Synthetical performance analysis of phase-change thermoacoustic regenerators and stacks

Introducing a phase-change component to thermoacoustic regenerators or stacks increases the complexity of the thermoacoustic conversion process, and currently the analysis of relevant influencing factors is still limited. This paper introduces a comprehensive analysis method for wet regenerators or stacks by deriving normalized parameters, including acoustic power, efficiency, and temperature gradient. The analysis encompasses various influencing factors and impedance phases, revealing that the mass diffusion process enhances performance and lowers the onset threshold. Optimized wet regenerators with a traveling-wave field exhibit an efficiency 0.239 higher than that of dry regenerators, and their acoustic power surpasses dry regenerators by a maximum factor of 41.8. Additionally, the required length ranges and hydraulic radius for onset become more extensive. Furthermore, the onset temperature gradient decreases greatly, in a standing-wave system, wet stacks achieve a minimum temperature gradient 0.27 times that of dry stacks. The mass diffusion process augments the degree of reversibility in wet regenerators. Optimized wet regenerators tend to achieve high performance with smaller radius and impedance phases closer to 0° compared to the dry ones. This research offers valuable insights for designing, analyzing, and optimizing wet thermoacoustic regenerators or stacks.