Numerical simulation of a looped tube 4-stage traveling-wave thermoacoustic engine

Background and Objectives: The technology of thermoacoustic energy conversion is one of the most promising technologies for converting thermal energy into electrical one. A brief review of the achievements in development of the multi-stage traveling-wave engines was made. The numerical simulation of a 4-stage engine with a load was done. The aim of research was to determine the engine parameters, required to achieve the maximum of efficiency of the system and the acoustic power on the load. Materials and Methods: Optimization of the engine parameters was carried out in the DeltaEC program. This program numerically integrates differential equations of thermoacoustics. The calculation procedure and the features of the calculation of a 4-stage engine are described. For the calculation the engine was taken with a looped tube resonator having the length 6 m and a 33 mm diameter of the stage. The temperature of the hot and cold heat exchangers in all Радиофизика, электроника,физика акустика Биофизика и медицинская calculations was 600 K and 300 K, respectively. The working gas is helium with a pressure of 1 MPa. Results: It has been shown that by sacrificing efficiency on the load, it is possible to significantly increase the output power on the load (about 24.5 times). When the system was tuned to the maximum power on the load, then the calculated efficiency at the load occurred 3.44 times less than that in the case of the system setting to the maximum efficiency of the system with the load. The optimal position of the load inside the resonator, the optimal ratio of the diameter of the stage and the diameter of the resonator were determined for the engine specified in the calculation. Recommendations for choosing the length of the stage are given. The optimum value of the hydraulic radius for heat exchangers and for the regenerator is one order of magnitude. Conclusion: The obtained results can be used to design 4-stage traveling-wave thermoacoustic engines.