Abstract
An explanation of second low efficiency was tried. In the trial, a low temperature differential Stirling engine is described as an example. In case of gamma configuration Stirling engine, the maximum width of volume fluctuation cased by a reciprocation of the displacer is limited by a function of temperature ratio. The function of temperature ratio is similar with the equation of Carnot efficiency. Actually, the value is the ratio of volume fluctuation and stroke volume of displacer. The value is not the ratio of energy. However, the function suggests that indicated work is affected by the temperatures of heat source and heat sink. In addition, the temperature differences at two heat exchangers decrease the obtained indicated work. Calculation result caused by the heat source temperature and the heat sink temperature show the volume of reversible process. On the other hand, the calculated efficiency caused by the working fluid temperatures was the efficiency of irreversible process. Therefore, the comparison of indicated work and Carnot efficiency is affected by the temperature differences at two heat exchangers, and is useful to evaluate the performance of the Stirling engine.
