High-efficiency and large-power-density thermoacoustic refrigerator for waste heat utilization

The utilization of industrial waste heat facilitates the reduction of energy consumption. The heat-driven thermoacoustic refrigerator (HDTR) can be powered by industrial waste heat to provide cooling, using environmentally benign inert gases without complex moving components. However, the current HDTRs are limited by inadequate cooling power density and low efficiency. This study presents an HDTR with mechanical resonators, thereby enhancing compactness and improving efficiency. Simulations reveal that employing the mechanical resonator instead of traditional gas resonator enhances cooling performance, with the cooling power density increasing from 15.04 kW/m 3 to 90.20 kW/m 3 and the COP rising from 0.29 to 0.51 at the heating temperature of 250 °C. Experiments demonstrate superior cooling performance of the system than the gas-resonator system. At the heating, ambient and cooling temperatures of 250 °C, 35 °C and 7 °C, the cooling power and COP are 2.76 kW and 0.48, respectively, and a maximum COP of 0.52 is achieved with a cooling temperature span of 20 °C. Furthermore, integrating a bypass tube can further enhance the efficiency with elevated cooling temperatures. This work enhances the power density and efficiency of HDTRs, putting forward a promising approach for efficient and reliable cooling utilizing waste heat.