Simulation of Ground Power Unit – 3 (GPU3) Stirling Engine with Air as Working Fluid

Abstract

Abstract The immediate need to mitigate climate change presents a chance to move civilization in the direction of a more sustainable future. A Stirling Engine has multi-fuel capability such as Biomass, Solar Thermal and Waste Heat and hence can contribute significantly to the energy mix of fuel sources. The most common working fluids for Stirling engines are hydrogen, helium, and air, with air being the least expensive and safest. Studies analysing Stirling Engine performance with 3D CFD are limited, and even fewer use air as the working fluid. This research presents a novel 3D CFD analysis of the Ground Power Unit – 3 (GPU3) Stirling Engine with air as the working fluid using ANSYS Fluent. The fluid domain was modelled in SolidWorks and 1/8th of the geometry was used for simulation with realizable EWT k-ε as eddy viscosity model. It was found that on average there was a reduction in power output by 50% when air was used as working fluid against helium as working fluid. The engine's power output decreases as the engine's speed increases. The impinging effect contributes to vortex formation and temperature variation within the engine components was non-sinusoidal, this is inline with similar studies performed on GPU-3 Stirling engine.