Physical characteristics analysis and performance comparison of membranes for vacuum membrane dehumidifiers

Abstract The present study pertains to an experimental measurement investigation of membrane physical properties for vacuum membrane dehumidifiers. The membrane material used in an air dehumidification system is a key role for the dehumidification efficiency. To find the most suitable membrane for dehumidification, the membrane physical characteristics are examined by using three critical indexes of air permeance (AP) and water vapor permeance (WP), and selectivity (SE). Two categories of dehumidification membranes, i.e. composite and dense membranes, are applied in the vacuum membrane dehumidifier with a serpentine flow channel. Firstly, the vapor transfer rates of both composite and dense membranes are determined and the experimental data discloses that the composite membranes, such as Sulfone and Metal–organic framework (Mof) membranes, provide higher vapor transport ability, which is not suitable for the vacuum membrane-based dehumidifier. Then, the measurement of AP, WP, and SE is further performed for the dense membranes of Nafion. The result shows that the order of either AP or WP is N.211, N.212, N.115, and N.117, but the SE defined as WP/AP has a different tendency and the order is N.117, N.115, N.212, and N.211. Finally, the results of AP, WP, and SE in this dehumidifier are also compared with the previous experiment.