A computational fluid dynamics study on the heat transfer characteristics of the working cycle of a β-type Stirling engine

•An in-house CFD code has been developed to simulate a β-type Stirling engine.•Temperature distribution is highly non-uniform across the engine volume.•Impingement is the major heat transfer mechanism in the engine.•The motions of displace and power piston are also important for heat transfer. A compressible CFD code has been developed to study the heat transfer characteristics of a β-type Stirling engine with a very simple design and geometry. The results include temperature contours, velocity vectors, and distributions of local heat flux along solid boundaries at several important time steps as well as variations of average temperatures, integrated rates of heat input, heat output, and engine power. It is found that impingement is the major heat transfer mechanism in the expansion and compression chamber, and the temperature distribution is highly non-uniform across the engine at any given moment. The results, especially the rates of heat transfer, are quite different from those obtained by a second-order model. The variations of heat transfer rates are much more complicated than the simple variations returned by the second-order model. This study sheds light into the complex heat transfer mechanism inside the Stirling engine and is very helpful to the understanding of the fundamental process of the engine cycle.