Experimental evaluation of transient heat and mass transfer during regeneration in multilayer fixed-bed binder-free desiccant dehumidifier

In this study, regeneration experiments were performed in a previously developed multilayer fixed-bed, binder-free desiccant dehumidifier (MFBDD) in order to investigate the transient heat and mass transfer characteristics during the desorption of condensed water from desiccant material inside the device. A microsphere silica gel (M.S.GEL manufactured by AGC Si-Tech. Co., Ltd., Japan) having a pore diameter of 2.7 nm was used as the desiccant, which was feasible for regeneration at a temperature slightly above 50 °C. To prevent heat loss during regeneration, the test section was placed inside a constant-temperature oven. Experiments were performed under several regeneration conditions to investigate the influence of temperature, humidity, and flow velocity of the regeneration air on the heat and mass transfer characteristics of the device. The influence of heat loss from the test section to the surroundings during regeneration was also determined by precisely controlling the oven temperature. The results revealed that the regeneration capacity of the device improved with an increase in the regeneration air temperature. However, the maximum temperature of regeneration air should be optimized for energy-efficient operation of the device according to the regeneration conditions.