Modeling and Simulation of Mass Transfer in Tubular Gas-Liquid Membrane Contactors for Turbulent Flow Conditions and Comparison of Results with Laminar Flow Conditions

CATEGORY: CARBON CAPTURE
Middle-East Journal of Scientific Research 13 (10): 1419-1430, 2013, DOI: 10.5829/idosi.mejsr.2013.13.10.1311
Modeling and Simulation of Mass Transfer in Tubular Gas-Liquid Membrane Contactors for Turbulent Flow Conditions and Comparison of Results with Laminar Flow Conditions
N. Bakhshali, 1 2, R. Tahery and 3, H. Banazadeh
1 Department of Chemical Engineering, Quchan Islamic Azad University, Quchan, Iran
2 Department of Chemical Engineering, Islamic Azad University, Tehran Central Branch, P.O. Box: 1469669191, Tehran, Iran
3Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Abstract:
This study mainly deals with modeling and simulation of turbulent flow conditions in gas absorption by liquid phase in a membrane contactor using computational fluid dynamics (CFD). For this purpose, single tube membrane contactor has been considered. The model has been based on “non-wetted mode”, in which the gas mixture has filled membrane pores, for countercurrent gas-liquid contact. Axial and radial diffusion inside the tube, through the membrane and within the shell side of the membrane contactor have been considered. The simulation results have been compared with those of CO2 absorption in water with laminar flow and similar physical conditions. Both predictions are in qualitative agreement with each other. However, the removal efficiency in turbulent flow conditions is much more than that of laminar flow conditions. It is also indicated that CO2 removal from gas mixture is decreased with increasing gas volumetric flow rate. On the other hand, increasing liquid volumetric flow rate increases the removal efficiency.
Predominant flow regime in hollow fiber and tubular membranes are laminar and turbulent, respectively. Surface area to volume ratio in hollow fiber membrane modules and contactors is more than it of tubular ones. Thus it is interesting to investigate positive effect of turbulent flow conditions in comparison with laminar flow conditions on the removal and separation efficiency in a tubular membrane contactor containing a non-wetted membrane using modeling and simulation for compensating negative effect of its lower surface area to volume ratio. For this purpose, in present work, turbulent flow condition with pretty low Reynolds number is used for the modeling and simulation of physical absorption of CO in a tubular membrane contactor with polytetrafluoroethylene (PTFE) membrane and compared with corresponding laminar flow condition for calculating the removal efficiency difference in two flow regimes.
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