Physical properties measurement and performance analysis of membranes for a multi-stage planar membrane dehumidifier

In this work, the experimental measurement is conducted to examine different membranes to find a suitable option for a planar membrane dehumidifier. The physical properties with critical characteristics of air permeance and water vapor permeance are used as the indexes to evaluate the better membrane applicability for planar dehumidifiers. The experiments contain three parts. Firstly, the air permeance rates of a variety of membranes are measured. Experimental data reveal that Nafion membranes have lower air permeance rate compared with RO membrane under the same degree of vacuum pressure. Secondly, measurements of water vapor permeance of RO and Nafion membranes are carried out. Results show that water vapor permeance of Nafion is better than RO. Finally, Nafion membranes are tested to explore the influence at various temperature, relative humidity and the vacuum side pressure on condensed water and water vapor permeance. The measurement results indicate that increasing temperature enhances the condensed water at either low or high relative humidity, while increasing the pressure on the vacuum side gets less water permeated. As a result, Nafion membranes have characteristics of low air permeance and high water vapor permeance to be candidates of the suitable membrane applied in a planar membrane dehumidifier.