Comment Different liquid for cooling (Score 4) 319
There are a couple of liquids which you might consider for your cooling to avoid the liquid problems. The one I would look strongly at is acetone.
Yes, the stuff smells bad, but it will remain as a liquid (and not get gooey or gelataneous) down much colder than -30 or -40 C... I use dry ice/acetone baths all the time, and it's still very much a liquid at -70C.
It's immiscible with water, so you won't have any water-contamination problems, and any water that hits the cold acetone will instantly freeze.
Although it has a relatively high vapor pressure at room temperature (i.e. it smells bad) the vapor pressure isn't nearly as bad at cold temperatures, and you won't smell it at all. And you won't smell it anyway if you have a cover on the case.
So anyway, you have my vote to use acetone as your cooling fluid.
Yes, the stuff smells bad, but it will remain as a liquid (and not get gooey or gelataneous) down much colder than -30 or -40 C... I use dry ice/acetone baths all the time, and it's still very much a liquid at -70C.
It's immiscible with water, so you won't have any water-contamination problems, and any water that hits the cold acetone will instantly freeze.
Although it has a relatively high vapor pressure at room temperature (i.e. it smells bad) the vapor pressure isn't nearly as bad at cold temperatures, and you won't smell it at all. And you won't smell it anyway if you have a cover on the case.
So anyway, you have my vote to use acetone as your cooling fluid.
