Experimental and numerical analysis of a liquid-piston Stirling engine with multiple unit sections

This study investigates a liquid-piston Stirling engine in which the solid pistons of conventional Stirling engines are replaced by U-shaped liquid columns. The engine has a loop structure made of a chain of unit sections. consisting of liquid columns and gas columns. Simultaneous measurements of pressure and velocity oscillations in the gas column provide experimental evidence of the execution of the Stirling thermodynamic cycle with relatively small viscous losses in the regenerator. An analysis based on thermoacoustic theory clarifies how many unit sections should be used to build the engine. The results show that engines composed of three to five unit sections ensure stable low-temperature-ratio operation.