The effect of mixing promotors on sweeping gas membrane distillation system performance

Computational fluid dynamics simulations were conducted to model the effect of adding mixing promoters in sweeping gas membrane distillation modules. Net-type spacers of 45° are placed in the feed side while membrane corrugation is employed with the tips of the corrugation pointing towards the permeate side. The membrane corrugation is of chevron type. The membrane is considered as a functional surface, and the vapor flux through the membrane is modeled using the Dusty-Gas model. The vapor flux equation couples the vapor pressure variation across the membrane with the feed concentration. The flow inside the channels with mixing promoters is considered turbulent. The k − ω SST turbulent model is used to model the steady-state turbulent structures inside the channels. The flow rate in the feed side is fixed, and the flow rate in the permeate channel is varied so that Re_p = 1000, 1500, and 2000 are considered. The inlet feed and permeate temperatures, and the membrane properties are fixed. The results indicate that the presence of mixing promoters increases the vapor permeation through the membrane by alleviation of the concentration and temperature polarization effects. The mixing promoters are more effective at high flow rates in both channels.