Comparative study on the water uptake kinetics and dehumidification performance of silica gel and aluminophosphate zeolites coatings

Desiccant coated heat exchanger (DCHE) systems have significant potential in improving dehumidification performance. The moisture transfer occurring in one single air channel of DCHE can dominate the overall system performance. In this study, the adsorber with an approximate air channel of DCHE was designed to experimentally investigate the kinetics of silica gel and two aluminophosphate zeolites (FAM Z01 and FAM Z05). Their dehumidification performances also were simulated at regeneration temperature range of 50-80 degrees C to reveal the applicability in air-cooled cross-flow DCHE. Results showed that linear driving force (LDF) model could well describe the dynamic water uptake behaviors. Adsorption rate coefficient k(ads) increased with increasing inlet air humidity ratio and velocity, but decreased with increasing coating thickness. It is worth noting that increasing regeneration temperature had a little effect on k(ads), while desorption rate coefficient k(des) increased significantly. Simulation results showed that moisture removal capacity (MRC) and dehumidification coefficient of performance (DCOP) of FAM Z05 coated DCHE could reach 0.495 g/kg and 0.57 at regeneration temperature of 50 degrees C, which were 2.3 and 15.4 times higher than these of silica gel and FAM Z01 coated DCHEs. It demonstrated that FAM Z05 was more promising to utilize lower-grade heat energy. (C) 2021 Elsevier Ltd. All rights reserved.