Simulation of Forward Osmosis Flow in a Two-Dimensional Asymmetric Membrane Channel With Draw Channel Circular Baffle Implementation

2016 ◽  
Author(s):  
James R. L. Koch ◽  
Ramesh K. Agarwal
Keyword(s):  
Osmotic Pressure ◽  
Pressure Loss ◽  
Membrane Filtration ◽  
Concentration Polarization ◽  
Fluid Dynamic ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Cfd Modeling ◽  
Asymmetric Membrane ◽  
Asymmetric Membranes

Forward Osmosis (FO) driven asymmetric membrane filtration is a developing technology which shows promise for seawater desalination and wastewater treatment. Due to the fact that asymmetric membranes are widely used in conjunction with this technology, internal concentration polarization (ICP), a flow-entrainment effect occurring within such membranes, is a significant if not dominant source of overall osmotic pressure loss across the membrane. Accurate modeling of ICP effects is therefore very critical for accurate Computational Fluid Dynamic (CFD) modeling of asymmetric membranes. A related, dilutive effect known as external concentration polarization (ECP) also develops on both the rejection and draw sides of the membrane, further contributing to osmotic pressure loss. In order to increase the overall water flux, circular spacers can be implemented within the draw channel of FO cross-flow membrane exchange units to decrease the effects of ICP and draw ECP. The drawback of spacer inclusions is an increased pressure loss across the length of the feed channel. The system efficiency gained by the decrease in ECP must therefore be weighed against the energy cost of hydraulically making up lost channel pressure. To model the geometry of a FO cross-flow channel, the open source CFD package OpenFOAM is used. A compressible flow model with explicit boundary conditions is developed to simulate the flux transfer and ICP effects present within an asymmetric membrane when exposed to a NaCl solution. Results are validated by comparison with the numerical data generated by earlier models of asymmetric membranes implemented by other investigators using similar simulation conditions.

Simulation of Forward Osmosis Flow in a Two-Dimensional Asymmetric Membrane Channel With Draw Channel Circular Baffle Implementation

2015 ◽  
Author(s):  
James R. L. Koch ◽  
Ramesh K. Agarwal
Keyword(s):  
Osmotic Pressure ◽  
Pressure Loss ◽  
Membrane Filtration ◽  
Concentration Polarization ◽  
Fluid Dynamic ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Cfd Modeling ◽  
Asymmetric Membrane ◽  
Asymmetric Membranes

Forward Osmosis (FO) driven asymmetric membrane filtration is a developing technology which shows promise for seawater desalination and wastewater treatment. Due to the fact that asymmetric membranes are widely used in conjunction with this technology, internal concentration polarization (ICP), a flow-entrainment effect occurring within such membranes, is a significant if not dominant source of overall osmotic pressure loss across the membrane. Accurate modeling of ICP effects is therefore very critical for accurate Computational Fluid Dynamic (CFD) modeling of asymmetric membranes. A related, dilutive effect known as external concentration polarization (ECP) also develops on both the rejection and draw sides of the membrane, further contributing to osmotic pressure loss. In order to increase the overall water flux, circular spacers can be implemented within the draw channel of FO cross-flow membrane exchange units to decrease the effects of ICP and draw ECP. The drawback of spacer inclusions is an increased pressure loss across the length of the feed channel. The system efficiency gained by the decrease in ECP must therefore be weighed against the energy cost of hydraulically making up lost channel pressure. To model the geometry of a FO cross-flow channel, the open source CFD package OpenFOAM is used. A compressible flow model with explicit boundary conditions is developed to simulate the flux transfer and ICP effects present within an asymmetric membrane when exposed to a NaCl solution. Results are validated by comparison with the numerical data generated by earlier models of asymmetric membranes implemented by other investigators using similar simulation conditions.

scholarly journals Superparamagnetic Fe3O4@CA Nanoparticles and Their Potential as Draw Solution Agents in Forward Osmosis

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2965
Author(s):  
Irena Petrinic ◽  
Janja Stergar ◽  
Hermina Bukšek ◽  
Miha Drofenik ◽  
Sašo Gyergyek ◽  
...  
Keyword(s):  
Osmotic Pressure ◽  
Magnetic Measurements ◽  
Water Flux ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Solute Flux ◽  
Colloidal Solutions ◽  
Initial Water ◽  
Cross Flow Filtration ◽  
Draw Solution

In this study, citric acid (CA)-coated magnetite Fe3O4 magnetic nanoparticles (Fe3O4@CA MNPs) for use as draw solution (DS) agents in forward osmosis (FO) were synthesized by co-precipitation and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), transmission electron microscopy (TEM) and magnetic measurements. Prepared 3.7% w/w colloidal solutions of Fe3O4@CA MNPs exhibited an osmotic pressure of 18.7 bar after purification without aggregation and a sufficient magnetization of 44 emu/g to allow DS regeneration by an external magnetic field. Fe3O4@CA suspensions were used as DS in FO cross-flow filtration with deionized (DI) water as FS and with the active layer of the FO membrane facing the FS and NaCl as a reference DS. The same transmembrane bulk osmotic pressure resulted in different water fluxes for NaCl and MNPs, respectively. Thus the initial water flux with Fe3O4@CA was 9.2 LMH whereas for 0.45 M NaCl as DS it was 14.1 LMH. The reverse solute flux was 0.08 GMH for Fe3O4@CA and 2.5 GMH for NaCl. These differences are ascribed to a more pronounced internal dilutive concentration polarization with Fe3O4@CA as DS compared to NaCl as DS. This research demonstrated that the proposed Fe3O4@CA can be used as a potential low reverse solute flux DS for FO processes.

Measurement of Combustion Air to a Typical Cyclone Burner With a Common Wind Box and Pressure Loss Effects on the Cyclone Due to Inlet Configuration

2009 ◽  
Author(s):  
Robert O. Brandt
Keyword(s):  
Pressure Loss ◽  
Cross Flow ◽  
Flow Distribution ◽  
Cfd Modeling ◽  
Width Ratio ◽  
Worst Case ◽  
Air Inlet ◽  
Large Length ◽  
Coal Flow ◽  
Case Condition

To maintain proper fuel air ratio and minimize NOx during combustion, air and coal flow into a cyclone burner must be measured. Due to the large length to width ratio of the air inlet to some burners, often greater than 7, accurate measurement has proven to be difficult; in fact, measurement with a ratio greater than 2 to 1 has proven to be difficult. A typical cyclone burner system was analyzed with a premium CFD modeling package, with particular attention being given to the location which would be considered “worst case”. If this location can be measured accurately, then we can assume that the less stringent locations will also be measured accurately. Additionally, a “best case” was also analyzed to compare pressure loss due to the measurement. The worst case location was chosen based on a cross flow condition of the air just going around the corner at the entrance, where the flow velocity is the highest. See Figure A. The “best case” condition was chosen as the air flow entering the inlet normal to the plane of the inlet, although this condition may not actually exist in the example wind box chosen. Three inlet configurations were analyzed, (1) three optimally designed Oval High Betas across the inlet, (2) two optimally designed Oval High Betas across the inlet and (3) the flow distribution across the inlet as is, with no method to break up the large length to width ratio. Of particular interest, once the analysis for both the “worst case” and “best case” were done for the three inlet configurations, one configuration, proved best for both measurement and pressure loss—condition (1), the three optimally designed Oval High Betas.

scholarly journals Effect of Osmotic Pressure on Whey Protein Concentration in Forward Osmosis

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 573
Author(s):  
Pelin Oymaci ◽  
Pauline E. Offeringa ◽  
Zandrie Borneman ◽  
Kitty Nijmeijer
Keyword(s):  
Osmotic Pressure ◽  
Driving Force ◽  
Protein Concentration ◽  
Concentration Polarization ◽  
Forward Osmosis ◽  
Protein Fouling ◽  
Flux Decline ◽  
Concentration Factors ◽  
Absolute Concentrations ◽  
Flux Increase

Forward osmosis (FO) is an emerging process to dewater whey streams energy efficiently. The driving force for the process is the concentration gradient between the feed (FS) and the concentrated draw (DS) solution. Here we investigate not only the effect of the DS concentration on the performance, but also that of the FS is varied to maintain equal driving force at different absolute concentrations. Experiments with clean water as feed reveal a flux increase at higher osmotic pressure. When high product purities and thus low reverse salt fluxes are required, operation at lower DS concentrations is preferred. Whey as FS induces severe initial flux decline due to instantaneous protein fouling of the membrane. This is mostly due to reversible fouling, and to a smaller extent to irreversible fouling. Concentration factors in the range of 1.2–1.3 are obtained. When 0.5 M NaCl is added to whey as FS, clearly lower fluxes are obtained due to more severe concentration polarization. Multiple runs over longer times show though that irreversible fouling is fully suppressed due to salting in/out effects and flux decline is the result of reversible fouling only.

scholarly journals Dynamical Modeling of Water Flux in Forward Osmosis with Multistage Operation and Sensitivity Analysis of Model Parameters

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 31
Author(s):  
Hoyoung Ryu ◽  
Azeem Mushtaq ◽  
Eunhye Park ◽  
Kyochan Kim ◽  
Yong Keun Chang ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Concentration Polarization ◽  
Water Flux ◽  
Forward Osmosis ◽  
Solute Diffusion ◽  
Model Parameters ◽  
Sensitivity Index ◽  
Water Recovery ◽  
Asymmetric Membrane ◽  
Simulation Results

To mathematically predict the behavior of a forward osmosis (FO) process for water recovery, a model was constructed using an asymmetric membrane and glucose as a draw solution, allowing an examination of both phenomenological and process aspects. It was found that the proposed model adequately described the significant physicochemical phenomena that occur in the FO system, including forward water flux, internal concentration polarization (ICP), external concentration polarization (ECP), and reverse solute diffusion (RSD). Model parameters, namely the physiochemical properties of the FO membrane and glucose solutions, were estimated on the basis of experimental and existing data. Through batch FO operations with the estimated parameters, the model was verified. In addition, the influences of ECP and ICP on the water flux of the FO system were investigated at different solute concentrations. Water flux simulation results, which exhibited good agreement with the experimental data, confirmed that ICP, ECP, and RSD had a real impact on water flux and thus must be taken into account in the FO process. With the Latin-hypercube—one-factor-at-a-time (LH–OAT) method, the sensitivity index of diffusivity was at its highest, with a value of more than 40%, which means that diffusivity is the most influential parameter for water flux of the FO system, in particular when dealing with a high-salinity solution. Based on the developed model and sensitivity analysis, the simulation results provide insight into how mass transport affects the performance of an FO system.

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