite. A dirty solution is to use propane tanks, and use evaporative cooling. But the vapour must be burned of safe,y or you will create an explosive gas mixture.
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Conductivity of ethanol at various concentrations
