One-Dimensional Model Incorporated with Mechanical Loss and Auxiliary Power for Evaluating Thermodynamic Performance of Stirling Engine

Stirling engines are regarded as an efficient and promising power system for underwater devices. Currently, many models have been used to evaluate thermodynamic performance of Stirling engine, but in which mechanical loss and auxiliary power still cannot be modeled with proper mathematical models. A four-cylinder double-acting Stirling engine for Unmanned Underwater Vehicle (UUV) is discussed in this paper. Referring to the Stirling engine experimental results from National Aeronautics and Space Administration (NASA), a one-dimensional model incorporated with empirical equations of mechanical loss and auxiliary power obtained from experiments is presented. The P-40 Stirling engine with sufficient testing results from NASA is utilized to validate the accuracy of the modified one-dimensional model. And the comparison results suggest good agreement between testing and simulation results. The output power maximum error of theoretical analysis results is less than 18% over testing results, and the maximum error of input power is no more than 9 %. In short, the one-dimensional model is adequate to evaluate the thermodynamic performance of the Stirling engine.