Design and optimisation of domestic-scale thermoacoustic refrigerator

Abstract

This research study aimed to evaluate the performance of a standing wave thermoacoustic refrigerator and optimise the stack length and position for a single stack material. Thermoacoustic refrigerator (TAR) generally has a low coefficient of performance (COP). This has negatively impacted its development. There has been research to improve its COP, which has mostly focused on optimising the system. Numerical and experimental have been used to optimise various components of TAR. This research study combined the experimental work and numerical modelling of the standing wave TAR. Thirty experiments were conducted over three months. The experiments were done for three stack positions of 30 mm, 40 mm, and 50 mm. At each stack position, stacks of lengths of 25 mm, 35 mm, 45 mm, 55 mm, and 65 mm. In addition, numerical modelling of TAR performance was done for the three positions, with the five stack lengths for each position. The numerical modelling was done using the commercial Multiphysics software. The experiments and numerical modelling were followed by optimisation. The optimisation of the experimental data identified the optimal stack configuration as a stack position of 55 mm and a stack length of 25 mm, achieving a COP of 0.33. The optimal configuration yielded ΔT=8°C, COP=0.33, TC=25.1°C and QC=0.0532 W. On the other hand, the optimisation of numerical modelling data identified the optimal stack configuration as a stack position of 30 mm and a stack length of 25 mm, achieving a COP of 1.27. The optimal configuration yielded ΔT=8.5 K and COP=0.33. The experimental work and numerical modelling agreed regarding stack length. They both indicated an optimal stack length of 25 mm, suggesting that short stack lengths are good for a high COP while maintaining other performance metrics within acceptable ranges. The experimental work and numerical modelling differed in the optimal stack position. As a result, this study could not uncover the influence of stack position as far as optimising for a high COP is concerned.