Energy efficiency comparison of Stirling engine types (α, β, and γ) using detailed CFD modeling

In this work, a comparison of the power output and the energy efficiency of three types of Stirling engine (α, β and γ) is conducted numerically. The three Stirling engine types do not include a regenerator. The Stirling engine is set to work between temperature limits of 300 K and 800 K, where air is adopted as the working fluid. To make the model more realistic, the internal radiation heat transfer inside the Stirling engine is considered. Also, the thermal properties of air are taken to be depending on temperature. The model is validated against an experimental data set from the literature. The results show that γ-type Stirling engine is being able to produce the highest power output and the highest thermal efficiency (9.223 W and 9.8%). It is followed by β-type Stirling engine (8.634 W and 7.5%). In contrast, the lowest performance is achieved by α-type Stirling engine (0.908 W and 1.8%). Therefore, the α-type Stirling engine is modified to have an annular connecting pipe instead of circular connecting pipe. Consequently, its performance improved dramatically to produce 9.856 W with a thermal efficiency of 10.5%.