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

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

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.

Um, did you read what I wrote? Of course preheating the air before
compression is silly, since it increases the work needed to compress
the air. But the regenerator operates *after* compression, where it
merely serves to save fuel (some of the heat that would have to be
added by combustion is instead recuperated from the exhaust, where
it would otherwise be wasted). This increases efficiency, not decreases,
if the exhaust temperature would otherwise be higher than the
compressor outlet temperature.

Here's an example of a microturbine currently on the market that
includes this kind of recuperator:

http://www.capstoneturbine.com/technology/techUnderHood.asp

I believe this company originally was targeting series hybrid
vehicles, but found that stationary microgenerators (with
cogeneration) was a more fruitful market.

Paul
.

Relevant Pages

  • Re: Quasiturbine - Over unity air motor ?
    ... > on efficiency in a recent post about the ... because of volume reduction and because of temperature increase. ... the total amount of heat continuously removed ... the heat accumulated at the end of an adiabatic compression ...
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  • Re: Quasiturbine - Over unity air motor ?
    ... > on efficiency in a recent post about the ... because of volume reduction and because of temperature increase. ... the total amount of heat continuously removed ... the heat accumulated at the end of an adiabatic compression ...
    (sci.energy.hydrogen)
  • Re: Enclosure volume
    ... temperature of the air in the box accordingly. ... compress the air in then box, it raises the temperature. ... takes to move the diaphragm a specific distance, i.e., the "spring ... Or, succinctly, the compression of a given volume of air is different ...
    (rec.audio.tech)
  • Re: Enclosure volume
    ... temperature of the air in the box accordingly. ... compress the air in then box, it raises the temperature. ... takes to move the diaphragm a specific distance, i.e., the "spring ... Or, succinctly, the compression of a given volume of air is different ...
    (rec.audio.tech)
  • Re: Heat pump question
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    (alt.home.repair)