Transport Phenomena in a Cross-Flow Hollow Fibre Membrane Bundle Used for Liquid Desiccant Air Dehumidification

The transport phenomena in a hollow fibre membrane bundle for liquid desiccant air dehumidification were investigated. In the bundle, the liquid desiccant solution flows inside the fibres and the process air flows across the fibre bundle; where air is dehumidified by moisture permeation through the membrane. This study investigated the fluid flow and conjugate heat and mass transfer in the cross-flow hollow fibre membrane bundle by considering the interactions between the neighbouring fibres. Two regularly packed arrangements: in-line and staggered, were considered. Due to the periodicity of the fluid flow and heat and mass transfer across the bundle, two representative periodic unit cells, which simultaneously include 2 to 3 neighbouring fibres, were selected as the calculation domains. The equations governing the fluid flow and heat and mass transfer in the two cross-flow streams (solution and air) in the membranes, were solved together with the heat and mass diffusion equations. The friction factor and the Nusselt and Sherwood numbers on both the air and the solution sides were then calculated and experimentally validated. The results were compared to those available data calculated from the free surface model.