Numerical and experimental study of a novel four-stage thermoacoustic engine with multi-looped structure

The thermoacoustically driven pulse tube refrigeration system has remarkable advantages including simple structure, high reliability, environmentally friendly working gas, and potentially high efficiency. This technology holds substantial potential for applications in natural gas liquefaction and waste heat recovery. A novel thermoacoustically driven pulse tube cryocooler (THE-PTC) system is proposed, including a conventional bypass structure and a novel multi-looped structure. By sharing the resonance tube between THE and PTC, the compactness of the system and the efficiency of acoustic power are simultaneously increased with the multi-looped structure. Calculations show that the multi-looped structure can increase cooling capacity by 11.6 % or cooling efficiency by 5.67 % compared to the conventional bypass structure. By analyzing the acoustic field distribution and impedance matching, the effects of structural parameters on system performance are illustrated. The multi-looped structure THE is predicted to be able to output 60 kW acoustic power with designed working pressure and heating temperature. The experimental setup of the THE-PTC system was constructed and experimentally achieved an acoustic power output efficiency of 16.15 % and an acoustic power output of 4 × 2100 W. The experimental results are in fairly good agreement with the model. This research shows the prospect of high-power THE-PTC systems in the field of gas liquefaction.