The Effect of Membrane Topology on Separation Performance of Vacuum Membrane Distillation Module

Abstract

Computational fluid dynamics simulations were conducted to evaluate the effect of a wavy channel in a two-dimensional vacuum membrane distillation module. The curvature was induced using a sinusoidal profile along the membrane and bottom wall. Contour plots and line profiles provide a detailed view of the flow structure and the effect of the proposed configuration on the flux performance. Module averaged temperatures, concentrations, and flux values were calculated for two selected Reynolds numbers. Results indicate that at low Reynolds numbers, the wiggly module performs worse than the flat sheet module. Due to the channel’s curvature changing the direction of the bulk flow and the absence of secondary flows to promote mixing, the thermal boundary layer along the membrane surface can be more intense versus a flat sheet membrane, causing more intense temperature polarization and reduced flux performance. At Reynolds number 500, there was a 5% decrease in the flux for the curved versus flat case. However, in some curved channel areas, the local performance was superior to the flat channel. Increasing the Reynolds number could aid the performance of the wiggly channel immensely.