Performance enhancement of desiccant wheels by adsorption/desorption in stages with type-S isotherm desiccants

Abstract

Desiccant wheels coated with desiccants possessing a single kind of adsorption isotherm face the drawback that the moisture transfer driving force decreases along the direction of air flow in the channel, which hinders the efficiency of regeneration and dehumidification processes. In this study, a new concept of adsorption/desorption in stages with type-S isotherm desiccants was proposed to improve the performance of a counter flow type desiccant wheel by increasing the moisture transfer driving force during both dehumidification and regeneration processes. The numerical results show that compared with conventional wheel made up of silica gel, the two desiccant wheels with various hypothetical type-S isotherm desiccants designed in this study output air with more stable humidity during dehumidification, and have superior performance when both cycling time (tcyc) is high and regeneration temperature (Tr,i) exceeds the critical value.