Experimental investigations of a quasi-counter flow parallel-plate membrane contactor used for air humidification

•A quasi-counter flow parallel-plate membrane contactor (QCFPMC) is proposed for air humidification.•A test rig has been set up to study the performances of the QCFPMC for air humidification.•The performances of the QCFPMC are better than those of the cross-flow one.•The 0.22 μm PVDF membrane contactor has the highest humidification effectiveness.

A quasi-counter flow parallel-plate membrane contactor (QCFPMC) is proposed for air humidification. In the contactor, the liquid water stream is separated from the air stream by membranes, which selectively guarantee the permeation of water vapor while prevent other gases and liquid water from permeating. Therefore the liquid water droplets, which are harmful for indoor air environment, can be avoided. The air and the water streams flow in a quasi-counter flow arrangement. In this paper, a test rig has been set up to study the performances of the QCFPMC employed for air humidification. The air humidification test is conducted under various flowing arrangements, inlet flow rates, temperatures, air humidities, and membrane parameters. The effects of the inlet operation conditions, contactor structures, and membrane parameters on the pressure drop, humidification effectiveness and total mass transfer coefficient are analyzed. It is found that the performances of QCFPMC increase with the increase of water flow rate and temperature. Further, the key role of enhancing the transfer rate of water vapor is played by the water temperature.