Document Type: Research Paper
Department of Chemical Engineering, Faculty of Engineering, Arak University, Arak 38156-8-8349, Iran
Department of Petroleum and Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
In this study, a time-dependent 2D axisymmetric model of a multilayer hollow fiber composite membrane for gas separation is proposed. In spite of the common multilayer membranes, which a dense layer coated on a porous support layer and subjected into the feed stream, here, the porous support is exposed to the feed gas. In this regard, the governing equations of species transport are developed for model domains and then solved by a finite element method (FEM). Gas permeation properties of pure H2 , O2 , N2 , CH4 , CO2 and He are calculated and validated with experimental data with good conformity. Obtained results indicate that with increasing the temperature, the permeability and diffusion coefficient increased while the solubility decreased. Moreover, the permeability and solubility variations with temperature for a heavier gas, CO2 , were higher than those for the lighter ones, while the diffusion coefficient variation with temperature for the lither gas, such as He, was more than the heavier ones. By increasing the CO2 feed stream temperature from 25 to 75°C, its permeability and diffusion coefficient increased respectively from 245 to 307 Barrer and from 205 to 282×10-12 m2 /s, while the CO2 solubility decreased from 0.85 to 0.76 cm3.cm3.bar1. In the case of He and for the same temperature variation range, its permeability and diffusion coefficient increased respectively from 39 to 42 Barrer and from 2180 to 2834 10-12 m2 /s, while the solubility of He decreased from 0.013 to 0.011 cm3 .cm-3.bar-1.