Performance Analysis of the Small-Scale α-Type Stirling Engine Using Computational Fluid Dynamics Tools

This paper presents the computational fluid dynamics (CFD) model of small-scale α-type Stirling engine. The developed mathematical model comprises of unsteady Reynolds averaged Navier–Stokes set of equations, i.e., continuity, momentum, and energy equations; turbulence was modeled using standard κ–ω model. Moreover, presented numerical model covers all modes of heat transfer inside the engine: conduction, convection, and radiation. The model was built in the framework of the commercial CFD software ANSYS fluent. Piston movements were modeled using dynamic mesh capability in ANSYS fluent; their movement kinematics was described based on the crankshaft geometry and it was implemented in the model using user-defined functions written in C programming language and compiled with a core of the ANSYS fluent software. The developed numerical model was used to assess the performance of the analyzed Stirling engine. For this purpose, different performance measures were defined, including coefficient of performance (COP), exergy efficiency, and irreversibility factor. The proposed measures were applied to evaluate the influence of different heating strategies of the small-scale α-type Stirling engine.