Sciencemadness Discussion Board

CO2/ LN2 alternative cooling baths

symboom - 2-8-2017 at 05:05

Has anyone used this for cooling I found that a concetrated calcium chloride solution can be frozen solid with canned air
I have been researching alternative cooling baths using canned air a mixture of dry ice and canned air which may drop the temperature lower than the famous dryice acetone bath

The benefit to canned air is it is not very flammable

1,1-Difluoroethane
Canned air
−25 °C Boiling point
Instantly freezes water and boils away


1,1,1,2-tetrafluoroethane
134a automotive freon
−26.3 °C boiling point
Could also be used

And if your lucky to find
1,1,1-Trifluoroethane, in canned air
−47.6 °C lower than propane


Both flammable but extremely cold
Butane -1°C boiling point
Havent see much

Propane -42°C
And liquid propane is compressed more

Dry ice
From supermarket

Airsoft large CO2 tanks
Or dry ice from CO2 tanks
https://m.youtube.com/watch?v=L7U2CbxfMMk

Dry ice from fire extinguisher
https://m.youtube.com/watch?v=tLNHDxd6nDc


https://en.m.wikipedia.org/wiki/List_of_cooling_baths

I guess test to see it it will freeze
acetone
Ethanol
Methanol


[Edited on 2-8-2017 by symboom]

[Edited on 2-8-2017 by symboom]

Melgar - 2-8-2017 at 13:24

You can tell how cold those fluids can get things by just looking up their boiling points. 1,1-Difluoroethane has a boiling point of -25˚C, so that checks out.

CO2 sublimes at -78˚C, but it needs a liquid to dissolve in in order to use it for a bath. Any substance that's a liquid at that temperature and will dissolve CO2 could work, acetone tends to be use because it's cheap and widely available.


symboom - 2-8-2017 at 14:05

Thanks for that I was thinking that it had to do with the boiling point but I was not sure putting any of these even dry ice under reduced pressure an vacuum would be the only way to achieve colder temperatures it seems

Putting liquid propane in a vacuum would drop the temperature
But I dont know how low

https://www.google.com/patents/US5787716
Dry ice in a vacuum
-54C
Probally not practical by liquid CO2 then pull a vacuum should drop the temperature lower




[Edited on 2-8-2017 by symboom]

XeonTheMGPony - 2-8-2017 at 17:57

diflouroethane burns quite well in liquid state fiy

Melgar - 3-8-2017 at 09:49

The reason for the discrepancy with CO2 is that it requires more thermal energy to transition from solid to gas than from liquid to gas, and it's never a liquid by itself at atmospheric pressure. The only way to get it in a liquid phase at atmospheric pressure is by dissolving it in some other liquid.

[Edited on 8/3/17 by Melgar]