Conductivity of ethanol at various concentrations
Marko, Thu Nov 15 2012, 09:24PMHey 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?
Marko
Re: Conductivity of ethanol at various concentrations
Bored Chemist, Thu Nov 15 2012, 09:30PM
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.
Bored Chemist, Thu Nov 15 2012, 09:30PM
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.
Re: Conductivity of ethanol at various concentrations
Marko, Thu Nov 15 2012, 10:01PM
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.
The insulators used will involve:
- PCB material (fiberglass + epoxy)
- Acrylic
- PVC
- Latex rubber seals
As far as I can tell there should be no problems with those, but I'm always glad to hear expert opinion :)
Marko
Marko, Thu Nov 15 2012, 10:01PM
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.
The insulators used will involve:
- PCB material (fiberglass + epoxy)
- Acrylic
- PVC
- Latex rubber seals
As far as I can tell there should be no problems with those, but I'm always glad to hear expert opinion :)
Marko
Re: Conductivity of ethanol at various concentrations
Pinky's Brain, Thu Nov 15 2012, 11:42PM
Why use it over oil?
BTW, how much volume do you have to fill? There is always Freon 11 and Fluorinert.
Pinky's Brain, Thu Nov 15 2012, 11:42PM
Why use it over oil?
BTW, how much volume do you have to fill? There is always Freon 11 and Fluorinert.
Re: Conductivity of ethanol at various concentrations
Marko, Fri Nov 16 2012, 01:33AM
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.
Marko
Marko, Fri Nov 16 2012, 01:33AM
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.
Marko
Re: Conductivity of ethanol at various concentrations
Conundrum, Fri Nov 16 2012, 06:58PM
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..)
Conundrum, Fri Nov 16 2012, 06:58PM
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..)
Re: Conductivity of ethanol at various concentrations
rikkitikkitavi, Fri May 06 2016, 07:45PM
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.
Acetone and dry ice is probably a safe bet.
rikkitikkitavi, Fri May 06 2016, 07:45PM
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.
Acetone and dry ice is probably a safe bet.
Re: Conductivity of ethanol at various concentrations
Bored Chemist, Sat May 07 2016, 05:51PM
Bored Chemist, Sat May 07 2016, 05:51PM
rikkitikkitavi wrote ...
I know this is a late reyply, but ethanol cooled to 170 K or -100C is solid.
No it isn'tI know this is a late reyply, but ethanol cooled to 170 K or -100C is solid.
Re: Conductivity of ethanol at various concentrations
rikkitikkitavi, Sat May 07 2016, 06:21PM
With a viscosity around 10 mPas it might aswell be for the purpose of convective cooling.
rikkitikkitavi, Sat May 07 2016, 06:21PM
With a viscosity around 10 mPas it might aswell be for the purpose of convective cooling.
Re: Conductivity of ethanol at various concentrations
Bored Chemist, Wed May 11 2016, 03:00PM
Good point; a lot of liquids will be rather viscous at those temperatures.
Bored Chemist, Wed May 11 2016, 03:00PM
Good point; a lot of liquids will be rather viscous at those temperatures.
Re: Conductivity of ethanol at various concentrations
Proud Mary, Fri May 13 2016, 06:53PM
Proud Mary, Fri May 13 2016, 06:53PM
Re: Conductivity of ethanol at various concentrations
Enceladus, Thu Feb 09 2017, 03:19AM
Difluoroethane computer duster is a decent and fairly cheap (2-$3/10oz) refrigerant that is readily available, easier to liquefy than propane (vapor pressure: 5.1 Bar @ 20 C), an excellent dielectric, remains liquid down to 156K, has low toxicity, low viscosity, and is not readily flammable. It is combustible if subjected directly to a flame however and releases toxic and corrosive gasses when burned.
Enceladus, Thu Feb 09 2017, 03:19AM
Difluoroethane computer duster is a decent and fairly cheap (2-$3/10oz) refrigerant that is readily available, easier to liquefy than propane (vapor pressure: 5.1 Bar @ 20 C), an excellent dielectric, remains liquid down to 156K, has low toxicity, low viscosity, and is not readily flammable. It is combustible if subjected directly to a flame however and releases toxic and corrosive gasses when burned.
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