7 - Transport of Fluid Phase in a Capillary Membrane

Abstract

A complete description of a membrane module requires the simultaneous solution of local transport equations that describe the flow and transport conditions. In a capillary membrane module with a permeable membrane wall, three regions of flow should be considered: flow in the lumen, flow within the membrane matrix, and flow in the extracapillary space. Significant simplification is needed to obtain more easily applicable model equations. A structure of the model system with different regions is illustrated. Careful analysis of the separation equipment should be carried out regarding the flow and operating conditions. The pressure distribution in the membrane is determined by application of the overall balance of linear momentum. The utilization of this conservation principle is complicated by the fact that an external force must be applied to keep the polymer membrane stationary. In order to describe the behavior of a membrane module, three submodels are required: two that describe the transport on either side of the membrane and a third model that characterizes the separation properties of the membrane and any porous support material. Equations are provided for flow models for fluid phases on both sides of capillary membrane modules. Special cases of transport models are also discussed.