Thermoacoustic Refrigeration: Low-Temperature Applications and Optimization

Abstract

During the past two decades the thermoacoustic refrigeration and prime mover cycle has gained importance in a variety of refrigeration applications. Sound can be used to generate temperature differences that allow the transport of heat from a low temperature reservoir to an ambient at higher temperature, resulting in a thermoacoustic refrigeration system. The thermoacoustic energy pumping cycle can also be reversed and a temperature difference imposed along the stack plates can lead to sound generation. In this situation the thermoacoustic system operates as a prime mover. Sound generated by means of the thermoacoustic energy conversion process can be utilized to drive different types of refrigeration devices that require oscillatory flow for their operation, such thermoacoustic refrigerators, pulse tubes and Stirling engines. In order for a thermoacoustic refrigeration or prime mover system as well as a thermoacoustic prime mover driving a non-thermoacoustic refrigeration system to be competitive on the current market, it has to be optimized in order to improve its efficiency. Depending on the application, different optimization criteria can be used to design such systems, and some of these criteria are discussed in the paper.