Study of hydrodynamic parameters in the cross-flow filtration of guar gum pseudoplastic solutions

Steady state fluxes obtained during cross-flow filtration of pseudoplastic guar gum solutions are correlated to four hydrodynamic parameters: the cros s-flow velocity, the wall shear stress, the Reynolds number generalised for power law-fluids and wall sheer rate. A mean concentration of the boundary layer at the membrane wall was taken into account to calculate the general ised Reynolds number and wall shear rate. This concentration was identified by fitting the experimental friction factors to the Poiseuille law accordi ng to the method described in [H. Carrere, F. Rene, Exp. Fluids 25 (1998) 2 43-253]. Some parameters of the correlations were expressed as a function o f the mean boundary layer structure index. Description of the hydrodynamic effects on the steady flux was not the same according to the parameter used . The wall shear stress effect was the greatest whereas the shear rate and the generalised Reynolds number effects were the lowest for the more pseudo plastic fluids. The cross-flow velocity effect presented a maximum within t he studied concentration range. (C) 2000 Elsevier Science B.V. All rights r eserved.