A theoretical study was carried out into membrane transport phenomena.Formulae for calculating the membrane transport resistance and transmembrane mass flux were given,variations in membrane resistance and moisture flux with the membrane sorption constant(C)under various humidity conditions were analyzed,and the value of C corresponding to the minimum membrane resistance or the maximum moisture flux was obtained.The results show that the membrane resistance and moisture flux relate not only to C but also to the relative humidities on both sides of the membrane.As C increases,membrane resistance initially decreases but then increases,i.e.,a minimum occurs,while the moisture flux first decreases and then increases,i.e.,a maximum occurs.The membrane resistance and moisture flux reach their extrema at the same value of C,which is determined by the relative humidities on both sides of the membrane.To reduce the membrane resistance,the value of C should be chosen based on the humidity conditions. A theoretical study was carried out into membrane transport phenomena. Formulae for calculating the membrane transport resistance and transmembrane mass flux were given, variations in membrane resistance and moisture flux with the membrane sorption constant (C) under various humidity conditions were analyzed, and the value of C corresponding to the minimum membrane resistance or the maximum moisture flux was. The results show that the membrane resistance and moisture flux relate not only to C but also to the relative humidities on both sides of the membrane. As C increases, membrane resistance initially decreases but then increases, ie, a minimum occurs, while the moisture flux first decreases and then increases, ie, a maximum occurs. membrane resistance and moisture flux reach their extrema at the same value of C, which is determined by the relative humidities on both sides of the membrane. To reduce the membrane resistance, the value of C should be chosen based on the humidity condit ions.