Characterization of inexpensive stack materials for use in standing wave thermoacoustic refrigerators

Stacks are some of the vital parts of standing wave thermoacoustic refrigerators where the energy transfer occurs thanks to a thermoacoustic effect. There are two main issues regarding stacks. Firstly, stacks might be costly due to costs of materials and secondly, their fabrication costs may be prohibitive due to the involved/impractical assembly processes. One of the solutions to these issues could be stacks made of some "random" materials such as stainless steel wool or copper scourers which are low-cost, widely available and easy to shape to take the form of a stack. Moreover, parallel plate stacks can be manually made by using regular and inexpensive materials such as Mylar sheets. Some chosen stack materials such as mentioned above have been used and studied by carrying out measurements on a standing wave thermoacoustic refrigerator working in a half-wavelength mode. This work aims to investigate the thermal performance of such inexpensive stack materials. It is believed that this investigation will be beneficial for developing low-cost thermoacoustic refrigerators for both domestic and commercial applications.