The Experts below are selected from a list of 2475 Experts worldwide ranked by ideXlab platform

Sharad Kumar Gupta - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of a forward osmosis and a pressure-retarded osmosis spiral wound Module using the Spiegler-Kedem model and experimental validation
    Separation and Purification Technology, 2016
    Co-Authors: Dinesh Attarde, Manish Jain, Sharad Kumar Gupta
    Abstract:

    Abstract A mathematical model is developed for a spiral wound Module for both forward osmosis (FO) and pressure-retarded osmosis (PRO) applications. This model is obtained by combining the membrane transport, external concentration polarization, and internal concentration polarization models with the pressure drop and mass balance equations for both the feed as well as the draw solutions. The Spiegler-Kedem (SK) model is used for describing the local mass transport in the active layer of the membrane. In addition, a new expression is established for determining the internal concentration polarization in the support layer of the membrane. A nonlinear constrained optimization technique is then applied, along with the experimental data for FO and PRO, to predict the unknown parameters of the mathematical model for the spiral wound Module. To ensure the validity of the proposed model and predicted parameters, the model is again used to predict and compare the performance of the Module at a variety of operating conditions. Apart from this, the product recovery and the energy extraction efficiency of the Module at a variety of operating conditions are also analyzed. Lastly, we have tried to answer the question, whether the Solution Diffusion (SD) based model or the SK based model is better for design and analysis, and for obtaining the optimal operating conditions for both FO as well as PRO applications.

  • Influence of hydrocarbon species on the removal of thiophene from FCC gasoline by using a spiral wound pervaporation Module
    Journal of Membrane Science, 2016
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    Pervaporation is an emerging technology in the field of thiophene removal from the Fluid Catalytic Cracker (FCC) gasoline. The performance of pervaporation process for thiophene removal depends on different types of hydrocarbon species present in the FCC gasoline due to their distinctive transport properties in the membrane, as well as due to their distinct physical and thermal properties. In membrane Modules, the presence of different hydrocarbon species may also affect the variations in flow variables such as the temperature and concentrations in the feed and permeate channels. This in turn may further influence the performance of the Module. The present study shows how different hydrocarbon species present in the gasoline influence the performance of a spiral wound Module. First, the experimental data for a number of binary mixtures are obtained for a variety of hydrocarbons and thiophene. This data is then analysed by using a mathematical model for the spiral wound Module. The membrane transport parameters are determined by using a parameter estimation technique. The results indicate that the thiophene (C4H4S) removal from different binary mixtures may be sorted out based on the type of hydrocarbon species present in the binary mixtures as linear alkane>alkene>branched alkane>aromatic compounds. Results for a ternary mixture show that the same mathematical model may also be used for predictions of the Module performance by assuming the ternary mixture to be equivalent to a binary mixture of two species: first is thiophene, and second species is a pseudo-species, having the average physical properties of two other hydrocarbons present in the ternary mixture. The same approach may be extended to a multicomponent feed of a real FCC gasoline, containing a variety of hydrocarbons and sulphur containing compounds. This approach may provide sufficiently accurate predictions with much lesser efforts in comparison to more rigorous, and much more tedious, multicomponent modelling.

  • Osmotically driven membrane processes by using a spiral wound Module - modeling, experimentation and numerical parameter estimation.
    Desalination, 2015
    Co-Authors: Dinesh Attarde, Manish Jain, Kshitij Chaudhary, Sharad Kumar Gupta
    Abstract:

    Abstract Pressure retarded osmosis (PRO) and forward osmosis (FO) are osmotically driven membrane processes and emerging as viable methods for capturing clean energy and producing fresh water from sea water, respectively. The critical problems restricting the application of these processes are the accurate design and analysis of the membrane Module or Module configurations. Hence, a mathematical model is obtained to predict the performance of a spiral wound membrane Module for osmotically driven membrane processes. Transport phenomena through the membrane are described by the previously proposed solution diffusion based model. In the current work, this model is coupled with the differential mass balances on the feed and permeate sides of the Module. In addition, the Darcy's theory is used in the model to incorporate the pressure drop in the channels of Module. The finite difference method is employed to solve coupled algebraic and ordinary differential equations. Here, we also employ a combination of two optimization techniques (Univariate and Fibonacci three point methods) with laboratory scale experimental data points to estimate the unknown parameters of the model. These estimated parameters are then used to predict the performance of FO and PRO at some other operating conditions and validate the mathematical model. Relatively lower maximum power density is observed at a lower draw side hydraulic pressure in the spiral wound Module as compared to power density in a membrane test cell. The experimental results obtained by this Module matched well with the model predictions.

  • Removal of thiophene from n-heptane/thiophene mixtures by spiral wound pervaporation Module: Modelling, validation and influence of operating conditions
    Journal of Membrane Science, 2015
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    In recent years, pervaporation has been investigated rigorously for separation of thiophene and its derivatives from the fluid catalytic cracker (FCC) gasoline. Like other membrane-based processes, the scale up and commercialization of this process require the study of the separation performance at the membrane Module scale. In this study, a suitable mathematical model is obtained to predict the performance of a spiral wound pervaporative Module for the removal of thiophene from n-heptane/thiophene mixtures. The experiments were performed on a Polydimethylsiloxane (PDMS) based spiral wound Module for a variety of operating conditions. The model predictions showed good agreement with the experiment results. Results indicate that the Module performance may be improved with higher permeate pressures and the lower feed temperatures. However, this trend may not be universal and may be altered for some different feed systems or membranes, which shows the necessity to analyse every feed system and membrane material for determining the optimum operating conditions. Simulations also demonstrated that the variations in flow variables along the feed and permeate channels may also have profound effects on the Module performances. Finally, the performance of a pervaporation process was simulated by using a number of spiral wound Modules in series, which demonstrated that the pervaporation might successfully remove thiophene from FCC gasoline up to any desired limit.

Maria Norberta De Pinho - One of the best experts on this subject based on the ideXlab platform.

  • Spiral-Wound Module Nanofiltration of Surface River Water
    2008
    Co-Authors: Vitor Geraldes, Maria Norberta De Pinho, Carlos Manuel Simões Fonseca, Elizabeth Duarte
    Abstract:

    The performance of the nanofiltration of surface water, using a Spiral-Wound Module, was accessed for the particular case of the Tagus River surface water collected at ca. 40 km of Lisbon (Portugal). The nanofiltration experiments were performed in the nanofiltration laboratory unit with a spiral wound Module with 2.6 m 2 of membrane area (Filmtec NF2702540, DOW Chemical), for different transmembrane pressures, recirculation flow rates and water recovery rates. The permeate flux and the rejection coefficients of total organic carbon (TOC), adsorbable organic halogens (AOX) and inorganic ions were measured. The rejection coefficient of bivalent ions was in the range of 80-98% and for monovalent ions was in the range of 20-70%. The rejection coefficient increases with the transmembrane pressure and is not dependent on the water recovery rate, for the range of operating conditions investigated. The recirculation flow rate had almost no effect on the rejection coefficient of the ions, indicating that the concentration polarization was not severe. The NF process has a rejection of TOC higher than 80%, contributing to reduce strongly the formation of disinfection by-products precursors. The process is also adequate to remove partially the AOX from the surface water. Depending on the operating conditions, the rejection coefficient of AOX was in the range between 26% and 72% for transmembrane pressures higher than 400 kPa.

  • Dissolved air flotation of surface water for Spiral-Wound Module nanofiltration pre-treatment
    Desalination, 2008
    Co-Authors: Vitor Geraldes, Maria Norberta De Pinho, Aykut Anil, Elizabeth Duarte
    Abstract:

    Abstract Bench-scale dissolved air flotation (DAF) of Tagus River surface water (Valadas, Portugal) was investigated as pre-treatment for Spiral-Wound Module nanofiltration (SWNF). Before the DAF, a coagulation/flocculation of the surface water was performed using aluminium sulphate, ferric chloride and chitosan coagulants and several commercial coagulant aids. The coagulation/flocculation experiments were carried with 2 L of surface water in a jar-test equipment at room temperature. The DAF performance to remove colloidal matter and suspended solids was evaluated through the measurement of the silt density index (SDI) and the modified fouling index (MFI) of the treated water. The air saturation pressure was varied between 300 and 600 kPa and the recycle ratio between 5 and 50%. The DAF without coagulation/flocculation was not effective in the reduction of both the SDI and MFI, even at a high DAF recycle ratio of 50%. The use of coagulants improved the DAF efficacy in reducing the fouling indexes and, for the optimal operating conditions, the MFI of the treated water was reduced by more than one order of magnitude. However, it was not possible to obtain treated water with SDI and MFI values below the recommended ones for SWNF. Further filtration of the DAF treated water with a 5 micron capsule filter was necessary to reduce the SDI below 5%/min and the MFI below 10 s/l 2 . The integration of DAF with another process that removes the residual suspended solids and colloidal matter is, therefore, necessary to provide a good pretreatment for the SWNF of Tagus River surface water.

  • Hydrodynamics and concentration polarization in NF/RO Spiral-Wound Modules with ladder-type spacers
    Desalination, 2003
    Co-Authors: Vitor Geraldes, Viriato Semiao, Maria Norberta De Pinho
    Abstract:

    Abstract The hydrodynamics and concentration polarization in the feed-channel of a NFIRO Spiral-Wound Module with ladder-type spacers were investigated by computational fluid dynamics. The momentum and mass transport equations together with the appropriate boundary conditions were solved numerically by the control volume formulation for stable two-dimensional laminar flow. Permeation experiments with aqueous solutions of sodium chloride at feed concentration of 2 gll and 25°C were performed in a laboratory NF cell with a spacer-filled channel (2 mm height × 30 min width × 20 cm length) in order to validate the numerical model. The tested spacer had a set of transverse filaments with a diameter of 1.0 mm, equally spaced and connected by two longitudinal filaments, with a distance between the axis oftwo consecutive filaments of 3.8 mm, forming a ladder-type structure. A thin-film composite nanofiltration membrane from Separem (Italy) was used. The numerical results show that the concentration polarization index exhibits strong local variations, and its profile is correlated with the flow pattern. It was also found that the increase of the Reynolds number is not by itself a sufficient condition to enhance the hydrodynamic conditions over the whole membrane: an adequate control of the flow structure through the careful selection of the cross section of the filaments is also indispensable. Good agreement was observed between the predicted and experimental values of the apparent rejection coefficient for all the range of operating conditions tested.

  • flow management in nanofiltration spiral wound Modules with ladder type spacers
    Journal of Membrane Science, 2002
    Co-Authors: Vitor Geraldes, Viriato Semiao, Maria Norberta De Pinho
    Abstract:

    Abstract The incompressible laminar and two-dimensional flow in narrow rectangular channels filled with ladder-type spacers that have the transverse filaments adjacent to a semi-permeable wall, was investigated in order to have insight on the feed flow in a nanofiltration (NF)/reverse osmosis (RO) spiral wound Module. The study was based on numerical simulations and on experiments of flow visualisation with tracer injection and pressure drop measurements. The numerical simulations were performed assuming fully developed laminar flow quasi-periodically repeating in successive inter-filament regions. Ladder-type spacers with inter-filament distances/channel height ratios ( L f ) of 1.9, 3.8 and 5.7 were investigated. The ratio ( P f ) between the transverse filaments height and channel height was investigated between 0.25 and 0.75 in the numerical study and was fixed to 0.5 in the experiments. Flow visualisation with tracer injection and friction factor measurements were made for the water flow in a spacer-filled rectangular channel with 2 mm height, 30 mm wide and 200 mm long, in the range of Reynolds numbers (based on the channel height and on the average inlet velocity) between 50 and 1000. These results show that for increasing inter-filament distances the transition critical Reynolds number decreases from 300 to 150. Below this critical value, the flow is observed to be laminar and two-dimensional. The numerical simulations show that the flow structures are associated to the occurrence of recirculation zones downstream each transverse filament. For low values of the Reynolds number and P f and high values of L f , the recirculation region does not reach the second filament, while for high values of the Reynolds number and P f and low values of L f the recirculation region extends from the first to the second filament. Additionally, for P f =0.75, a secondary recirculation region can be formed inside the main recirculation region. Each of these situations is associated to different patterns of concentration boundary layers growth and subsequently different solute concentration distributions at the membrane surface.

  • The effect of the ladder-type spacers configuration in NF Spiral-Wound Modules on the concentration boundary layers disruption☆
    Desalination, 2002
    Co-Authors: Vitor Geraldes, Viriato Semiao, Maria Norberta De Pinho
    Abstract:

    Abstract The laminar flow structure and concentration distribution in a narrow rectangular channel simulating the feed channel of nanofiltration (NF) Spiral-Wound Modules are investigated. The continuity, Navier—Stokes equations and the solute continuity equation are solved by the control volume formulation. To validate the numerical predictions, NF permeation experiments with an aqueous solution of sodium chloride (2 g/l) at 25°C were performed in a laboratory cell with a rectangular feed channel (2 mm height × 30 mm width × 20 cm length) filled with a ladder-type spacer with a transverse inter-filament distance of 3.8 mm. The numerical results show that the average concentration polarization for the membrane wall with adjacent transverse filaments is independent of the distance to the channel inlet, while for the membrane wall without adjacent filaments the average concentration polarization increases with the channel length. This is due to the fact that in the first case the concentration boundary layer is periodically disrupted by the transverse filaments while in the second case the concentration boundary layer grows continuously along the channel length. The experimental results of the NaCl apparent rejection coefficients are compared to the model predictions, the agreement being good. These results clearly establish how crucial the spacers configuration is in the optimization of the spiral wound Module efficiency.

Vitor Geraldes - One of the best experts on this subject based on the ideXlab platform.

  • Spiral-Wound Module Nanofiltration of Surface River Water
    2008
    Co-Authors: Vitor Geraldes, Maria Norberta De Pinho, Carlos Manuel Simões Fonseca, Elizabeth Duarte
    Abstract:

    The performance of the nanofiltration of surface water, using a Spiral-Wound Module, was accessed for the particular case of the Tagus River surface water collected at ca. 40 km of Lisbon (Portugal). The nanofiltration experiments were performed in the nanofiltration laboratory unit with a spiral wound Module with 2.6 m 2 of membrane area (Filmtec NF2702540, DOW Chemical), for different transmembrane pressures, recirculation flow rates and water recovery rates. The permeate flux and the rejection coefficients of total organic carbon (TOC), adsorbable organic halogens (AOX) and inorganic ions were measured. The rejection coefficient of bivalent ions was in the range of 80-98% and for monovalent ions was in the range of 20-70%. The rejection coefficient increases with the transmembrane pressure and is not dependent on the water recovery rate, for the range of operating conditions investigated. The recirculation flow rate had almost no effect on the rejection coefficient of the ions, indicating that the concentration polarization was not severe. The NF process has a rejection of TOC higher than 80%, contributing to reduce strongly the formation of disinfection by-products precursors. The process is also adequate to remove partially the AOX from the surface water. Depending on the operating conditions, the rejection coefficient of AOX was in the range between 26% and 72% for transmembrane pressures higher than 400 kPa.

  • Dissolved air flotation of surface water for Spiral-Wound Module nanofiltration pre-treatment
    Desalination, 2008
    Co-Authors: Vitor Geraldes, Maria Norberta De Pinho, Aykut Anil, Elizabeth Duarte
    Abstract:

    Abstract Bench-scale dissolved air flotation (DAF) of Tagus River surface water (Valadas, Portugal) was investigated as pre-treatment for Spiral-Wound Module nanofiltration (SWNF). Before the DAF, a coagulation/flocculation of the surface water was performed using aluminium sulphate, ferric chloride and chitosan coagulants and several commercial coagulant aids. The coagulation/flocculation experiments were carried with 2 L of surface water in a jar-test equipment at room temperature. The DAF performance to remove colloidal matter and suspended solids was evaluated through the measurement of the silt density index (SDI) and the modified fouling index (MFI) of the treated water. The air saturation pressure was varied between 300 and 600 kPa and the recycle ratio between 5 and 50%. The DAF without coagulation/flocculation was not effective in the reduction of both the SDI and MFI, even at a high DAF recycle ratio of 50%. The use of coagulants improved the DAF efficacy in reducing the fouling indexes and, for the optimal operating conditions, the MFI of the treated water was reduced by more than one order of magnitude. However, it was not possible to obtain treated water with SDI and MFI values below the recommended ones for SWNF. Further filtration of the DAF treated water with a 5 micron capsule filter was necessary to reduce the SDI below 5%/min and the MFI below 10 s/l 2 . The integration of DAF with another process that removes the residual suspended solids and colloidal matter is, therefore, necessary to provide a good pretreatment for the SWNF of Tagus River surface water.

  • Optimization of ladder-type spacers for nanofiltration and reverse osmosis Spiral-Wound Modules by computational fluid dynamics
    Computer Aided Chemical Engineering, 2004
    Co-Authors: Vitor Geraldes, Viriato Semiao, Norberta De Pinho
    Abstract:

    The velocity and solute concentration disitribution in the feed channel of a spiral wound Module with ladder-type spacers is investigated by computational fluid dynamics (CFD) for laminar flow and permeation of sucrose aqueous solution. The spiral wound Module feed channel was approximated by a rectangular channel filled with ladder-type spacers that have the transverse filaments adjacent to a single membrane wall. The momentum and mass transport equations together with the appropriate boundary conditions are solved numerically by the control volume formulation. The numerical predictions were performed for Reynolds numbers of Re = 50, 100 and 200, Pf ≡ pjh = 0.25, 0.5 and 0.75 and Lf≡ lf/h = 1.9, 3.8 and 5.7 — where h is the channel height, pf is the transverse filament height and lf is the distance between neighbor filaments axis. The numerical results show that the flow is dominated by a recirculation region downstream of each transverse filament and that there are no recirculation regions in the upper part of the channel. Three flow structures were identified: for low values of Re and Pf and high values of Lf the recirculation region does not fill the inter-filaments space; for high values of Re and Pfand low values of Lf the recirculation regions fills the inter-filaments space; and for Pf = 0.75, a secondary recirculation region can develop inside the main one. The numerical results show that the spacer optimal values of Pf = 0.25 and Lf= 5.7 minimize both the concentration polarization and the longitudinal pressure drop.

  • Hydrodynamics and concentration polarization in NF/RO Spiral-Wound Modules with ladder-type spacers
    Desalination, 2003
    Co-Authors: Vitor Geraldes, Viriato Semiao, Maria Norberta De Pinho
    Abstract:

    Abstract The hydrodynamics and concentration polarization in the feed-channel of a NFIRO Spiral-Wound Module with ladder-type spacers were investigated by computational fluid dynamics. The momentum and mass transport equations together with the appropriate boundary conditions were solved numerically by the control volume formulation for stable two-dimensional laminar flow. Permeation experiments with aqueous solutions of sodium chloride at feed concentration of 2 gll and 25°C were performed in a laboratory NF cell with a spacer-filled channel (2 mm height × 30 min width × 20 cm length) in order to validate the numerical model. The tested spacer had a set of transverse filaments with a diameter of 1.0 mm, equally spaced and connected by two longitudinal filaments, with a distance between the axis oftwo consecutive filaments of 3.8 mm, forming a ladder-type structure. A thin-film composite nanofiltration membrane from Separem (Italy) was used. The numerical results show that the concentration polarization index exhibits strong local variations, and its profile is correlated with the flow pattern. It was also found that the increase of the Reynolds number is not by itself a sufficient condition to enhance the hydrodynamic conditions over the whole membrane: an adequate control of the flow structure through the careful selection of the cross section of the filaments is also indispensable. Good agreement was observed between the predicted and experimental values of the apparent rejection coefficient for all the range of operating conditions tested.

  • flow management in nanofiltration spiral wound Modules with ladder type spacers
    Journal of Membrane Science, 2002
    Co-Authors: Vitor Geraldes, Viriato Semiao, Maria Norberta De Pinho
    Abstract:

    Abstract The incompressible laminar and two-dimensional flow in narrow rectangular channels filled with ladder-type spacers that have the transverse filaments adjacent to a semi-permeable wall, was investigated in order to have insight on the feed flow in a nanofiltration (NF)/reverse osmosis (RO) spiral wound Module. The study was based on numerical simulations and on experiments of flow visualisation with tracer injection and pressure drop measurements. The numerical simulations were performed assuming fully developed laminar flow quasi-periodically repeating in successive inter-filament regions. Ladder-type spacers with inter-filament distances/channel height ratios ( L f ) of 1.9, 3.8 and 5.7 were investigated. The ratio ( P f ) between the transverse filaments height and channel height was investigated between 0.25 and 0.75 in the numerical study and was fixed to 0.5 in the experiments. Flow visualisation with tracer injection and friction factor measurements were made for the water flow in a spacer-filled rectangular channel with 2 mm height, 30 mm wide and 200 mm long, in the range of Reynolds numbers (based on the channel height and on the average inlet velocity) between 50 and 1000. These results show that for increasing inter-filament distances the transition critical Reynolds number decreases from 300 to 150. Below this critical value, the flow is observed to be laminar and two-dimensional. The numerical simulations show that the flow structures are associated to the occurrence of recirculation zones downstream each transverse filament. For low values of the Reynolds number and P f and high values of L f , the recirculation region does not reach the second filament, while for high values of the Reynolds number and P f and low values of L f the recirculation region extends from the first to the second filament. Additionally, for P f =0.75, a secondary recirculation region can be formed inside the main recirculation region. Each of these situations is associated to different patterns of concentration boundary layers growth and subsequently different solute concentration distributions at the membrane surface.

Manish Jain - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of a forward osmosis and a pressure-retarded osmosis spiral wound Module using the Spiegler-Kedem model and experimental validation
    Separation and Purification Technology, 2016
    Co-Authors: Dinesh Attarde, Manish Jain, Sharad Kumar Gupta
    Abstract:

    Abstract A mathematical model is developed for a spiral wound Module for both forward osmosis (FO) and pressure-retarded osmosis (PRO) applications. This model is obtained by combining the membrane transport, external concentration polarization, and internal concentration polarization models with the pressure drop and mass balance equations for both the feed as well as the draw solutions. The Spiegler-Kedem (SK) model is used for describing the local mass transport in the active layer of the membrane. In addition, a new expression is established for determining the internal concentration polarization in the support layer of the membrane. A nonlinear constrained optimization technique is then applied, along with the experimental data for FO and PRO, to predict the unknown parameters of the mathematical model for the spiral wound Module. To ensure the validity of the proposed model and predicted parameters, the model is again used to predict and compare the performance of the Module at a variety of operating conditions. Apart from this, the product recovery and the energy extraction efficiency of the Module at a variety of operating conditions are also analyzed. Lastly, we have tried to answer the question, whether the Solution Diffusion (SD) based model or the SK based model is better for design and analysis, and for obtaining the optimal operating conditions for both FO as well as PRO applications.

  • Influence of hydrocarbon species on the removal of thiophene from FCC gasoline by using a spiral wound pervaporation Module
    Journal of Membrane Science, 2016
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    Pervaporation is an emerging technology in the field of thiophene removal from the Fluid Catalytic Cracker (FCC) gasoline. The performance of pervaporation process for thiophene removal depends on different types of hydrocarbon species present in the FCC gasoline due to their distinctive transport properties in the membrane, as well as due to their distinct physical and thermal properties. In membrane Modules, the presence of different hydrocarbon species may also affect the variations in flow variables such as the temperature and concentrations in the feed and permeate channels. This in turn may further influence the performance of the Module. The present study shows how different hydrocarbon species present in the gasoline influence the performance of a spiral wound Module. First, the experimental data for a number of binary mixtures are obtained for a variety of hydrocarbons and thiophene. This data is then analysed by using a mathematical model for the spiral wound Module. The membrane transport parameters are determined by using a parameter estimation technique. The results indicate that the thiophene (C4H4S) removal from different binary mixtures may be sorted out based on the type of hydrocarbon species present in the binary mixtures as linear alkane>alkene>branched alkane>aromatic compounds. Results for a ternary mixture show that the same mathematical model may also be used for predictions of the Module performance by assuming the ternary mixture to be equivalent to a binary mixture of two species: first is thiophene, and second species is a pseudo-species, having the average physical properties of two other hydrocarbons present in the ternary mixture. The same approach may be extended to a multicomponent feed of a real FCC gasoline, containing a variety of hydrocarbons and sulphur containing compounds. This approach may provide sufficiently accurate predictions with much lesser efforts in comparison to more rigorous, and much more tedious, multicomponent modelling.

  • Osmotically driven membrane processes by using a spiral wound Module - modeling, experimentation and numerical parameter estimation.
    Desalination, 2015
    Co-Authors: Dinesh Attarde, Manish Jain, Kshitij Chaudhary, Sharad Kumar Gupta
    Abstract:

    Abstract Pressure retarded osmosis (PRO) and forward osmosis (FO) are osmotically driven membrane processes and emerging as viable methods for capturing clean energy and producing fresh water from sea water, respectively. The critical problems restricting the application of these processes are the accurate design and analysis of the membrane Module or Module configurations. Hence, a mathematical model is obtained to predict the performance of a spiral wound membrane Module for osmotically driven membrane processes. Transport phenomena through the membrane are described by the previously proposed solution diffusion based model. In the current work, this model is coupled with the differential mass balances on the feed and permeate sides of the Module. In addition, the Darcy's theory is used in the model to incorporate the pressure drop in the channels of Module. The finite difference method is employed to solve coupled algebraic and ordinary differential equations. Here, we also employ a combination of two optimization techniques (Univariate and Fibonacci three point methods) with laboratory scale experimental data points to estimate the unknown parameters of the model. These estimated parameters are then used to predict the performance of FO and PRO at some other operating conditions and validate the mathematical model. Relatively lower maximum power density is observed at a lower draw side hydraulic pressure in the spiral wound Module as compared to power density in a membrane test cell. The experimental results obtained by this Module matched well with the model predictions.

  • Removal of thiophene from n-heptane/thiophene mixtures by spiral wound pervaporation Module: Modelling, validation and influence of operating conditions
    Journal of Membrane Science, 2015
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    In recent years, pervaporation has been investigated rigorously for separation of thiophene and its derivatives from the fluid catalytic cracker (FCC) gasoline. Like other membrane-based processes, the scale up and commercialization of this process require the study of the separation performance at the membrane Module scale. In this study, a suitable mathematical model is obtained to predict the performance of a spiral wound pervaporative Module for the removal of thiophene from n-heptane/thiophene mixtures. The experiments were performed on a Polydimethylsiloxane (PDMS) based spiral wound Module for a variety of operating conditions. The model predictions showed good agreement with the experiment results. Results indicate that the Module performance may be improved with higher permeate pressures and the lower feed temperatures. However, this trend may not be universal and may be altered for some different feed systems or membranes, which shows the necessity to analyse every feed system and membrane material for determining the optimum operating conditions. Simulations also demonstrated that the variations in flow variables along the feed and permeate channels may also have profound effects on the Module performances. Finally, the performance of a pervaporation process was simulated by using a number of spiral wound Modules in series, which demonstrated that the pervaporation might successfully remove thiophene from FCC gasoline up to any desired limit.

Dinesh Attarde - One of the best experts on this subject based on the ideXlab platform.

  • Modeling of a forward osmosis and a pressure-retarded osmosis spiral wound Module using the Spiegler-Kedem model and experimental validation
    Separation and Purification Technology, 2016
    Co-Authors: Dinesh Attarde, Manish Jain, Sharad Kumar Gupta
    Abstract:

    Abstract A mathematical model is developed for a spiral wound Module for both forward osmosis (FO) and pressure-retarded osmosis (PRO) applications. This model is obtained by combining the membrane transport, external concentration polarization, and internal concentration polarization models with the pressure drop and mass balance equations for both the feed as well as the draw solutions. The Spiegler-Kedem (SK) model is used for describing the local mass transport in the active layer of the membrane. In addition, a new expression is established for determining the internal concentration polarization in the support layer of the membrane. A nonlinear constrained optimization technique is then applied, along with the experimental data for FO and PRO, to predict the unknown parameters of the mathematical model for the spiral wound Module. To ensure the validity of the proposed model and predicted parameters, the model is again used to predict and compare the performance of the Module at a variety of operating conditions. Apart from this, the product recovery and the energy extraction efficiency of the Module at a variety of operating conditions are also analyzed. Lastly, we have tried to answer the question, whether the Solution Diffusion (SD) based model or the SK based model is better for design and analysis, and for obtaining the optimal operating conditions for both FO as well as PRO applications.

  • Influence of hydrocarbon species on the removal of thiophene from FCC gasoline by using a spiral wound pervaporation Module
    Journal of Membrane Science, 2016
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    Pervaporation is an emerging technology in the field of thiophene removal from the Fluid Catalytic Cracker (FCC) gasoline. The performance of pervaporation process for thiophene removal depends on different types of hydrocarbon species present in the FCC gasoline due to their distinctive transport properties in the membrane, as well as due to their distinct physical and thermal properties. In membrane Modules, the presence of different hydrocarbon species may also affect the variations in flow variables such as the temperature and concentrations in the feed and permeate channels. This in turn may further influence the performance of the Module. The present study shows how different hydrocarbon species present in the gasoline influence the performance of a spiral wound Module. First, the experimental data for a number of binary mixtures are obtained for a variety of hydrocarbons and thiophene. This data is then analysed by using a mathematical model for the spiral wound Module. The membrane transport parameters are determined by using a parameter estimation technique. The results indicate that the thiophene (C4H4S) removal from different binary mixtures may be sorted out based on the type of hydrocarbon species present in the binary mixtures as linear alkane>alkene>branched alkane>aromatic compounds. Results for a ternary mixture show that the same mathematical model may also be used for predictions of the Module performance by assuming the ternary mixture to be equivalent to a binary mixture of two species: first is thiophene, and second species is a pseudo-species, having the average physical properties of two other hydrocarbons present in the ternary mixture. The same approach may be extended to a multicomponent feed of a real FCC gasoline, containing a variety of hydrocarbons and sulphur containing compounds. This approach may provide sufficiently accurate predictions with much lesser efforts in comparison to more rigorous, and much more tedious, multicomponent modelling.

  • Osmotically driven membrane processes by using a spiral wound Module - modeling, experimentation and numerical parameter estimation.
    Desalination, 2015
    Co-Authors: Dinesh Attarde, Manish Jain, Kshitij Chaudhary, Sharad Kumar Gupta
    Abstract:

    Abstract Pressure retarded osmosis (PRO) and forward osmosis (FO) are osmotically driven membrane processes and emerging as viable methods for capturing clean energy and producing fresh water from sea water, respectively. The critical problems restricting the application of these processes are the accurate design and analysis of the membrane Module or Module configurations. Hence, a mathematical model is obtained to predict the performance of a spiral wound membrane Module for osmotically driven membrane processes. Transport phenomena through the membrane are described by the previously proposed solution diffusion based model. In the current work, this model is coupled with the differential mass balances on the feed and permeate sides of the Module. In addition, the Darcy's theory is used in the model to incorporate the pressure drop in the channels of Module. The finite difference method is employed to solve coupled algebraic and ordinary differential equations. Here, we also employ a combination of two optimization techniques (Univariate and Fibonacci three point methods) with laboratory scale experimental data points to estimate the unknown parameters of the model. These estimated parameters are then used to predict the performance of FO and PRO at some other operating conditions and validate the mathematical model. Relatively lower maximum power density is observed at a lower draw side hydraulic pressure in the spiral wound Module as compared to power density in a membrane test cell. The experimental results obtained by this Module matched well with the model predictions.

  • Removal of thiophene from n-heptane/thiophene mixtures by spiral wound pervaporation Module: Modelling, validation and influence of operating conditions
    Journal of Membrane Science, 2015
    Co-Authors: Manish Jain, Dinesh Attarde, Sharad Kumar Gupta
    Abstract:

    In recent years, pervaporation has been investigated rigorously for separation of thiophene and its derivatives from the fluid catalytic cracker (FCC) gasoline. Like other membrane-based processes, the scale up and commercialization of this process require the study of the separation performance at the membrane Module scale. In this study, a suitable mathematical model is obtained to predict the performance of a spiral wound pervaporative Module for the removal of thiophene from n-heptane/thiophene mixtures. The experiments were performed on a Polydimethylsiloxane (PDMS) based spiral wound Module for a variety of operating conditions. The model predictions showed good agreement with the experiment results. Results indicate that the Module performance may be improved with higher permeate pressures and the lower feed temperatures. However, this trend may not be universal and may be altered for some different feed systems or membranes, which shows the necessity to analyse every feed system and membrane material for determining the optimum operating conditions. Simulations also demonstrated that the variations in flow variables along the feed and permeate channels may also have profound effects on the Module performances. Finally, the performance of a pervaporation process was simulated by using a number of spiral wound Modules in series, which demonstrated that the pervaporation might successfully remove thiophene from FCC gasoline up to any desired limit.