Displacer piston material
Posted: Sat Oct 21, 2006 11:37 pm
Correct me if I am wrong, but wouldnt making the displacer piston out of a non heat conducting material be benefitial to the overall efficiency of the engine?
The answer is "yes and no".
If the displacer is to be a continuous cylinder, a non-conductive material is well suited. I've read in many places that stainless steel is best. The biggest drawback to stainless is that it is relatively heavy; if you use it, try to get it as thin as possible to reduce the weight. If you can't get thin stainless, aluminum will work too, though it is much more heat conductive. It has the advantage of being much lighter. Ultimately, it will depend on your design.