Analysis of concentration polarization phenomenon in ultrafiltration under turbulent flow conditions

An ultrafiltration data set previously reported by Gekas and Olund is used to test three concentration polarization models. The data consist of testing eight ultrafiltration membranes representing different polymer materials and molecular weight cut-offs with 0.5 wt% Dextran T10 at 25 degrees C and 0.5 MPa under turbulent flow conditions. The tested concentration polarization models include the modified film theory model, the original film theory model and the Sherwood correlation model. The Chilton-Colburn analogy is the common foundation of the these models. The modified film theory model appears to provide a reasonable estimate for the actual rejection and solute concentrations adjacent to the membrane surface. Furthermore, the modified film theory model relates the convective and diffusion mechanisms in terms of their mass transfer coefficients (K-F and K-m) in one model. Consequently, the modified film theory model eliminates the need for an external solute rejection mechanism to compliment a concentration polarization model.