Theoretical and experimental studies on isothermal adsorption and desorption characteristics of a desiccant-coated heat exchanger

•Performance of desiccant-coated heat exchangers was experimentally measured.•Isothermal adsorption and desorption experiments were conducted.•Theoretical calculation assumed diffusion of water inside desiccant layer.•Equivalent diffusion coefficient was dependent on the temperature.•Theoretical model could predict experimental results under different conditions. Dynamic characteristics of desiccant–coated heat exchangers (DCHEs) were experimentally measured by wind tunnel. The surface of the DCHE was coated with polymer sorbent desiccant. The isothermal adsorption and desorption experiments were conducted under the condition where the temperatures of the air and brine passing through the DCHE were identical. The experimental results were compared to that obtained from theoretical calculations. A diffusion model predicting the distribution of moisture concentration and temperature in the desiccant layer was introduced. The equivalent diffusion coefficient of the water inside the desiccant layer was determined from the experimental results. The adsorption and desorption speeds were at the maximum values at the beginning of the sorption processes, and then they gradually decreased. The equivalent diffusion coefficient was dependent on the temperature. Assuming the temperature dependence of the diffusion coefficient, the calculated sorption performance correlated well with that obtained from the experimental results.