Using power ultrasound for the regeneration of dehumidizers in desiccant air-conditioning systems: A review of prospective studies and unexplored issues

Regeneration of dehumidizers is the most important stage in the working cycle of desiccant system. The lower regeneration temperature will be favorable for the energy efficiency of the whole system. Ultrasonic technology may be a promising method of dehydration applied to the regeneration of desiccant. As a non-heating method, the power ultrasonic may help lower the regeneration temperature and bring about energy savings. In the present paper, the mechanism of ultrasonic regeneration is set forth based on the ultrasonic theory as well as the mass transfer model in solid–gas and liquid–gas system. The recent studies related to ultrasonic dehydration are extensively reviewed, which is of significant reference to the study of desiccant regeneration assisted by power ultrasound. In addition, this work gives the basic ideas of ultrasonic dehydrator for solid/liquid-desiccant regeneration, which will promote the development of relevant equipments. Finally, some unexplored issues on this topic are addressed, including insight into the effects of ultrasonic on the regeneration, drying kinetics model for ultrasonic regeneration and the challenges possibly faced for the ultrasonic transducer development.