Effect of wavy corrugations on the performance enhancement of direct contact membrane distillation modules: A numerical study

Abstract

This study employs three-dimensional (3D) computational fluid dynamics (CFD) simulations to investigate the influence of corrugations on direct contact membrane distillation (DCMD) modules. The accuracy of 3D CFD simulations is validated by the comparison of water flux and temperature polarization coefficient (TPC) against literature data for empty and spacer-filled DCMD modules. The dusty gas model is used to predict the permeate flux as a function of temperature and pressure over the surface of the membrane. We consider single and double sinusoidal corrugated membranes and examine the performance of DCMD membranes in terms of TPC, concentration polarization coefficient (CPC), power number (Pn), and Nusselt number (Nu) against various corrugation geometrical parameters. These parameters include the amplitude, streamwise, and spanwise frequency of corrugation waves. Our results show that corrugated membranes can successfully improve the membrane system by disrupting the boundary layer by an intense secondary flow. The mechanism works the best at high flow rates. Our results suggest that singly corrugated membranes improve the water flux and TPC by 32% and 25% at Re=1500. Also, doubly corrugated membranes provide 45% and 36% improvements in water flux and TPC at the same Reynolds number.