3D design of spacer-filled spiral-wound membrane modules

The flow phenomenon through spacer-filled channels depends on geometries: characteristic angle, mesh size, voidage and filament diameter. However, little emphasis has been placed on studying this property and its effect on the performance of the membrane module. In this study, a three-dimensional computational fluid dynamic (3D CFD) technique and an experimental set up with a curved channel filled with a two-layer-filament spacer were used to analyze fluid flow in the channel and the shear stress on the permeable membrane surfaces. This study focused on the influence of the curvature of spacer-filled channels on the pressure drop and shear-stress distributions in spiral-wound membrane modules. Numerical results show that there are inherent changes in the hydrodynamic behavior of the spacer-filled channel due to curvature variations. The increase in curvature of the spacer-filled channel results in an increase in the difference in shear stress between the inner and outer walls. Intuitively conjecture from the simulated numerical results, the imbalance of shear stress between the inner and outer walls may result in an unequal deposition of colloidal material between these two regions and could shorten the service time of the membrane. Microscopic understanding derived from the CFD analysis could improve the construction of a better spacer and module design, which could optimize the filament arrangement and the membrane module performance.