Kongtragool and Wongwises (2005a) theoretically investigated the power output of a gamma-configuration LTD Stirling engine. Former works on Stirling engine power output calculations were studied and discussed. They pointed out that the mean-pressure power formula was the most appropriate for LTD Stirling engine power output estimation. However, the hot-space and cold-space
working fluid temperatures were needed in the mean-pressure power formula.