Separate Expression of Polarization Modulus and Enrichment by Mass Transport Parameters for Membrane Gas Separation

Abstract

Several membrane processes involve the convective velocity in the boundary layer due to high solubility and diffusivity in the membrane. The relatively high value of the convective velocity, as it can exist during gas separation, can cause convex concentration distribution in the boundary layer, and consequently, it can alter the diffusive flow throughout the boundary layer, as well. How the Peclet number affects the diffusive flow is discussed in the first part of this study. It has been stated when the Pe > about 0.3–0.5, the diffusive mass transfer coefficient of the boundary layer obtained by prediction using dimensionless quantities, should be corrected by a factor depending on the Peclet number, obtained by the exact solution of the boundary layer’s concentration distribution. The curvature effect of the concentration distribution is then taken into account by this factor. In the second part of this study, the polarization modulus and enrichment are separately expressed by means of the mass transpor...