This model calculates the locally distributed mass transfer through a thin membrane. The model is based on the Solution-Diffusion model. It uses the permeability to describe the process of sorption, diffusion and desorption of the water vapour. For detailed information see [1].
[1]: Koester, S.; Roghmans, F.; Wessling, M.: Water vapor permeance: The interplay of feed and permeate activity ; Journal of Membrane Science; Vol. 485 (2015) pp. 69-78