A looped three-stage cascade traveling-wave thermoacoustically-driven cryocooler

This paper introduces a novel, looped, thermoacoustically-driven cryocooler, which is a promising candidate for natural gas liquefaction applications. Several thermoacoustic heat engines of different diameters are connected end-to-end by small-diameter resonance tubes. One pulse tube cooler is connected to the branch of the last-stage engine. This system is highly reliable, efficient, and compact for a looped configuration. In particular, the system realized cascade acoustic power amplification with only a single power output, which promises large capacity and structure simplicity. Here, a three-stage traveling-wave system is designed and numerically investigated. A comparison is made with the existing multiple pulse tube cryocoolers which indicates the superior performance of this novel system. The distributions of some key parameters and the exergy loss are presented and analyzed to better understand the energy conversion process. Two area ratios are found to be critical to the engine performance. According to the calculation, using 7 MPa pressurized helium gas, a cooling power of 1300 W and a total exergy efficiency of 15.7% is achieved at 110 K with 20.2 kW input heat at 923 K.