Advanced Open-Cycle Desiccant Cooling System

Abstract

The concept of staged regeneration as means of improving the desiccant cooling system performance is the subject of investigation in this study. In the staged regeneration, the regeneration section of desiccant dehumidifier is divided into two parts and only the latter fraction is subjected to the desorption air stream which has been heated to the desired regeneration temperature. In the present work, the mathematical model describing the heat and mass transfer processes that occur during sorption of moisture in the desiccnnt dehumidifier includes both the gas-side (film) and solid-side resistances for heat and mass transports. The moisture diffusion in the desiccant material is expressed by gas-phase diffusion and surface diffusion. Effects of several parameters on the performance of desiccant cooling system with staged regeneration are investigated and the results of present model are compared with those of the lumped-resistance model. Results of this study show that coefficient of perfomnnce of the desiccant cooling system can be substantially improved by using the staged regeneration concept. There is an optimum stage fraction and optimum cycle time for given system parmeters and operating conditions. The results also indicate that the cooling system performance is higher than that predicted by the lumped-resistance model.