re Re: Ceramic coating EM's - II

["Smith, Kirby A" <kirby.a.smith@lmco.com>]

quk@isham-research.demon.co.uk (Phil Payne)responded:

	In message <37FA96F6.841C9718@adams.com> The Murphy-Fahlgren Family
writes:

	> Say what?  The turbine converts heat into mechanical energy,
	> id est, it _removes_ heat from the system.

	No, it converts kinetic energy into heat.  The fact that exhaust gas
	is hot has nothing to do with it - it would be just as happy with
	cold gas input.

Hmmm Phil, I'm not sure I would embrace this perspective.  Your first
sentence is literally true over the entire system.  The exhaust kinetic
energy is used to perform work on the exhaust turbine (which is attached to
the intake side compressor of course, pressurizing the intake manifold and
in the process generating heat).  If the gas kinetic energy is partially
used, the temperature of the gas will fall for that reason, as well as due
to the drop from any pressure fall across the turbine.  So the turbine, a
passive device, does not add heat to the _system_, it can only lose a little
thru its surface area.  It does extract heat from the exhaust to do work on
the intake.  It is the fuel that adds heat to the system, as I am sure you
know.

I do not believe your second sentence agrees with my understanding of turbos
from books I have read.  I believe the shape of turbines, whether jet engine
or in turbosuperchargers, is designed to use both flow and temperature.
This may all be semantic, as heat is kinetic energy in a gas.  The kinetic
energy is both random and directional, and both may be used in a heat
engine.

Kirby A. Smith   New Hampshire USA
1988 90q Titanium gray, 182 kmi
1988 90q Stone gray, 187 kmi 
1995 S6 Pearl effect, 82 kmi