The Effect of Buoyancy-Driven Convection in Vacuum Membrane Distillation Module

Abstract

CFD simulations were run to determine the impact of buoyancy-driven natural convection on Membrane Distillation, a thermally driven filtration process. A computational domain was created with a high Grashoff number, and vertical and horizontal modules were considered. Convection cells were dominant in the channel at low Reynolds numbers and effectively increased the performance of Membrane Distillation modules by up to 66%. This was done by generating convection cells that reduced the temperature/concentration polarization inside that module, typically forming due to the low Reynolds numbers and correspondingly high thermal and concentration boundary layers. It is shown here that natural convection enhances the flux performance of membrane distillation immensely.