Acoustically Driven Sorption Heat Pump

Abstract

Recent years have seen a dramatic rise in global cooling demand, driven by economic growth and climate change, and resulting in an increasing share of the total electric power consumption. Meanwhile, the ubiquitous vapor-compression air conditioners use refrigerants, which contribute greatly to global emission of greenhouse gases. In order to reduce the strain on electric grids, heat-driven technologies must be developed. Here, an acoustic driven sorption cooling device is examined experimentally and theoretically. The device can potentially utilize heat or electricity as a power input, uses environmentally benign working fluids, and offers simple, reliable construction with little to no moving parts. The results demonstrate the sorption-mediated, time-averaged heat-transfer mechanism, driven by the acoustic field. An unoptimized, proof-of-concept device is operated using a mixture of atmospheric air and either water or methanol, with cordierite and zeolite sorbents. The device is able to achieve temperature differentials $>30{\phantom{\rule{0.1em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. Moreover, a coefficient of performance of approximately 3 (based on the acoustic power input) is achieved at a temperature difference of $10{\phantom{\rule{0.1em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$. Theoretical calculations provide an outlook on the operation of such technology, compared with existing cooling technologies, demonstrating its potential for achieving high efficiencies. Finally, prospects for further development are discussed.