Simulation of turbulent electrocoalescence

This work applied three-dimensional and volume of fluid (VOF) model of computational fluid dynamic (CFD) simulation to demonstrate the movement of liquid-liquid interface in a primary oil-water separator. Basic sediment and water as well as salt removal had been used as criteria for the separator efficiency, experimentally. Water removal from organic phase was considered as the efficiency using CFD. Simulation was performed for different water levels and the way this parameter can influence the efficiency was studied. Experimental and CFD simulation results were in relative agreement and showed that the optimum water level is 58 and 50 % of separator's diameter, respectively.

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“…The only way to speed up the sedimentation process is to make small water droplets coalesce into larger ones [34]. analysis [28,[35][36][37][38].…”

Section: Resultsmentioning

confidence: 99%

Experimental and Computational Analysis on Influence of Water Level on Oil-Water Separator Efficiency

Behin

Azimi

2015

Separation Science and Technology

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“…However, their model was dependent on tuning parameter of slip length and some closure sub-models to consider the fluid state of drop. Later, Melheim and Chiesa [25] have modified a new model, the cluster integration method, whose validity is more doubtful. Bresciani et al [26] have studied droplet-droplet coalescence under the influence of an electric field through analytical solution.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Collision and Coalescence of Water Droplets in an Electric Field

Mohammadi

Shahhosseini

Bayat³

2013

Chem Eng & Technol

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The coalescence of binary water droplets in oil exposed to an external electric field is simulated using a model including both electrostatic and hydrodynamic sections. Available mathematical models for electric dipole-dipole force are presented in the first part of the model. Volume of Fluid approach is applied in the second part of the model. The simulation results were in good agreement with the published experimental observations. The results indicated that an improvement in electrocoalescence speed could be achieved. It was also revealed that the skew angle of the electric field, the oil viscosity, and the initial drops distance influence the electrocoalescence. Moreover, a correlation was developed to predict electrocoalescence kinetic as a function of the participant parameters.

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“…Only averaged quantities are obtained, and models for the drag, mass‐transfer coefficients, and turbulence closures need to be provided. To model the turbulence, most simulations of the continuous phases have been based on Reynolds‐averaged Navier Stokes (RANS) equations34–36 and large eddy simulations (LES) 37–42. The literature concerning such macroscale approaches is extensive37, 43 and includes either Euler‐Euler or Euler‐Lagrangian methods.…”

Section: Introductionmentioning

confidence: 99%

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

2007

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In this work, high-resolution 2-D numerical simulations were performed on the motion of deformable bubbles in non-Newtonian fluids and the associated mass transfer. For that purpose, we have implemented a semi-Lagrangian advection scheme and improved the fluid dynamic calculation by the usage of implicit algorithms. Non-Newtonian fluids are described by generalized Newtonian as well as viscoelastic model fluids. As shear-thinning model we use a Power-Law and a Carreau-Yasuda model, the viscoelastic fluid simulations are based on an Upper-Convected Maxwell model combined with a recently introduced model for the evolution of the effective shear rate. The mathematical challenges arising from the hyperbolic nature of the resulting set of equations are addressed by inclusion of artificial diffusion in the stress equation. In our work, it was found that shear thinning effects have impact on collision rates, and therefore, may influence coalescence of bubbles in non-Newtonian liquids. Furthermore, for the first time, concentration fields of dissolved gas in viscoelastic fluids are presented. The study shows that the fluid elasticity plays a major role for bubble rise velocity, and therefore, mass transfer. As the wake dynamics differ significantly from that in Newtonian liquids, abnormal mixing characteristics can be expected in the bubbly flow of viscoelastic fluids. 2007 American Institute of Chemical Engineers AIChE J, 53: [1861][1862][1863][1864][1865][1866][1867][1868][1869][1870][1871][1872][1873][1874][1875][1876][1877][1878] 2007 Keywords: numerical simulation, bubbles, non-Newtonian liquids, mass transfer IntroductionBecause of persistent uncertainties in the underlying models and system properties, the scale-up of bioreactors remains a challenging problem. For example, the rheology of media in bioreactors is non-Newtonian in most cases. [1][2][3][4][5][6][7][8] However, details of the non-Newtonian fluid characteristics, such as viscoelasticity or the tendency for shear thinning, are frequently unknown or neglected. Furthermore, in contrast to Newtonian media, there is a lack of general correlations for mass and heat transfer rates, which are needed for the prediction of oxygen supply and heat removal. Similar observations can be made for the properties needed to precisely predict transport of metabolites, nutrients, or CO 2 . So far, most studies are based on experimental investigations, which are usually interpreted with simple theoretical models. 3,4,[8][9][10][11] principles methods to predict mass-transfer coefficients, transport rates, and other parameters in non-Newtonian fluids have not been reported so far. Local mass transfer is not the only micro-effect of central importance in the design of bioreactors. Knowledge of the localized forces, such as shear and normal stresses in the cell's microenvironment, is also a key for determining whether a bioreactor is suitable to handle sensitive biosystems.12 Subcritical shear stresses found in the hydrodynamic environment of large-scale reactors may redu...

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Simulation of turbulent electrocoalescence

Cited by 26 publications

References 30 publications

Experimental and Computational Analysis on Influence of Water Level on Oil-Water Separator Efficiency

Experimental and Computational Analysis on Influence of Water Level on Oil-Water Separator Efficiency

Numerical Study of the Collision and Coalescence of Water Droplets in an Electric Field

Flow and mass transfer of fully resolved bubbles in non‐Newtonian fluids

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