Quote:
Originally Posted by drmiller100
I'm not following the disassociation arguments - even if we get the pressure and temp so high water disassociates, it will take energy to do that.
Then when the temps cool slighly as the piston heads down, the hydrogen will "burn" and recombine giving the energy back to the system. When done, that is all a wash.
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Hello drmiller100,
Yep. If you add extra water the energy that disassociates it comes when the temperature in the combustion process is high, and the energy you get back comes at a lower temperature so you lose thermodynamic efficiency. So it's a wash less a little bit. In the real world this happens all the time, but the energy recycled through is immeasurably small and the lost bit is a small fraction of that.
While the decomposed water is in the mix it is just a couple of gases: ideal gas law for that fraction, so no benefit.
-mort