A thermoacoustic refrigerator driven by a low temperature-differential, high-efficiency multistage thermoacoustic engine

A multistage thermoacoustic engine could potentially lower the critical onset temperature, which in turn is known to be successfully lowered with multistage amplification. However, not all of the regenerators of a multistage thermoacoustic engine can be set at the peak of the real part of the acoustic impedance distribution and therefore efficiency is generally low. The development of a thermoacoustic engine that has both low temperature oscillation and high efficiency is essential for any practical application. We performed a numerical calculation for a double-loop type thermoacoustic refrigerator driven by a multistage thermoacoustic engine. We determine the configuration that enables a low temperature oscillation and high efficiency. We also obtain the dependency on the temperature ratio of the prime mover for the temperature ratio of the refrigerator, acoustic field, and thermal efficiency. A low temperature drive with high efficiency can be achieved within a multistage thermoacoustic engine.