Investigation on the thermoacoustic conversion characteristic of regenerator

Regenerator is the core component in the regenerative heat engines, such as thermoacoustic heat engine, and Stirling heat engine. The regenerator has a porous configuration, in which the thermoacoustic effect happens between the working gas and solid wall converting heat into acoustic work. In this paper, a novel experimental setup was developed to investigate the thermoacoustic conversion characteristic of the regenerator. In this system, two linear motors acted as compressors to provide acoustic work for the regenerator and the other two linear motors served as alternators to consume the acoustic work out of the regenerator. By changing the impedance of the alternators, the phase difference between the volume velocities at the two ends of the regenerator could be varied within a large range. In the experiments, the influence of phase difference, heating temperature and different materials on the performance of the regenerator were studied in detail. According to the experimental results, the output acoustic power increased when the phase difference between velocities of the compression and expansion pistons increased within this phase angle range. And the thermoacoustic efficiency had different optimum values with different heating temperatures. Additionally, it also shows that flow resistance and heat transfer area were very important to the performance. In the experiments, a maximum output acoustic power of 715 W and a highest thermoacoustic efficiency of 35.6% were obtained with stack and random fiber type regenerators respectively under 4 MPa pressurized helium and 650 °C heating temperature. This work provides an efficient way to investigate the thermoacoustic conversion characteristic of the regenerator. It also provides some clues to the regenerator design.