Robert J. Bradbury wrote:
> so your efficiency is (368-294)/368 = ~20%. Going to LN2 bricks
> as the sink @ 63K gives you (368-63)/368 = 82%. So your engine
> efficiency goes way up. Maybe you get 3-4x the MPG?
Nyet.
> Actually, there might be some problems with doing the calculation
> this way since the operating temperature that should be used
> might need to be closer to the fuel-air temperature in the cylinder.
Ja. The temperature you need for calculating Carnot efficiency
is the temperature of the exhaust when the exhaust valve opens.
It wouldnt buy much to dump the waste heat into a really cold
source other than you can get by with a smaller cooling system.
Nowthen, if you do have plenty of nitrogen bricks available,
there are thermal cycles that would be extremely attractive.
You could even theoretically use the air as a heat source
and the nitrogen bricks as a heat sink. Look ma, no fuel!
But of course, you would boil off the nitrogen bricks, and
the Carnot efficiency would be lousy as all hell. But it
would theoretically work. spike
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