Experimental study on heat and mass transfer characteristics for a desiccant-coated fin-tube heat exchanger

Abstract

In this study, we investigated the heat and mass transfer characteristics of a desiccant-coated fin-tube heat exchanger (DCHE), in which the desiccant was coated on the surface of a conventional fin-tube heat exchanger. It differs from desiccant wheels in which the desiccant is cooled or heated by the fluid inside the tube during the adsorption or desorption process, and from conventional heat exchangers, in which moisture transfer occurs and the latent heat transfer is caused by phase change of the adsorbed moisture. Firstly, the heat and mass-transfer model for the DCHE was presented in this paper, whereupon the influences of air velocity, desiccant temperature and moisture content on the overall mass-transfer coefficient were separately analyzed for desorption and adsorption processes. It emerged that the overall mass-transfer coefficient rose with increasing air velocity. The moisture content of the desiccant significantly impacted on the overall mass-transfer coefficient. Higher desiccant temperature resulted in lower overall mass-transfer coefficient. Finally, the heat transfer model given in this paper was applied to calculate the DCHE heat transfer rate and the values obtained by calculation were observed to correlate well with the experimental results.