Flow and mass transfer modelling of nanofiltration

A numerical model based on the finite volume formulation to predict laminar flows hydrodynamics and mass transfer of aqueous solutions (570 < Sc < 320 0) in the feed channel of spiral-wound and plate-and-frame systems is prese nted and experimentally validated. Particular attention is devoted to the p hysical modelling of the solute transport inside the membrane that yields p arameters pertaining to solute-membrane interactions and are incorporated o n the mass transfer boundary condition at the membrane surface. A correctio n factor, dependent on the solute mass concentration at the membrane surfac e, is proposed for the osmotic pressure phenomenological equation. The expe rimental cell is a slit (200 mm x 30 mm x 2 mm) that simulates the two-dime nsional developing flow in the channels of spiral-wound modules. The predic tions are validated against experimental data of apparent rejection coeffic ients and permeate fluxes, exhibiting an excellent agreement. A correlation for the concentration boundary layer thickness, a measure of the concentra tion polarisation, based on the predicted values of the solute concentratio n profiles, delta (omega)/h = 15.5 (l/h)(0.4) Re-0.4Sc-0.63 Re-p(-0.04)[1-186Sc(-1.0)Re (p)(-0.21)] is proposed in the operating condition ranges of 250 < Re < 1000, 0.02 < Re -p < 0.1 and 800 < Sc < 3200. (C) 2001 Elsevier Science B.V. All rights res erved.