On the performance of a plane plate membrane contactor for air dehumidification

ABSTRACT The present paper deals with an experimental and numerical study regarding air dehumidification by means of a hydrophobic membrane contactor and LiCl desiccant solution. The desiccant-membrane systems offer several potential benefits: large working membrane area per unit volume, no carryover of liquid-phase droplets, no pollution of the liquid phase by atmospheric dust, good dehumidification efficiency, potential high-efficiency control of the quality of the handled air. A plane-plate cross-flow contactor, made up of composite PVDF membranes and able to handle air flow rates of about 200 m3/h, has been constructed. The heat and vapour mass transfer between the liquid phase and the process air is analysed. The membrane contactor behaviour has been studied by means of an experimental apparatus. Thermodynamic conditions and flow rates of air and LiCl solution have been measured at the inlet and outlet of the test section. Experiments have been carried out using different air and solution mass flow rates. A computer code able to study the behaviour of the contactor has been developed. Theoretical analysis involves mass and energy equations for both air and liquid desiccant. Moreover, heat and vapour mass fluxes through the membrane have been analysed. Theoretical predictions agree with the experimental data for volumetric air flow rates above 120 m3/h.