Preparation and Application of UiO-66 in Desiccant-Coated Heat Exchanger-Based Desiccant Cooling Systems

Abstract

Dehumidification performance of a high-efficient compact desiccant cooling component named desiccant-coated heat exchanger (DCHE) highly depends on coated desiccant materials. Currently, mesoporous silica gels and salt-supported silica gels have been extensively studied. Silica gels have limited adsorption quantity in the middle relative pressure range, while salt-supported silica gels have potential threat of corrosion. In this work, a metal–organic framework UiO-66 that can achieve good adsorption quantity without corrosion is reported. The equilibrium adsorption test shows that UiO-66 has promising water uptake, especially in the relative pressure range of 0.35–0.65. The adsorption kinetics test displays that UiO-66 exhibits desirable dynamic water uptakes and adsorption rate constant. Dehumidification capacities of a DCHE using UiO-66 are estimated via a mathematical model and compared with silica gel- (SG) and LiCl-supported silica gel (SG/LiCl). Simulation results show that UiO-66 has better dehumidification performance than both SG- and SG/LiCl-coated samples for semiarid and semihumid climates when outdoor temperature is lower than 36 °C. Especially, when the temperature and relative pressure of inlet air are set as 30 °C and 0.35, respectively, its dehumidification capacity can be 2.7 times the amount of the SG-coated one and 1.3 times of the SG/LiCl-coated one. However, it should be more prudent in choosing UiO-66 under hot and humid climates.