Experimental and theoretical study on water vapor isothermal adsorption-desorption characteristics of desiccant coated adsorber

Open air channels coated with porous desiccant are widely applied in solid desiccant cooling systems. In this study, the isothermal adsorption and desorption characteristics of silica gel coated single-channel adsorber were investigated. A modified LDF model considering airand solid-side resistances was derived to evaluate the kinetics and estimate the total mass transfer rate for numerical modelling. Results show that the modified LDF model can well describe the dynamic behavior of isothermal dehumidification. A new numerical model predicting the mass transfer characteristics of dehumidification process was proposed and strictly validated. Parametric studies reveal that the moisture transfer strongly depends on kinetic constants, isotherm shapes and thermal boundaries. The higher kinetic constants, the larger adsorption/desorption rate and the faster equilibrium. It was found that neither too high nor too low shape factor R are conducive to improve dehumidification capacity. The isotherm with R = 0.1 is considered as the optimum isotherm shape. With the transition of thermal boundary from ideal isothermal to adiabatic condition, the mass transfer performance decreases. The peak value of transient mass transfer rate of adsorption process under ideal isothermal boundary is almost twice and 2.6 times higher than these of the third type thermal boundary and adiabatic boundary, respectively. (c) 2022 Elsevier Ltd. All rights reserved