Evaluation of Stirling engine appendix gap losses

Abstract

The efficiency of a Stirling engine can be strongly influenced by the heat transfer losses associated with its appendix gap region. The cyclic energy flows in this region are related to the temperature gradient along the piston and cylinder partition walls, the reciprocating motion of the piston, the pressure variation in the Stirling cycle and the leakage flow across the cold-end seal. This paper outlines a numerical model to simulate these cyclic energy flows and the subsequent effort to correlate it with engine test data. The sensitivity of the appendix gap loss to selected parameters and comparisons with test results are presented.