Active control of heat transport inside the porous material of a looped-tube dual-acoustic-driver thermoacoustic refrigerator

Abstract

Compared with passive control approaches, it is more convenient to control the heat transport within the porous material of electrically-driven thermoacoustic refrigerators (TARs) by actively modulating the operating parameters of the acoustic driver(s). This study concentrates on the heat transport within the porous material of a looped-tube TAR driven by two acoustic drivers. Analytical models based on the linear theory are established to describe the acoustic field inside the TAR and the temperature field within the porous material. It is found that the heat transport within the porous material of the looped-tube TAR can be modulated by changing the driving frequency, phase difference and positions of acoustic drivers. The resonance frequencies of the looped-tube TAR are not affected by the phase difference but are influenced by the positions of acoustic drivers. Different from thermally-driven TARs that prefer a traveling-wave acoustic field, electrically-driven TARs should operate at resonance frequencies at which a standing wave dominates, and most of the work input from the acoustic drivers is used to pump heat. To achieve a large temperature difference, the two acoustic drivers should be placed asymmetrically at two sides of the porous material. This study offers a generic theoretical framework to investigate electrically-driven TARs with one or multiple porous materials and acoustic drivers, providing useful guidelines for the development of high-performance TARs as a green technology in low-temperature engineering.