Theoretical and computational analysis on double-end submerged hollow fibre membrane modules

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This paper studies the potential increase in permeate output flow rate that submerged hollow fibres can achieve when operating in double-end suction. The flow dynamics of submerged hollow fibre membranes with different combinations of fibre inner diameter, membrane thickness, and membrane permeability were numerically simulated. Fibre features (fibre inner diameter, membrane thickness, and membrane permeability) are then characterised for their effects on the increment in permeate flow rate due to change in configuration. Concurrently, an analytical model of a fibre in double-end suction is modelled. Analysis on the double-end fibre model has indicated that the fibre characteristic ratio, ?, has a direct influence on the relative increase in output flow rate when both ends are open. Parametric investigations on the three fibre features have shown that their effects on relative output increase agree with the co-relations indicated by ?. For fibres with ? less than 4, a proportional relationship between a fibre's ? value and the percentage increment in permeate flow rate is observed when adopting double-end suction. The fibre characteristic ratio, ?, in addition to characterising flux uniformity, can further be used to consider the effectiveness of applying double-end suction in Submerged Hollow Fibre Membrane Module (SHFMM) systems at the design stage.