Liquid piston Stirling engine loaded with self-rectifying turbine: Equivalent load analysis with orifice plate

This study delves into the optimal combination of a four-unit type liquid piston Stirling engine (LPSE) and a self-rectifying turbine for a thermoacoustic electric generator. The aim is to cater to rural electricity needs by utilizing air and water at ambient pressure as working fluids. To maximize the power transfer to the turbine, we examined the optimal turbine resistance, number of turbines, and installation locations using an orifice plate with an equivalent resistance to the turbine. Our experimental findings indicated that an orifice plate with an area ratio of 0.4 maximized power consumption when installed in one of four units of the LPSE. Numerical analysis further revealed that installing orifice plates in two adjacent units or all four units, while maintaining the proper phasing between pressure and velocity oscillations of the working gas at the regenerator, optimized total power consumption and thermal efficiency. Additionally, to satisfy the optimal resistance requirements, the turbine was designed with an enlarged rotor diameter, successfully achieving the target resistance. The proposed LPSE system, featuring a pipe diameter of 200 mm, demonstrated the potential to achieve a Carnot efficiency of over 20, underscoring its practical applicability. © 2025 The Authors