Modeling and analysis of a dual-acoustic-driver thermoacoustic heat pump

Abstract

Thermoacoustic heat pumps (TAHPs) can be used for heating and/or cooling purposes. Current designs of travelling-wave TAHPs normally employ a single acoustic driver and rely on a looped pipe to establish and maintain the required acoustic field. The resultant system is thereby bulky and expensive, detracting from the structure simplicity and low-cost advantages of thermoacoustic technology. To address this issue, this paper investigates the dual-acoustic-driver concept that can significantly increase the system’s compactness. Theoretical analyses are conducted for the dual-acoustic-driver TAHP, and the acoustic and temperature fields in the thermoacoustic core are examined. Parametric studies are undertaken to investigate the effects of acoustic drivers on the acoustic and thermal characteristics of the TAHP. It is found that, as the frequency of acoustic drivers changes, the acoustic field in the thermoacoustic (TA) core could be dominated by a standing, traveling, or hybrid standing-traveling wave. The temperature distribution within the TA core and temperature difference between the core ends will change accordingly. Results show that the temperature difference is non-zero only when the acoustic field contains a traveling-wave component. To obtain a large temperature difference, the acoustic drivers should be driven near resonance frequencies at which the acoustic field is hybrid and the pressure amplitude is large. This study gains new insights into the working mechanisms behind the dual-acoustic-driver TAHP concept, paving the way for developing compact, efficient, and high-power-density TAHPs for industrial waste heat recovery.