An axisymmetric computational fluid dynamics approach to the analysis of the working process of a solar stirling engine

Abstract

The use of computational fluid dynamics (CFD) models significantly extends the capabilities for the detailed analysis of the complex heat transfer and gas dynamic processes that occur in the internal gas circuit of a Stirling engine by more accurately predicting the engine's performance. This accurate data on operational characteristics of the engine can then contribute to more precise calculations of the dimensions of a parabolic concentrator in a dish/Stirling engine installation. In this paper a successful axisymmetric CFD simulation of a solar "V"-type Stirling engine is described for the first time. The standard - turbulence model, with a moving mesh to reflect the reciprocating motion of the pistons, has been employed for the analysis of the engine's working process. The gas temperature and pressure distributions and velocity fields in the internal gas circuit of the machine have been obtained and the pressure-volume diagrams have been calculated. Comparison of the numerical results produced from the axisymmetric CFD simulation of the engine's working process with those computed with the use of second-order mathematical analysis shows that there are considerable differences. In particular, analysis of the data obtained indicates that the gas temperature in the compression space depends on the location in the cylinder for the given moment in the cycle and it may differ substantially from being harmonic in time.