Numerical investigation of electrocoalescence-induced fluid demixing between parallel plates

Year 2024, Volume: 8 Issue: 4, 303 - 318

Aslı Tiktaş

Abstract

The efficient separation of dispersed phase droplets from a continuous phase in multiphase flow systems is essential for industries such as petroleum refining, pharmaceuticals, and food production. Conventional methods, relying on gravitational and buoyancy forces, are often inadequate for small droplets due to their weak influence. Electrocoalescence, utilizing electrical forces to enhance droplet coalescence, has gained attention as a promising alternative. However, most studies have focused on simplified models, limited electrical potentials, or axis-symmetric configurations, overlooking the effects of varying electrical potentials on droplet behavior in complex flows. This study bridges that gap by developing a numerical solver that couples the phase-field method with the Navier-Stokes equations to simulate electrocoalescence of two-dimensional droplets in laminar phase flow between parallel plates. The solver provides detailed insights into multiphase flow dynamics, including contact line behavior and interface tracking under different electrical potentials. The novelty of this work lies in its systematic evaluation of how varying electrical potentials affect droplet deformation, separation time, and interface dynamics, which are often not fully addressed by standard commercial solvers. The findings indicated that increasing electrical potentials from 50 kV to 100 kV leads to droplet deformation, with the droplet deformation index (DDI) increasing from 0.35 to 0.52. Additionally, phase separation time decreases by 20%, from 0.15 seconds to 0.12 seconds, as electrical potential increases. The increasing electrical potentials lead to asymmetric droplet shapes and instability, accelerating separation by disrupting the formation of stable liquid bridges. These findings offer valuable insights into optimizing electrocoalescence processes for industrial applications. In this study, a multi-objective optimization process was conducted using the Non-dominated Sorting Genetic Algorithm II (NSGA-II), with the aim of minimizing droplet deformation and phase separation time. The optimization results revealed that the ideal initial contact angle for minimizing deformation was 123.45°, while the optimal contact angle for minimizing separation time was 145.67°. These results highlight the potential of optimizing system parameters to improve the efficiency and stability of electrocoalescence processes in various industrial applications.The current study provides a deeper understanding of the interaction between electrical forces and multiphase flow dynamics, laying the groundwork for advancements in phase separation technologies across various industries.

Keywords

multiphase flow, electrocoalescence, phase separation, numerical modelling, phase field method

Ethical Statement

The study is complied with research and publication ethics

Supporting Institution

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

References

• Eow, J. S., Ghadiri, M., & Sharif, A. O. (2002). Electrostatic and hydrodynamic separation of aqueous drops in a flowing viscous oil. Chemical Engineering and Processing: Process Intensification, 41(8), 649–657.
• Wu, J., Xu, Y., Dabros, T., & Hamza, H. (2003). Effect of demulsifier properties on destabilization of water-in-oil emulsion. Energy & Fuels, 17(6), 1554–1559.
• Dezhi, S., Chung, J. S., Xiaodong, D., & Ding, Z. (1999). Demulsification of water-in-oil emulsion by wetting coalescence materials in stirred-and packed-columns. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 150(1–3), 69–75.
• Klasson, K. T., Taylor, P. A., Walker, J. F., Jr, Jones, S. A., Cummins, R. L., & Richardson, S. A. (2005). Modification of a centrifugal separator for in-well oil-water separation. Separation Science and Technology, 40(1–3), 453–462.
• Scalarone, D., & Chiantore, O. (2004). Separation techniques for the analysis of artists’ acrylic emulsion paints. Journal of Separation Science, 27(4), 263–274.
• Pouliot, Y., Conway, V., & Leclerc, P. (2014). Separation and concentration technologies in food processing. In Food processing: Principles and applications (pp. 33–60).
• Yesair, D. W., & Coutinho, C. B. (1970). Method for extraction and separation of drugs and metabolites from biological tissue. Biochemical Pharmacology, 19(5), 1569–1578.
• Abeynaike, A., Sederman, A. J., Khan, Y., Johns, M. L., Davidson, J. F., & Mackley, M. R. (2012). The experimental measurement and modelling of sedimentation and creaming for glycerol/biodiesel droplet dispersions. Chemical Engineering Science, 79, 125–137.
• Narváez-Muñoz, C., Hashemi, A. R., Hashemi, M. R., Segura, L. J., & Ryzhakov, P. B. (2024). Computational electrohydrodynamics in microsystems: A review of challenges and applications. Archives of Computational Methods in Engineering.
• Santra, S., Mandal, S., & Chakraborty, S. (2021). Phase-field modeling of multicomponent and multiphase flows in microfluidic systems: A review. International Journal of Numerical Methods for Heat & Fluid Flow, 31(10), 3089–3131.
• Li, J., Zheng, D., & Zhang, W. (2023). Advances of phase-field model in the numerical simulation of multiphase flows: A review. Atmosphere, 14(8), 1311.
• Abbasi, M. S., Song, R., Cho, S., & Lee, J. (2020). Electro-hydrodynamics of emulsion droplets: Physical insights to applications. Micromachines, 11(10), 942.
• Chen, L.-Q., & Zhao, Y. (2022). From classical thermodynamics to phase-field method. Progress in Materials Science, 124, 100868.
• Jain, S. S. (2022). Accurate conservative phase-field method for simulation of two-phase flows. Journal of Computational Physics, 469, 111529.
• Brenner, H. (2013). Interfacial transport processes and rheology. Elsevier.
• Sherwood, J. D. (1988). Breakup of fluid droplets in electric and magnetic fields. Journal of Fluid Mechanics, 188, 133–146.
• Cahn, J. W., & Hilliard, J. E. (1958). Free energy of a nonuniform system. I. Interfacial free energy. Journal of Chemical Physics, 28(2), 258–267.
• Probstein, R. F. (2005). Physicochemical hydrodynamics: An introduction. John Wiley & Sons.
• Krotov, V. V., & Rusanov, A. I. (1999). Physicochemical hydrodynamics of capillary systems. World Scientific.
• Lippmann, G. (1875). Démonstration élémentaire de la formule de Laplace. Journal de Physique Théorique et Appliquée, 4(1), 332–333.
• Dupré, A., & Dupre, P. (1969). Théorie mécanique de la chaleur. Gauthier-Villars.
• Li, X., Bodziony, F., Yin, M., Marschall, H., Berger, R., & Butt, H.-J. (2023). Kinetic drop friction. Nature Communications, 14(1), 4571.
• Butt, H.-J., et al. (2022). Contact angle hysteresis. Current Opinion in Colloid & Interface Science, 59, 101574.
• López-Herrera, J. M., Popinet, S., & Herrada, M. (2011). A charge-conservative approach for simulating electrohydrodynamic two-phase flows using volume-of-fluid. Journal of Computational Physics, 230(5), 1939–1955.
• Yang, Q., Li, B. Q., & Ding, Y. (2013). 3D phase field modeling of electrohydrodynamic multiphase flows. International Journal of Multiphase Flow, 57, 1–9.
• Fernandez, A., Tryggvason, G., Che, J., & Ceccio, S. L. (2005). The effects of electrostatic forces on the distribution of drops in a channel flow: Two-dimensional oblate drops. Physics of Fluids, 17(9).
• Maehlmann, S., & Papageorgiou, D. T. (2009). Numerical study of electric field effects on the deformation of two-dimensional liquid drops in simple shear flow at arbitrary Reynolds number. Journal of Fluid Mechanics, 626, 367–393.
• Lin, Y., Skjetne, P., & Carlson, A. (2012). A phase field model for multiphase electro-hydrodynamic flow. International Journal of Multiphase Flow, 45, 1–11.
• Hadidi, H., Kamali, R., & Manshadi, M. K. D. (2020). Numerical simulation of a novel non-uniform electric field design to enhance the electrocoalescence of droplets. European Journal of Mechanics-B/Fluids, 80, 206–215.
• Utiugov, G., Chirkov, V., & Reznikova, M. (2021). Application of the arbitrary Lagrangian-Eulerian method to simulate electrical coalescence and its experimental verification. International Journal of Plasma Environmental Science & Technology, 15.
• Sun, Z., Li, N., Li, W., Weng, S., Liu, T., & Wang, Z. (2024). Effect of droplet angle on droplet coalescence under high-frequency pulsed electric fields: Experiments and molecular dynamics simulations. Chemical Engineering Science, 295, 120195.
• Zhang, Z., Gao, M., Zhou, W., Wang, D., & Wang, Y. (2023). The numerical simulation of behaviors of oil-water-emulsion flow in pores by using phase field method. Petroleum Science and Technology.
• Alizadeh Majd, S., Moghimi Zand, M., Javidi, R., & Rahimian, M. H. (2023). Numerical investigation of electrohydrodynamic effect for size-tunable droplet formation in a flow-focusing microfluidic device. Soft Materials, 21(2), 174–190.
• Ou, G., Li, J., Jin, Y., & Chen, M. (2023). Droplet coalescence of W/O emulsions under an alternating current electric field. Industrial & Engineering Chemistry Research, 62(17), 6723–6733.
• Comsol. (2023). IEEE Microwave Magazine, 24(2). https://doi.org/10.1109/mmm.2022.3229860
• Kim, J. (2012). Phase-field models for multi-component fluid flows. Communications in Computational Physics, 12(3), 613–661.
• Jacqmin, D. (2000). Contact-line dynamics of a diffuse fluid interface. Journal of Fluid Mechanics, 402, 57–88.
• MathWorks. (2022). MATLAB (R2022a). The MathWorks Inc.
• Danish, M. (2022). Contact angle studies of hydrophobic and hydrophilic surfaces. In Handbook of Magnetic Hybrid Nanoalloys and their Nanocomposites (pp. 1–22). Springer.
• Zhu, Y., et al. (2023). Prediction of contact angle for oriented hydrophobic surface and experimental verification by micro-milling. Coatings, 13(8), 1305.
• Voinov, O. V. (1976). Hydrodynamics of wetting. Fluid Dynamics, 11(5), 714–721.
• Tiktaş, A., Gunerhan, H., & Hepbasli, A. (2023). Exergy and sustainability-based optimisation of flat plate solar collectors by using a novel mathematical model. International Journal of Exergy, 42(2), 192–215.