ICs are now well over thirty. Yes, they are reaching 50% range.

Figures typically quoted for car engines (SI) are very old. Modern ones
can get over 33-34% at full throttle (or at least near best specific
fuel consumption settings). Increases in compression ratio and other
factors account for this. 25% is very low for even an automotive or
truck Diesel. This value must be for an old one.

For powerplants reaching the 50% mark, these are stationary power
plants, for the most part. There is a scale efficiency factor at work
here (which is close to what started this thread),and they are very
large, and room for various regneration and other neat accessories.

mikee wrote:

Karl Townsend wrote:

I'm curious, they claim a thermal efficiency of 50%, nearly double that of
an automotive diesel. How do they do it? and why can't it be done in the
automotive size engine?

Karl

I don't think that 50% efficiency is thermodynamically possible. The best
designed fossil fuel powerplants barely make thirty percent. Carnot cycle
limitation?

Wonder where Pete is when we need him.

Mike Eberlein

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer