Investigations on adsorption – Evaporation characteristics and cycle time effects of integrated desiccant coated M-cycle cooler

Abstract

This paper looks into the possibility of undertaking simultaneous dehumidification and evaporative cooling in a single heat exchanger, through the conceptualisation of a desiccant-coated M-cycle cooler. The cooler utilises waste heat as a low-grade thermal energy input to regenerate the silica gel desiccant. The interplay between the adsorption and evaporation phenomena has been studied for the crossflow and counterflow configurations of the cooler. Partial differential equations have been formulated for both heat and mass transfer across each of the control volumes. Results obtained from the transient analysis reveal three distinctive temperature regimes of the counterflow configuration and two regimes for the crossflow configuration. It is also observed that the evaporative cooling effects are more predominant in the counterflow setup. Cycle time analysis reveals that the counterflow configuration has greater operational times and lower downtimes as compared to the crossflow configuration. At 82.5 °C, the operational time of counterflow configuration is observed to be double the downtime, thereby doubling its cooling capacity. Thus, the study showcases the potential of utilising low-grade waste heat to develop an integrated adsorption-evaporation cooler for air-conditioning applications.