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Michael Noonan
2007-Sep-26, 09:31 PM
Has there been any research on using the heat and cold of space to do the scrubbing of carbon dioxide?

Since CO2 becomes a liquid before either oxygen or nitrogen couldn't the air be pumped to the cold side and when the CO2 becomes a liquid syphon it off.

The CO2 free air then pumped to the warm side for reheating and reintroduced. Then less plants could be used to give the air that fresh smell and the concentrated CO2 might be more efficiently converted back to carbon and oxygen if plants are more efficient in a richer CO2 atmosphere.

It means two gardens but that gives more choice to the crops that could be used in space and a mechanical separating method should either garden fail.

Jason Thompson
2007-Sep-26, 09:45 PM
1: carbon dioxide doesn't liquify, it simply goes solid.

2: Which is 'the cold side' and is it cold enough? The spacecraft will always be radiating heat from itself and its electronics. I doubt any part of the spacecraft gets cold enough to liquify the components of air. Far easier just to bung in a load of lithium hydroxide canisters.

hhEb09'1
2007-Sep-26, 10:18 PM
1: carbon dioxide doesn't liquify, it simply goes solid.Compress it a few atm, then it would. Compress it a lot, and it would liquify at room temperature.

neilzero
2007-Sep-26, 11:21 PM
Hi Michael: That should work if the air is pressurized to about 100 psi. Pressurizing will heat the air. Outside will cool the air, so the carbon dioxide liquifies. Since there is about 1000 times more air than carbon dioxide, a lot of energy is used to compress all that air.

Michael Noonan
2007-Sep-27, 04:14 AM
Hi Michael: That should work if the air is pressurized to about 100 psi. Pressurizing will heat the air. Outside will cool the air, so the carbon dioxide liquifies. Since there is about 1000 times more air than carbon dioxide, a lot of energy is used to compress all that air.

Thank you,

Space is one of those things that throws up a lot of very interesting challenges. :)