A 3-dimentinal CFD model for simulation of an O2/N2 separation process using an industrial PIHF membrane module for N2 enrichment

Abstract

In this research, simulation of an O2/N2 membrane separation process for N2 enrichment using an industrial polyimide hollow fiber (PIHF) membrane module was performed based on finite element method. A 3-dimensional (3D) model was used to simulate the mass transfer, convection and diffusion phenomenon in the membrane module. In order to validate the model, the simulation results were compared with the industrial process data, and good agreement was observed. The effects of feed molar flow rate, feed pressure, and molar flow rate of sweep gas stream on the N2 enrichment percentage were investigated. As discovered, the N2 enrichment percentage is improved by enhancing the feed pressure and sweep gas flow rate, while an increase in feed flow rate promotes a diminish in percentage of N2 enrichment. Besides the operational parameters, the influence of flow patterns (co-current and counter-current) and fiber length on the N2 enrichment in lumen side and gas molecules distribution in the membrane side of PIHF membrane module was investigated respectively. As the fiber length increased, the N2 enrichment percentage augments for both patterns due to membrane surface area increment in the PIHF membrane module, which the percentage of N2 enrichment in the countercurrent pattern was higher than co-current. Moreover, Concentration Polarization Index (CPI) was investigated to show the degree of polarization expansion along the PIHF membrane. The effect of feed molar flow rate on the concentration polarization index was investigated, which showed that concentration polarization phenomenon is reduced when feed molar flow rate enhances.