Analysis and simulation of the coupled mass and heat transfer in the process of moisture exchange across a membrane

The coupled mass and heat transfer in moisture exchange across a membrane was analyzed theoretically and the corresponding physical and mathematical model was established. A method was developed to calculate this coupling process. The result supports that the impacts of mass transfer on heat transfer show in two respects: one is that of the enthalpy carried by the flow and the other is that of the heat of adsorption, while the impact of heat transfer on mass transfer results from the impact of temperature on moisture resistance in membrane. The coupling process was simulated numerically and the results suggest that: in the case that the heat and mass transfer are in the same direction, the thermal resistance increases with increases the humidity difference, while in the case that the heat and mass transfer are in the opposite directions, the thermal resistance decreases with increasing the humidity difference. The effect of the humidity difference on the moisture resistance is negligible. A higher temperature will lead to a larger mass flow rate and a lower moisture resistance, which will influence the heat flux and thermal resistance.