Performance study on composite desiccant material coated fin-tube heat exchangers

Abstract

Desiccant coated heat exchanger (DCHE) is a newly developed fin tube heat exchanger with desiccant coating on the surface, it can handle sensible and latent load simultaneously. In this paper, composite desiccant based on silica gel and lithium chloride is adopted as solid adsorbent in DCHE. Equilibrium isotherms of aluminum foils coated with silica gel and composite desiccant are obtained and analyzed through experiment. Further experiment comparison is made between DCHEs coated with these two kinds of desiccant materials. Based on experiment results, a distributed mathematical model of DCHE is established and validated. Then, performance comparison is conducted between silica gel coated heat exchanger (DCHE-S) and silica gel-lithium chloride composite desiccant coated heat exchanger (DCHE-C). Results show that DCHE based on composite desiccant material has higher dehumidification capacity than that based on silica gel, and the advantage is more significant under lower relative humidity. At last, an air-conditioning system based on DCHE is built using the International Building Physics Toolbox (IBPT) and the impact of DCHE air-conditioning system on the indoor environment is examined, it is found that DCHE-C’s performance is close to DCHE-S in handling sensible load but exceeds the latter in processing latent load.