Re:Ways to think about water (2015)
by billfruit on Tuesday September 21, 2021 @10:45AM
(#28605537)
What about atmospheric water extraction/harvesting? Is it a viable alternative with current technology?
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Re:Ways to think about water (2015)
by tsimionescu on Tuesday September 21, 2021 @11:21AM
(#28605925)
Not really, since water vapor must eliminate huge amounts of energy to turn back into liquid water - each kg of water vapor will dissipate 2.27MJ to turn into a kg of water at 100C. Since this is a thermodynamic limit, there's no enginerring around it.
Ostensibly, heat pumps could dual-purpose as AC and dehumidification, but if you have enough water for a heat pump, the condensation you collect probably isn't going to be very significant.
Edit: My point being you don't have to supply 2MJ of energy, you need to move it. That can be done for less.
Re:Ways to think about water (2015)
by tsimionescu on Tuesday September 21, 2021 @04:11PM
(#28609359)
> My point being you don't have to supply 2MJ of energy, you need to move it. That can be done for less.
Understood, but the point is still that you need to keep something cold enough for vapor to condense, while the condensation of 1 kg of water is dissipating enough heat to bring 5.4 kg of water from 0 to 100C. Even if just moving the heat around, there's just too much of it.