The effects of membrane and channel corrugations in forward osmosis membrane modules - Numerical analyses

Computational fluid dynamics simulations were used to model the effects of the membrane and channel corrugation in forward osmosis desalination systems. The modified solution-diffusion model was used to predict the water flux through the membrane by including the effect of the porous support layer. The flux model couples the concentration of the feed and draw solution to predict the water permeation rate. The distribution of the water flux, concentrative and dilutive concentration polarization and shear stress were monitored over the surface of the membrane. The laminar model was used in the module with no corrugation, and k - omega SST turbulence model was used in modules consisting of corrugations for Re = 300, 800 and 1500. The flux model was validated quantitatively against existing experimental work with membrane systems containing net-type spacers. The results indicate that single membrane corrugation and channel corrugation are more effective in mitigating the external concentrative and dilutive concentration polarizations and alleviating the potential scaling and fouling than the double and combined membrane corrugations. Nearly 15% increase in water permeation rate was obtained with the combined corrugation case. The coefficient of performance suggests that the single and double corrugation cases at Re = 300 had the best performance.