Dry ice question

[ctgilles]

Hey guys,

Since I'm gonna bench soon, I have a little question: with dry ice, I'm gonna use 50% antifreeze and 50% water, will this be the right mixture so I can still pump it around in my circuit? Or do I need pure antifreeze? (remember the viscosity guys :D )

[CodeRed]

I am no expert on this so take what I say with a grain of salt.

I think dry ice is too cold (-78 deg C) for the antifreeze/water combo to work. Antifreeze is only good for about -20 to -40 deg C (depending on brand). I heard people using acetone as the cooling fluid to use with dry ice as it doesnt freeze at -78 deg C.

[Charles Wirth]

Dry Ice will freeze Antifreeze if you mix too much water

[aenigma]

Well antifreeze will go down to about -40c or so if you mix it correctly.Use alcohol, much better liquid to use...

[ctgilles]

alcohol, methanol, I got that :D

[KnightElite]

Methanol is good, if you could get denatured ethanol it would be better though, since it's not toxic, unless your drink it, and according to this (http://scifun.chem.wisc.edu/chemweek/ethanol/ethanol.html) it freezes at -114.1ºC. It's a few dollars for a bigass bottle of the stuff too, from laboratory equipment companies. And actually, that's a better freezing point than methanol, which is only -98ºC.

[aenigma]

Methanol has better heat transfer abilities though.It is toxic, but just don't drink it.I got a mouth full of it(priming a pump) and I didn't even get sick.But I also didn't swallow it :)
If your going to just throw dry ice in the methanol, then your going to be breathing alot of methanol vapors.You should make a heat exchaner.Just a spiraled copper pipe in an ice chest or something insulated.Pour the dryice over the pipe...

[ctgilles]

Yeah, my mom has a pharmacy, so getting some methanol won't be difficult :D

Thanks guys!

[Tedinde]

I've used 25% antifreeze, 75% water with no problem. using a danner mag drive model 7, really high flow i think was the key to it not all freezing. With 10lbs of dry ice in a 5 gallon bucket. 1/3 of it froze on the bottom. But it ran till everything melted. no problems.

Hoses got rock hard though, watch that and possible leaks. It was feeding my swiftec will 226 watt TEC, which probably warmed it up quite a bit, but with no TEC you'll probably freeze my above Ratio.

The dry ice over the pipe is better, you waste a lot just dropping it in water, and the fog!!!