Re: "Who Killed the Electric Car?" opens July 14th

In message <tNadnRjcP_TbeCvZnZ2dnUVZ_t6dnZ2d@xxxxxxx>, Paul F. Dietz
<dietz@xxxxxxx> writes
Doug Wickstrom wrote:

Preheating the input stream _decreases_ efficiency.

They preheat the air after compression, but before the fuel
is added and burned. This only makes sense if your
turbine operates at moderate pressure. At high pressure,
the compressed air is too hot and the exhaust (which
has been expanded more) is too cool.

The Carnot cycle is the determinant for efficiency in getting work out
of a heat engine, and the key factor is the difference between the input
fluid's temperature (in this case air) and its output temperature. It's
why steam engines are less efficient than internal combustion engines,
why gas turbines are more efficient than IC engines and why rockets are
the best. Pre-heating the incoming air reduces the efficiency.

Stationary turbine-generators are used in industry for local power plus
process heat using the exhaust; in one case I know of it's used to heat
a large TV studio complex plus provide power for the studio's operation.
Any excess power is sold back to the local generation company.

I've thought turbines would be interesting as components
of a series hybrid drivetrain.

This was done in the 40s, a combination turbine and diesel engine meant
for aircraft. It was a mechanical horror as you might expect.
--
To reply, my gmail address is nojay1 Robert Sneddon
.

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