In another question: How does the freon compressor work at 0 gravity? This seems overly complicated to get some cold air in space.

Can an A/C compressor (we use in our house) be made to have gravity by spinning duel compressors in a centrifuge to keep the oil at the bottom of the compressor and work?

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  • $\begingroup$ Most important question first: where do you put the waste heat? You can't just vent it outside. You need a radiator and most likely a second cooling circuit to accommodate the different pressure and temperature regions. $\endgroup$
    – asdfex
    Jul 29, 2018 at 18:31
  • $\begingroup$ Cooling the atmosphere within the Apollo CM was possible and was done successfully. The LM needed cooling too, in zero gravity as well as on the moon. $\endgroup$
    – Uwe
    Jul 29, 2018 at 22:21

1 Answer 1


The compressor isn't the only part that relies on gravity.

  • In the evaporator, the refrigerant boils, and you have to separate the gas from the liquid. That's also a process that relies on gravity: in gravity, the gas rises to the top. In 0 G, gas and liquid remain mixed.
  • the system diagram you show is for cooling the air. The freon system in the Shuttle looks more complicated because the freon has to be piped to each system that must be cooled. In 0 G, air convection (=hot air rises) doesn't work, so passive air cooling doesn't work. You have to remove the heat using other means. You could use fans to move the air, but then you'd have to run air ducts everywhere. A freon loop is simpler (and quieter).
  • $\begingroup$ so all if all those parts could rotate then yes? Would it expend less electricity or more? $\endgroup$
    – Muze
    Jul 29, 2018 at 20:27
  • $\begingroup$ @Muze it somewhat depends on how much rotation you apply, but since rotation results in acceleration and gravity results in acceleration as well, yes, it would work. You'd most likely have to rotate the entire spacecraft though. $\endgroup$
    – DaGroove
    Jul 30, 2018 at 9:59

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