3D CFD study of hydrodynamics and mass transfer phenomena for spiral wound membrane submerged-type feed spacer with different node geometries and sizes

Modification of the spacer geometry is a promising approach to increase the efficiency of reverse osmosis (RO) spiral wound membrane modules. Column nodes and spherical nodes are considered in this three-dimensional computational fluid dynamic (CFD) study to evaluate the hydrodynamic and mass transfer performance of submerged spacers with different node geometries and sizes. Small-scale CFD analysis results reveal that the column node has better mass transfer performance than the spherical node geometry because column nodes divert more flow to the filaments, leading to higher local velocity at the region between the filament and wall. Furthermore, when the dimensionless node diameter ratio of the column nodes increases from 0.3 to 1.2, Sherwood number and wall shear increase by 25% and 8% respectively at the expense of higher global friction factor (4 4%). A sea water RO full-scale analysis revealed that column node spacers yield higher average flux than spherical nodes and conventional spacers at high feed inlet velocity (> 0.1 m/s), because the mixing effects by the spacer that improve mass transfer are more prominent. (C)& nbsp;2022 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the impact of spacer geometry on the performance of reverse osmosis membrane modules. It finds that column nodes provide better mass transfer efficiency compared to spherical nodes, and increasing the size of column nodes can further enhance the mass transfer and wall shear, albeit at the expense of higher global friction factor. Full-scale analysis shows that column nodes yield higher average flux in sea water reverse osmosis systems at high feed inlet velocity.