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Q & A: liquid air engine

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Most recent answer: 01/01/2008
Q:
Is it economically feasible to use liqufied air as the potential source of energy to drive a piston or turbine engine? Would the energy out be greater than the energy required to make the liquid air?
- Jeff (age 25)
NY
A:

Most importantly, under all circumstances the work required to liquify the air will always be more than the work obtained from the engine. That's a direct inescapable consequence of the laws of thermodynamics.

So the question of whether such an engine would be economical depends on the efficiencies of the liquifier and engine, as well as the costs of maintaining the thermally insulated liquid. I can't think of any major application for which it would be economical.

Still, it's fun to drive a little liquid air engine as a demonstration in lecture.

Mike W.

(published on 01/01/2008)

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