Developing more efficient travelling-wave thermo-acoustic refrigerators: A review

The use of hazardous refrigerants in current refrigeration systems and their impact on environment have spurred much research into alternative technologies. Thermo-acoustic refrigeration is considered as one of the potential solution to the current search for environmental friendlier technology because of the absence of harmful refrigerants in the system. To date, most of the studies focus on the applicability of the technology toward a global agenda of a sustainable future. This paper summarizes recent development with regards to the designing and the performance of highly efficient traveling-wave thermo-acoustic refrigerators. Past studies discussing devices outputs namely the lowest temperature achieved, the cooling power and the coefficient of performance of travelling-wave refrigerators, are described. The review looks at the performance and the geometrical configuration of devices developed by previous researchers. A summary of the optimization targets and the outcomes achieved is described. It appears that most studies undertaken so far rely heavily on parametric approach, with single parameter being investigated while the others are kept constant during the optimization process. This opens the door for further use of advanced optimization techniques able to deal with parameters varying simultaneously, together with conflicting objectives, in order to identify global optimal solutions potentially more effective.