Three-Dimensional CFD Analysis of Hydrodynamics and Concentration Polarization in an Industrial RO Feed Channel

Hydrodynamics and mass transfer characteristics in an industrial spiral wound reverse osmosis (RO) feed channel under plant operating conditions are investigated using fully-coupled three-dimensional computational fluid dynamic (CFD) simulations with a detailed spacer geometry. The trend of pressure drop v.s. average longitudinal velocity matches an empirical correlation previously derived from plant data. Different from concentration polarization phenomenon in flat open channels, concentrated islands are isolated in regions near spacer filaments where flow is relatively stagnant. It is shown that concentration polarization may be only a few percent under typical industrial operating conditions. A simplified one-dimensional RO model for control and optimization purposes is developed by incorporating the CFD modeling results.