Numerical investigation on key parameters of a double-acting free piston Stirling generator

Exploring efficient renewable energy conversion devices is one of the vital subjects to address the current energy crisis. Double-acting free piston Stirling generator is a promising type of Stirling generator with the advantages of high efficiency and wide energy adaptability, so it has a bright future in the energy sector. In this paper, the SAGE software and acoustic-electric coupling model are used in the generator system for exploring the influence of key parameters on performance. The results indicate that the system exhibits higher power output when the unit number is 4 or 5. The piston clearance may induce greater exergy losses in a double-acting configuration, because of the greater pressure difference and the temperature difference on the two sides of the pistons. Reducing dead volume can improve power density and efficiency. Moreover, any parameter inconsistencies between units can affect the output electric powers of all units. Further investigation reveals that this issue can be effectively addressed by adjusting the external resistance and reactance. This work may offer some guidance for the design of double-acting free piston Stirling electric generators.