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Saeed Shirazian - One of the best experts on this subject based on the ideXlab platform.

  • simulation of co2 absorption by solution of ammonium ionic liquid in hollow fiber Contactors
    Chemical Engineering and Processing, 2016
    Co-Authors: Seyed Mohammad Reza Razavi, Mashallah Rezakazemi, Ahmad B Albadarin, Saeed Shirazian
    Abstract:

    Abstract Membrane-based chemical absorption of CO2 from gas mixtures containing CO2 using tetramethylammonium glycinate solution was studied in this work. The absorption media studied in this work involves a porous membrane contactor which is utilized as a physical barrier for contacting feed gas stream and the chemical solvent. The considered membrane module type was hollow fiber. The equations of concentration for both CO2 and solvent were derived and solved numerically using computational fluid dynamics (CFD) approach. The equations were solved in two dimensions and in cylindrical coordinate, i.e. axial and radial directions in order to obtain the concentration and mass transfer flux of CO2 and solvent in the hollow-fiber contactor. Both convection and diffusional mass transfers were taken into account in the simulations. The findings of CFD simulation demonstrated that as the flow rate as well as the concentration of the absorbent increased, the CO2 removal from gas mixture enhanced; while, the enhancement of gas flow rate declined the removal rate of CO2 in the contactor. The proposed simulation method revealed to be capable of predicting CO2 capture from gas mixtures in membrane Contactors.

  • mathematical modeling and simulation of co2 stripping from monoethanolamine solution using nano porous membrane Contactors
    International Journal of Greenhouse Gas Control, 2013
    Co-Authors: Mehdi Ghadiri, Azam Marjani, Saeed Shirazian
    Abstract:

    Abstract A novel model based on the finite element analysis by COMSOL software is built to simulate the flow and concentration in a membrane contactor for stripping of CO 2 at high operating temperature. A CFD model was developed by solving the 2D Navier–Stokes equations as well as mass conservation equations for steady-state conditions in polymeric membrane Contactors. The model prognosticates the velocity fields and the concentration of CO 2 along the membrane under laminar flow regime. The membrane contactor was divided into three compartments, i.e. tube, shell and microporous membrane. The model findings for the stripping of CO 2 using the membrane contactor were compared with the experimental data in order to validate the proposed mass transfer model and showed great agreement. Moreover, the simulation results showed that mass transfer resistance of gas phase has a minor effect on the CO 2 stripping flux. Increasing temperature and liquid phase velocity cause enhancement of CO 2 stripping flux.

  • modeling and cfd simulation of water desalination using nanoporous membrane Contactors
    Industrial & Engineering Chemistry Research, 2013
    Co-Authors: Mehdi Ghadiri, Safoora Fakhri, Saeed Shirazian
    Abstract:

    A two-dimensional comprehensive model was developed to predict the transport of water in the nanoporous membrane Contactors. The considered membrane distillation device was a counter-current flat-sheet membrane contactor for production of pure water from saline water. The developed model formulates the fundamental transport equations of heat, mass, and momentum in the membrane contactor. The computational fluid dynamics techniques were applied for numerical simulation of model equations. The simulation results were compared with experimental data obtained from literature and showed great agreement with the measured values. A combination of the Knudsen flow and Poiseuille flow was used in the model for estimation of diffusion inside the membrane pores and increased the accuracy of the model. Simulation results revealed that, in the regions adjacent to the membrane wall, the temperature difference is significant. This could be attributed to the fact that a temperature boundary layer is formed near the membr...

  • implementation of the finite element method for simulation of mass transfer in membrane Contactors
    Chemical Engineering & Technology, 2012
    Co-Authors: Saeed Shirazian, Mashallah Rezakazemi, Mahboubeh Pishnamazi, A Nouri, Mostafa Jafari, S Noroozi, Azam Marjani
    Abstract:

    Mathematical modeling and numerical simulation of gas separation by means of polymeric membrane Contactors is presented. The finite element method is implemented for numerical simulation. COMSOL Multiphysics is used for simulation. Continuity equations are solved via computational fluid dynamics techniques based on the finite element method. A laminar velocity profile is applied for the solvent. Velocity distribution of the gas flow in the contactor is obtained by Happel's model. The predictions of percent CO2 removal obtained by the modeling were compared with the experimental values from literature for CO2 removal from CO2/N2 gas mixtures with amines. The modeling predictions were in good agreement with experimental data for different values of liquid flow rates.

  • Separation of CO_2 by single and mixed aqueous amine solvents in membrane Contactors: fluid flow and mass transfer modeling
    Engineering with Computers, 2012
    Co-Authors: Saeed Shirazian, Azam Marjani, Mashallah Rezakazemi
    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 simulation 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. Moreover, 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 simulation 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.

Azam Marjani - One of the best experts on this subject based on the ideXlab platform.

  • mathematical modeling and simulation of co2 stripping from monoethanolamine solution using nano porous membrane Contactors
    International Journal of Greenhouse Gas Control, 2013
    Co-Authors: Mehdi Ghadiri, Azam Marjani, Saeed Shirazian
    Abstract:

    Abstract A novel model based on the finite element analysis by COMSOL software is built to simulate the flow and concentration in a membrane contactor for stripping of CO 2 at high operating temperature. A CFD model was developed by solving the 2D Navier–Stokes equations as well as mass conservation equations for steady-state conditions in polymeric membrane Contactors. The model prognosticates the velocity fields and the concentration of CO 2 along the membrane under laminar flow regime. The membrane contactor was divided into three compartments, i.e. tube, shell and microporous membrane. The model findings for the stripping of CO 2 using the membrane contactor were compared with the experimental data in order to validate the proposed mass transfer model and showed great agreement. Moreover, the simulation results showed that mass transfer resistance of gas phase has a minor effect on the CO 2 stripping flux. Increasing temperature and liquid phase velocity cause enhancement of CO 2 stripping flux.

  • implementation of the finite element method for simulation of mass transfer in membrane Contactors
    Chemical Engineering & Technology, 2012
    Co-Authors: Saeed Shirazian, Mashallah Rezakazemi, Mahboubeh Pishnamazi, A Nouri, Mostafa Jafari, S Noroozi, Azam Marjani
    Abstract:

    Mathematical modeling and numerical simulation of gas separation by means of polymeric membrane Contactors is presented. The finite element method is implemented for numerical simulation. COMSOL Multiphysics is used for simulation. Continuity equations are solved via computational fluid dynamics techniques based on the finite element method. A laminar velocity profile is applied for the solvent. Velocity distribution of the gas flow in the contactor is obtained by Happel's model. The predictions of percent CO2 removal obtained by the modeling were compared with the experimental values from literature for CO2 removal from CO2/N2 gas mixtures with amines. The modeling predictions were in good agreement with experimental data for different values of liquid flow rates.

  • Separation of CO_2 by single and mixed aqueous amine solvents in membrane Contactors: fluid flow and mass transfer modeling
    Engineering with Computers, 2012
    Co-Authors: Saeed Shirazian, Azam Marjani, Mashallah Rezakazemi
    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 simulation 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. Moreover, 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 simulation 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.

  • simulation of heavy metal extraction in membrane Contactors using computational fluid dynamics
    Desalination, 2011
    Co-Authors: Azam Marjani, Saeed Shirazian
    Abstract:

    Abstract A new approach based on momentum and mass transfer for modeling of wastewater treatment was developed in this study. The model is based on solving governing equations for solutes using finite element method (FEM). Wastewater treatment medium considered in this study is a microporous membrane contactor made of polypropylene which is a hydrophobic polymer. Modeling was carried out for separation of water contaminants. With solving conservation equations, velocity and concentration distributions were obtained for the solute in the membrane contactor. Modeling findings showed high removal efficiency for copper extraction. The effect of process parameters on the extraction of copper was investigated. Furthermore, simulation results confirmed that membrane Contactors are efficient in the removal of water contaminants.

  • supercritical extraction of organic solutes from aqueous solutions by means of membrane Contactors cfd simulation
    Desalination, 2011
    Co-Authors: Saeed Shirazian, Azam Marjani, Farzad Fadaei
    Abstract:

    Abstract This work presents mass transfer modeling of solvent extraction by means of membrane Contactors. Model was based on solving conservation equations for solutes in the membrane contactor. The system considered here was a polymeric membrane contactor, an aqueous solution of ethanol or acetone, and a dense solvent. The equations of the model were solved by numerical method using CFD techniques. The simulation results for ethanol and acetone showed an average deviation of 15.6% and 2.5% with the experimental data, respectively. Simulation results indicated that the extraction of acetone is higher than ethanol due to higher solubility of acetone in the solvent. The simulation results revealed that decreasing feed velocity and increasing solvent velocity increase solute removal. The developed mass transfer model is more accurate than other models and represents a general approach for simulation of membrane-based solvent extraction.

Isabelle Souchon - One of the best experts on this subject based on the ideXlab platform.

  • Solvent extraction of highly valuable oxygenated terpenes from lemon essential oil using a polypropylene membrane contactor: potential and limitations
    Flavour and Fragrance Journal, 2011
    Co-Authors: Adeline Dupuy, Violaine Athes, J. Schenk, U. Jenelten, Isabelle Souchon
    Abstract:

    In this study, the technology of membrane Contactors was assessed for the liquid-liquid extraction of highly valuable oxygenated terpenes from lemon essential oil using mixtures of water and ethanol as solvents (20-66% v/v ethanol). The main expected benefit of using membrane Contactors in this application was the elimination of the phase separation step, which can be difficult in these types of systems, which are characterized by a low interfacial tension and the presence of natural surfactants. A commercially available polypropylene hollow fibre contactor (Liqui-Cel (R) 2.5 x 8 with X30 fibres) was used in this study. Stabilizing the interface between the hydro-alcoholic solvent and lemon essential oil in membrane pores proved difficult (breakthrough pressure below 0.2 bar), even with solvents containing only 20% v/v ethanol. This problem was probably due to defects in the membrane material such as the presence of large pores (up to 4 mu m in diameter). Nonetheless, the hydro-alcoholic extract remained emulsion free throughout extraction, considered to be an improvement since it eliminated the time-consuming decantation step (process intensification). High mass transfer coefficients up to 1.08 x 10(-6) m/s were obtained for the tracer of oxygenated terpenes and a solvent with 66% v/v ethanol. The membrane never represented more than 25% of the total resistance to mass transfer. We demonstrated the high potential of using membrane Contactors for this application, provided that improvements were performed on membrane materials. Copyright (C) 2011 John Wiley & Sons, Ltd.

  • Ethanol and aroma compounds transfer study for partial dealcoholization of wine using membrane contactor
    Journal of Membrane Science, 2008
    Co-Authors: Nazely Diban, Violaine Athes, Magali Bes, Isabelle Souchon
    Abstract:

    In the present work viability of membrane Contactors application to partial dealcoholize wines was checked using synthetic wine solutions. A hollow fiber polypropylene (PP) membrane contactor was employed. The process was performed at room temperature and using the most frequent component concentrations present in real wines. The influence of feed and stripping flow rates variation was analyzed. A model considering three resistances in series was developed to predict the ethanol and aroma compounds behavior inside the membrane contactor. Detailed study of the contribution of the individual resistances for ethanol showed that the major contribution to the transport resistance was due to membrane one. The membrane mass transfer coefficient can be calculated using Dusty-gas model expression obtaining a value of . Flavor losses are higher when ethanol content reduction in feed phase increases. Aroma compound losses can reach almost 100% for the most volatile compounds when residence time of the feed stream is larger. A partial dealcoholization of 2% (v/v) gives as a result acceptable aroma losses that do not damage the final perceived quality of the product. A validation on a real wine was performed with an associated sensorial analysis

Lutgarde Raskin - One of the best experts on this subject based on the ideXlab platform.

  • biofilms in full scale drinking water ozone Contactors contribute viable bacteria to ozonated water
    Environmental Science & Technology, 2018
    Co-Authors: Nadine Kotlarz, Nicole Rockey, Terese M. Olson, Sarah-jane Haig, Larry Sanford, John J. Lipuma, Lutgarde Raskin
    Abstract:

    Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone Contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other (p = 0.017). The biofilms downstream of the dead zone contained a significantly (p = 0.036) highe...

  • Biofilms in Full-Scale Drinking Water Ozone Contactors Contribute Viable Bacteria to Ozonated Water
    2018
    Co-Authors: Nadine Kotlarz, Nicole Rockey, Terese M. Olson, Sarah-jane Haig, Larry Sanford, John J. Lipuma, Lutgarde Raskin
    Abstract:

    Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone Contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other (p = 0.017). The biofilms downstream of the dead zone contained a significantly (p = 0.036) higher relative abundance of bacteria of the genera Mycobacterium and Legionella than the upstream biofilms. These results have important implications as the effluent from ozone Contactors is often treated further in biologically active filters and bacteria in ozonated water continuously seed filter microbial communities

Violaine Athes - One of the best experts on this subject based on the ideXlab platform.

  • Solvent extraction of highly valuable oxygenated terpenes from lemon essential oil using a polypropylene membrane contactor: potential and limitations
    Flavour and Fragrance Journal, 2011
    Co-Authors: Adeline Dupuy, Violaine Athes, J. Schenk, U. Jenelten, Isabelle Souchon
    Abstract:

    In this study, the technology of membrane Contactors was assessed for the liquid-liquid extraction of highly valuable oxygenated terpenes from lemon essential oil using mixtures of water and ethanol as solvents (20-66% v/v ethanol). The main expected benefit of using membrane Contactors in this application was the elimination of the phase separation step, which can be difficult in these types of systems, which are characterized by a low interfacial tension and the presence of natural surfactants. A commercially available polypropylene hollow fibre contactor (Liqui-Cel (R) 2.5 x 8 with X30 fibres) was used in this study. Stabilizing the interface between the hydro-alcoholic solvent and lemon essential oil in membrane pores proved difficult (breakthrough pressure below 0.2 bar), even with solvents containing only 20% v/v ethanol. This problem was probably due to defects in the membrane material such as the presence of large pores (up to 4 mu m in diameter). Nonetheless, the hydro-alcoholic extract remained emulsion free throughout extraction, considered to be an improvement since it eliminated the time-consuming decantation step (process intensification). High mass transfer coefficients up to 1.08 x 10(-6) m/s were obtained for the tracer of oxygenated terpenes and a solvent with 66% v/v ethanol. The membrane never represented more than 25% of the total resistance to mass transfer. We demonstrated the high potential of using membrane Contactors for this application, provided that improvements were performed on membrane materials. Copyright (C) 2011 John Wiley & Sons, Ltd.

  • ethanol and aroma compounds transfer study for partial dealcoholization of wine using membrane contactor
    Journal of Membrane Science, 2008
    Co-Authors: Nazely Diba, Violaine Athes, Isabelle Soucho
    Abstract:

    Abstract In the present work viability of membrane Contactors application to partial dealcoholize wines was checked using synthetic wine solutions. A hollow fiber polypropylene (PP) membrane contactor was employed. The process was performed at room temperature and using the most frequent component concentrations present in real wines. The influence of feed and stripping flow rates variation was analyzed. A model considering three resistances in series was developed to predict the ethanol and aroma compounds behavior inside the membrane contactor. Detailed study of the contribution of the individual resistances for ethanol showed that the major contribution to the transport resistance was due to membrane one. The membrane mass transfer coefficient can be calculated using Dusty-gas model expression obtaining a value of K m EtOH = 1.6 × 10 − 4 g P a − 1 m − 2 s − 1 . Flavor losses are higher when ethanol content reduction in feed phase increases. Aroma compound losses can reach almost 100% for the most volatile compounds when residence time of the feed stream is larger. A partial dealcoholization of 2% (v/v) gives as a result acceptable aroma losses that do not damage the final perceived quality of the product. A validation on a real wine was performed with an associated sensorial analysis.

  • Ethanol and aroma compounds transfer study for partial dealcoholization of wine using membrane contactor
    Journal of Membrane Science, 2008
    Co-Authors: Nazely Diban, Violaine Athes, Magali Bes, Isabelle Souchon
    Abstract:

    In the present work viability of membrane Contactors application to partial dealcoholize wines was checked using synthetic wine solutions. A hollow fiber polypropylene (PP) membrane contactor was employed. The process was performed at room temperature and using the most frequent component concentrations present in real wines. The influence of feed and stripping flow rates variation was analyzed. A model considering three resistances in series was developed to predict the ethanol and aroma compounds behavior inside the membrane contactor. Detailed study of the contribution of the individual resistances for ethanol showed that the major contribution to the transport resistance was due to membrane one. The membrane mass transfer coefficient can be calculated using Dusty-gas model expression obtaining a value of . Flavor losses are higher when ethanol content reduction in feed phase increases. Aroma compound losses can reach almost 100% for the most volatile compounds when residence time of the feed stream is larger. A partial dealcoholization of 2% (v/v) gives as a result acceptable aroma losses that do not damage the final perceived quality of the product. A validation on a real wine was performed with an associated sensorial analysis