Numerical study of electric power generation from a liquid piston thermoacoustic Stirling engine

The liquid piston thermoacoustic stirling engine (LPTSE) is a type of Stirling engine that utilizes the reciprocating motion of liquid columns within U-tubes instead of a traditional mechanical piston, enabling the working gas to experience the Stirling-like thermodynamic cycles. To date, LPTSE has primarily been used for cooling purposes; however, it also holds the potential for electricity generation. This paper presents a numerical investigation of methods for generating electric power from LPTSE. The first method involves the use of a linear alternator to harness the oscillation of the gas column, while the second method employs a float-type alternator to utilize the oscillation of the liquid column. Numerical simulations were performed utilizing DeltaEC, a dedicated design tool founded on the principles of linear thermoacoustics theory. The results showed that proposed methods did not alter the acoustic fields in the regenerator, indicating that the engine operates with the Stirling-like thermodynamic cycle and achieves high thermal efficiency. The linear alternator generated an electric power of 0.2 W with a thermal-to-electric efficiency of 2.48\(\%\) under a load resistance of 1 \(\Omega\), whereas the float-type alternator produced an electric power of 0.7 W with thermal-to-electric efficiency of 4.5\(\%\) under a load resistance of 7 \(\Omega\). The research results presented in this paper offered perspectives on electricity generation from the LPTSE.