Analysis of mass transfer in hollow-fiber membranes

The mixing-cup concentration was investigated under different flow conditions (parabolic flow and plug flow in the lumen side of hollow fibers) and at different values of the concentration-dependent diffusion and solute distribution coefficient. The concentration dependency of both coefficients was defined by two different functions and integrated analytically as examples. The mixing cup concentration was calculated by the numerical method. The mixing cup concentration was plotted as a function of an axial coordinate under different conditions.

Variable diffusion and distribution coefficients have a significant effect on the mass transfer in hollow-fiber membranes depending on the values of parameters given the concentration dependency. It was also shown that the flow conditions can also cause essential change in the mixing-cup concentration distribution. The operating conditions and the membrane interface itself have to come closer to the plug flow condi-tions on the lumen side of the cylindrical membrane in order to reach better separation in the hollowfiber membrane or in tube membrane.