Membrane porosity and hydrophilic membrane-based dehumidification performance

An experimental study examined the relevance of membrane surface properties to the overall performance of hydrophilic membrane-based dehumidifiers (membrane condensers). Specifically, this study examined a model for the overall mass transfer coefficient derived from surface-science sticking-coefficient arguments, which states that performance is a function of a porosity-weighted average of the surface properties of the bulk membrane material and the surface of the fluid filling the membrane pores. Membranes composed of hydrophilic polyvinylidene fluoride, hydrophilic polyethersulfone, mixed cellulose ester, and 316 stainless steel with porosities between 6 and 80% were used in a flat format for mass transfer measurements in an insulated humid airflow chamber with controlled gas-phase fluid dynamics. While the experiments did not disprove the model, they did not find any meaningful performance differences among the various membrane materials tested, due to membrane surface properties, compared with the gas-side fluid dynamics.