5 - Diffusive Plus Convective Mass Transport Through a Plane Membrane Layer

Abstract

Mass transport in the presence of convective mass flow is significant in order to predict the reaction process. On the other hand, the use of convective flow is rather rare because the aim is mostly to minimize the outlet rate of the reactant on the permeate side. This chapter gives an account of diffusive plus convective mass transport through a plane membrane layer. Convective mass transport takes place if the transmembrane pressure difference exists between two membrane sides. The investigation of the simultaneous effect of the diffusive and convective flows is important when the measures of two flows are comparable with each other. Several membrane processes are involved in the enlargement of the diffusive driving force by the pressure difference between the two sides of the membrane for mass transport, causing convection flow. The presence of convective flow improves the efficiency of the membrane reactor. In theoretical description of mass transport accompanied by zero-order reaction, the effect of the zero-order reaction is discussed for an intrinsically catalytic membrane layer only. Theoretical descriptions of mass transport with variable parameters and asymmetric catalytic membrane are also illustrated.