Jeff Spitzer wrote:

At 09:28 AM 2/18/99 -0800, you wrote:

Byron Brandon Ward wrote:

Which brings up another question I've always wondered which is if there is
as much energy in heat going out the radiator as the e-shaft why doesn't a
decent (homebuilt) system capture even a little bit of it. Even 5% on a
200hp engine is a significant amount. In my mind one of the main
advantages of a rotary (or any liquid cooled engine for that matter) is
that cooling can be made much more efficient and things are neater up
front.

In basic thermo terms the way you get work from heat is through compression
and expansion.  The engine compresses air, then heats it through combustion
and finally expands it to extract work.  An engine with a compression ratio
of 1.03 would not make much power even if you dumped a ton of fuel in it.
Sorry to say that's about the pressure ratio your cooling system is working
with.  Note that the faster and higher you go the better the pressure ratio
and hence energy conversion gets.  At about Mach 1 you actually have a
viable ramjet, at 200 MPH a ramjet isn't worth a shit.

BTW things get a lot more interesting when you throw temperature
into the equation (P1 X V1) / T1 = (P2 X V2) / T2

Things get more correct when you include heat, not just more interesting.
To properly size the system the actual density at any location must be
considered.

Jeff Spitzer

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