THEORETICAL STUDIES ON MEMBRANE-BASED GAS SEPARATION USING COMPUTATIONAL FLUID DYNAMICS (CFD) OF MASS TRANSFER

Abstract

A 2D mass transfer model was developed to study carbon dioxide removal by absorption in membrane contactors. The model predicts the steady state absorbent and carbon dioxide concentrations in the membrane by solving the conservation equations. The continuity equations for three subdomains of the membrane contactor involving the tube; membrane and shell were obtained and solved by finite element method (FEM). The model was based on “non-wetted mode” in which the gas phase filled the membrane pores. Laminar parabolic velocity profile was used for the liquid flow in the tube side; whereas, the gas flow in the shell side was characterized by Happel’s free surface model. Axial and radial diffusion transport inside the shell, through the membrane, and within the tube side of the contactor was considered in the mass transfer model. The predictions of percent CO₂ removal obtained by modeling were compared with the experimental values obtained from literature. They were the experimental results for CO₂ removal from CO₂/N₂ gas mixture with amines aqueous solutions as the liquid solvent using polypropylene membrane contactor. The modeling predictions were in good agreement with the experimental values for different values of gas and liquid flow rates.