Abstract:
A systematic approach to optimize the performance of thermoacoustic refrigerators by using the COP (coefficient of performance) is presented. For this purpose four main modules of the thermoacoustic refrigerator were identified: (i) the thermoacoustic core, (ii) the resonance tube, (iii) the acoustic driver, and (iv) the heat exchangers. The main objective of the analysis was the optimization of the thermoacoustic core, which consists of the stack region of a thermoacoustic refrigerator, by applying the short stack boundary layer approximation. For the enthalpy and work flux equations of the short stack boundary layer approximation, which are the base for the calculations of the thermoacoustic core's COP, 20 independent design parameters were identified, and summarized in a multidimensional parameter space. Introducing a normalized multidimensional parameter space the number of design parameters was reduced to ten. Setting limits on the normalized design parameters allowed us to identify the three most significant design parameters: (i) normalized stack length, (ii) normalized stack center position, and (iii) normalized temperature difference. Theoretical calculations of the thermoacoustic core's COP indicate competitive values with commercially available refrigeration techniques. [Work supported by the Office of Naval Research; Martin Wetzel is also supported by a scholarship from DAAD.]