Effect of random fiber packing on the performance of shell-fed hollow-fiber gas separation modules

A theoretical analysis of the effect of random fiber packing on shell flow distribution, associated shell-side concentration boundary layers, and ultimate performance of shell-fed hollow-fiber gas separation modules is presented. Specifically the relationship between recovery and product oxygen mole fraction is evaluated for nitrogen production from air. Results show that for commercial hollow-fiber membrane modules, random fiber packing is not detrimental to performance relative to the performance of an ideal module. However, poorer performance is predicted for modules with higher permeances. Permeances will have to increase by over an order of magnitude, though, before the effect becomes significant.

Using properties of current commercial modules for nitrogen production from air, performance predictions that account for concentration boundary layers and non-uniform flow in randomly packed fiber bundles are virtually identical to those for an ideal performance model Fig. 4. The effect of oxygen permeance on recovery at a specified product composition for randomly packed bundles. The lines correspond to: solid, xo = 0.0105; dash, xo = 0.0055. The permeance units are kg-mol m!2 Pa!1 s!1.