Modified PSVL: A second order model for thermal simulation of Stirling engines based on convective-polytropic heat transfer of working spaces

The new numerical second order thermal model for the simulation of Stirling engines was presented. In the new model, the previously developed model of the present authors called PSVL model (polytropic analysis of Stirling engine with various losses) was modified based on coupling the convective heat transfer mechanism to polytropic expansion/compression processes. Furthermore, an exponential temperature distribution of the gas along the regenerator length was assumed in the new model. Similar to the original PSVL model, effects of heat and mass leakages were implemented in basic differential equations and the ordinary differential equations (ODE) system was numerically solved by fourth order Runge-Kutta methods. Results of the numerical model were corrected to include various non-idealities. Finally, the new polytropic convective model called modified PSVL was implemented to simulate he GPU-3 Stirling engine and the obtained results were compared with those of the previous thermal models as well as experimental data. It was found that the correction of PSVL led to better accuracy compared with the original PSVL as well as other models. Further, coupling the heat transfer to model caused a slightly greater amount of polytropic indexes than the original PSVL model. (C) 2015 Elsevier Ltd. All rights reserved.