Moisture transfer characteristics of a LiCl-impregnated paper membrane used for an enthalpy exchanger

In this study, moisture diffusion coefficient of a LiCl-impregnated paper membrane was experimentally obtained through an analysis of heat and moisture transfer of an enthalpy exchanger made with the membrane. A sorption curve was separately obtained by a weighing method. Tests were conducted as a function of relative humidity and temperature. Diffusion coefficient first increases up to 60% relative humidity and then decreases. It also increases with the increase of temperature. The variation of the diffusion coefficient is in the range of 1.8 x 10(-11) m(2)/s to 6.0 x 10(-11) m(2)/s, which is smaller than reported values of hydrophilic polymers. The variation of the moisture permeability, however, is in the range of 2.4 x 10(-7) kg/ms to 1.2 x 10(-6) kg/ms, which is comparable with reported values of hydrophilic polymers. Thus, similar moisture transfer performance is expected between LiCl-impregnated paper and polymer enthalpy exchangers. Possible explanation on the behavior of the diffusion coefficient with relative humidity is provided.