ORIGINAL ARTICLE Separation of CO 2 by single and mixed aqueous amine solvents in membrane contactors: fluid flow and mass transfer modeling Saeed Shirazian • Azam Marjani • Mashallah Rezakazemi Received: 29 March 2011 / Accepted: 21 June 2011 / Published online: 8 July 2011 Ó Springer-Verlag London Limited 2011 Abstract Removal of carbon dioxide from gas mixtures is of vital importance for the control of greenhouse gas emission. This study presents a numerical simulation using computational fluid dynamics of mass and momentum transfer in hollow-fiber membrane contactors. The simu- lation was conducted for physical and chemical absorption of CO 2 . A mass transfer model was developed to study CO 2 transport through hollow-fiber membrane contactors. The model considers axial and radial diffusions in the contactor. It also considers convection in the tube and shell side with chemical reaction. The model equations were solved by numerical method based on finite element method. More- over, the simulation results were validated with the experimental data obtained from literature for absorption of CO 2 in amine aqueous solutions as solvent. The simulation results were in good agreement with the experimental data for different values of gas and liquid velocities. The sim- ulation results indicated that the removal of CO 2 increased with increasing liquid velocity in the tube side. Simulation results also showed that hollow-fiber membrane contactors have a great potential in the area of gas separation specially CO 2 separation from gas mixtures. Keywords Gas separation  Membrane contactor  CFD  Numerical simulation  Mass transfer List of symbols A Cross-section of shell (m 2 ) C 0 Inlet CO 2 concentration (mol/m 3 ) C Concentration (mol/m 3 ) C CO 2 membrane CO 2 concentration in the membrane (mol/m 3 ) C CO 2 shell CO 2 concentration in the shell (mol/m 3 ) C CO 2 tube CO 2 concentration in the tube (mol/m 3 ) C i Concentration of any species (mol/m 3 ) C i-shell Concentration of any species in the shell (m 2 /s) C in Absorbent concentration at the inlet (mol/m 3 ) C inlet Inlet concentration of CO 2 in the shell (mol/m 3 ) C outlet Outlet concentration of CO 2 in the shell (mol/m 3 ) D Diffusion coefficient (m 2 /s) D CO 2 membrane Diffusion coefficient of CO 2 in the membrane (m 2 /s) D CO 2 tube Diffusion coefficient of CO 2 in the tube (m 2 /s) D i-shell Diffusion coefficient of any species in the shell (m 2 /s) J i Diffusive flux of any species (mol/m 2 s) J CO 2 Mass transfer rate of CO 2 (mol/(m 2 s)) k Reaction rate coefficient of CO 2 with absorbent (m 3 /mol s) L Length of the fiber (m) m Physical solubility (–) n Number of fibers P Pressure (Pa) Q shell Gas flow rate (ml/min) Q tube Liquid flow rate (ml/min) r 1 Tube inner radius (m) r 2 Tube outer radius (m) r 3 Shell inner radius (m) r Radial coordinate (m) S. Shirazian  A. Marjani (&)  M. Rezakazemi Department of Chemistry, Islamic Azad University, Arak Branch, Arak, Iran e-mail: a-marjani@iau-arak.ac.ir 123 Engineering with Computers (2012) 28:189–198 DOI 10.1007/s00366-011-0237-7