Ali Rasouli

ABSTRACT Theoretical study on extraction of alkali metals using a membrane contactor is carried out in this work. A novel model is built to simulate the flow and the concentration in a membrane extractor based on the finite element analysis. CFD model is applied by solving the 2D Navier–Stokes equations as well as mass conservation equations for steady state conditions in membrane extractors. The model predicts of the velocity field, the pressure and the concentration of alkali metal in the membrane module under laminar flow regime. The results of simulation were used for determination of concentration distribution and effect of extractant concentration on extraction efficiency and mass flux of cesium in the membrane extractor. Moreover, the simulation results for the extraction of cesium using the membrane extractor were compared with the experimental data in order to validate the proposed mass transfer model and showed great agreement.

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 simulation was conducted for physical and chemical absorption of CO2. A mass transfer model was developed to study CO2 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. Moreover, the simulation results were validated with the experimental data obtained from literature for absorption of CO2 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 simulation results indicated that the removal of CO2 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 CO2 separation from gas mixtures.