Modeling of concentration polarization in a reverse osmosis channel with parabolic
Concentration polarization in narrow reverse osmosis channels with parabolic crossflow wasnumerically simulated with difference equations on the permeate velocity, crossflow velocity, average salt concentration, and wall salt concentration. A major new theoretical developmentwas the determination of two correction functions F2 and F3 in the governing equation for theaverage salt concentration. Simulations of concentration polarization under various conditionswere then presented to describe the features of the new model, as well as discussions about thedifferences of concentration polarizations of the more realistic parabolic flow with those whenplug flow or shear flow was assumed. The situations in which the simpler models based on shearor plug flows can be used were indicated. Concentration polarization was also simulated forvarious conditions to show the applicability of the model and the general features ofconcentration polarization in a narrow long reverse osmosis channel.
Keywords: Mathematical modeling; concentration polarization; reverse osmosis; parabolic flow;total salt balance; desalination