Stirling/ Electric hybrid

[Joe Blake]

http://www.gizmag.com/dean-kamen-segway-hybrid-scooter/12096/

http://www.gizmag.com/pictures/hero//12096_29060910341.jpg

This looks pretty interesting. The Stirling engine itself only runs a generator to power an electric drive.

What I find more interesting is the note at the bottom that Honda is working on a heat scavenging system using a Stirling engine to harness some of the waste heat from a conventional car.

Should have been done long ago.

Joe

[Dave Turpin]

I agree. Some of the waste energy from the ICE has been used to spin a turbocharger, but I never understood why more could not be used. Ceramic piston-cylinder arrangements have been widely disregarded simply because the exhaust becomes SO HOT without the usual 80% thermal losses to the cooling system, that many think it would be dangerous. But why not use that heat in a Stirling? 100 miles to the gallon becomes a lot more feasible.

[Bill von]

I agree. Some of the waste energy from the ICE has been used to spin a turbocharger, but I never understood why more could not be used. Ceramic piston-cylinder arrangements have been widely disregarded simply because the exhaust becomes SO HOT without the usual 80% thermal losses to the cooling system, that many think it would be dangerous. But why not use that heat in a Stirling? 100 miles to the gallon becomes a lot more feasible.
If the exhaust is SO HOT then the total efficiency of the engine is very low. So while a Stirling could recover some of it, you'd start off so low that it would be very hard to reach even the efficiency of a conventional Atkinson engine (over 40%.)