A CFD Simulation On Spiral Wound Modules For Pervaporation

Pervaporation is one of the most active areas in membrane research because of itscharacteristic of green energy saving. Spiral wound modules make up the shortfall oflow mass flux of pervaporation because of their high packing density. The reliabilityand efficiency of modern numerical methods for obtaining solutions to flow problemshave given rise to the adoption of computational fluid dynamics (CFD) as a widelyused analysis tool for membrane separation systems. CFD could be used in earlydesign of membrane modules incorporating CAD.In spiral wound membrane modules (SWMs), spacers are used to separatemembrane leaves and meanwhile to enhance wall shear stress and to promote eddymixing, thereby reducing wall concentration and fouling. Two-dimensional (2D) andthree-dimensional (3D) CFD models were used in the research to understand how thenet-spacers of SWMs affect the mass transfer. This research would contribute toinitial design of novel net-spacers.2D CFD model was designed to explore methodsfor the simulation which would be applied to the3D model. And also, the2D CFDmodel also was used to validate the data from the simulation. Several3D models weredesigned to analyze how the configurations of net-spacers promote mass transfer bycomparing the differences of the models one and another.Calculations show that proper configurations of net-spacers ensure a high wallshear stress while the Reynolds number is the same. These kinds of configurations canhave a continuous influence on the flow in the channel and reduce the boundary layerand the region of zero flow at the same time. Spacers with holes may help promotepressure losses without decreasing the mass transfer. The pressure loss is a monotonedecreasing function of holes area ratio. Mass transfer refers to the holes area ratiowhile it’s not monotone increasing/decreasing function of holes area ratio. Moduleswith proper holes area ratio produced the highest mass transfer ratio in the research.A simplified model was introduced to the research to qualify the mesh of themodel. Extra mesh for boundary layer was designed for accurate calculation. Thephysical model was simplified to make sure that the flow pattern was the onlyvariable that decides the mass transfer and that the computational work was reduced noticeably.3D surface color map was introduced to the data processing in theresearch.