Performance of Thermoacoustic Refrigerators: Cooling Load and Coefficient of Performance

Abstract

Thermoacoustic refrigeration is an environmentally safe refrigeration technology that has evolved over the past three decades [1–5]. The influence of working fluid on the performance of the thermoacoustic refrigerator (TAR) expressed in terms of the cooling load and the coefficient of performance is discussed in the paper. The calculations rely on the short stack boundary layer approximation. A simple model of a one-dimensional half wavelength resonance tube equipped with stack plates and a pair of heat exchangers was used as the physical model. It is known that a TAR with noble gases and their mixtures as working fluids can achieve high values of the coefficient of performance (COP) because of small Prandtl number values. The present study revealed and quantified that cooling load behavior is quite different from the performance in terms of the COP: the highest cooling load is achieved with pure Helium as the working fluid. A reason is the very high sound speed in Helium. TARs with Helium as the working fluids deliver the highest cooling load of all gases and their mixtures examined here, therefore it has been suggested as a limiting case of the most powerful TAR. The influence of geometry and thermophysical parameters of the device on TAR performance was studied systematically and a performance sensitiviy analysis was presented with particular emphasis on TAR cooling load.