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

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 degrees C. Especially, when the temperature and relative pressure of inlet air are set as 30 degrees 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.

Automated summary

This study introduces a metal-organic framework UiO-66 that achieves excellent water uptake without corrosion, especially in the relative pressure range of 0.35-0.65. Mathematical modeling results indicate that the dehumidification performance of a DCHE using UiO-66 is superior to silica gel (SG) and LiCl-supported silica gel (SG/LiCl) under semiarid and semihumid climates, particularly when outdoor temperature is lower than 36 degrees C.