A general description of flows and pressures in hollow fiber membrane modules

Abstract

A coherent description of flow phenomena in hollow fiber membrane devices is given that predicts pressures and flows occuring under various operating modes. The analysis also has relevance to the more general case of laminar or turbulent flow in porous ducts. Flow phenomena in porous ducts have been studied. A general model has been derived that predicts the pressure drop and the magniture and direction of flows in hollow fiber modules for different modes of operation. Only two dimensionless parameters are needed to predict all pressures and flows. One parameter is equal to the ratio of viscous flow resistance in the fibers and the fiber wall permeation resistance whereas the other is related to the entrance flow and its physical properties. The analysis has been carried out for an incompressible pure fluid with laminar or turbulent flow inside the fibers. A constant pressure on the module shell side has been assumed. For the closed-shell mode of operation the laminar-flow model has been extended to include a pressure drop on the shell side. Here a third dimensionless parameter was introduced representing the ratio of viscous flow resistances on the shell and the fiber side.