1
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Sun L, Wang J, Chen Y. Coalescence of multiple droplets induced by a constant DC electric field. PLoS One 2024; 19:e0300925. [PMID: 38593131 PMCID: PMC11003697 DOI: 10.1371/journal.pone.0300925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/06/2024] [Indexed: 04/11/2024] Open
Abstract
In this work, the electro-coalescence process of three nanodroplets under a constant DC electric field is investigated via molecular dynamics simulations (MD), aiming to explore the electric manipulation of multiple droplets coalescence on the molecular level. The symmetrical and asymmetrical dynamic evolutions of electrocoalescence process can be observed. Our MD simulations show that there are two types of critical electric fields to induce the special dynamics. The chain configuration can be formed, when one of the critical electric field is exceeded, referred to as Ecc. On the other hand, there is another critical electric field to change the coalescence pattern from complete coalescence to partial coalescence, the so-called Ecn. Finally, we find that the use of the pulsed DC electric field can overcome the drawbacks of the constant DC electric field in the crude oil industry, and the mechanisms behind the suppressed effect of the water chain or non-coalescence are further revealed.
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Affiliation(s)
- Liwei Sun
- School of Mechanical Engineering, Changchun Automobile Industry Institute, Changchun, China
| | - Jian Wang
- College of Computer Science and Technology, Jilin University, Changchun, China
| | - Yanhui Chen
- School of Mechanical Engineering, Changchun Automobile Industry Institute, Changchun, China
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2
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Yuan S, Yang X, Zhang N, Zhang J, Yuan S, Wang Z. Molecular insights into the adsorption and penetration of oil droplets on hydrophobic membrane in membrane distillation. WATER RESEARCH 2024; 253:121329. [PMID: 38387269 DOI: 10.1016/j.watres.2024.121329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 01/19/2024] [Accepted: 02/16/2024] [Indexed: 02/24/2024]
Abstract
Membrane fouling induced by oily substances significantly constrains membrane distillation performance in treating hypersaline oily wastewater. Overcoming this challenge necessitates a heightened fundamental understanding of the oil fouling phenomenon. Herein, the adsorption and penetration mechanism of oil droplets on hydrophobic membranes in membrane distillation process was investigated at the molecular level. Our results demonstrated that the adsorption and penetration of oil droplets were divided into four stages, including the free stage, contact stage, spreading stage, and equilibrium stage. Due to the extensive non-polar surface distribution of the polytetrafluoroethylene (PTFE) membrane (comprising 95.41 %), the interaction between oil molecules and PTFE was primarily governed by van der Waals interaction. Continuous oil droplet membrane fouling model revealed that the new oil droplet molecules preferred to penetrate into membrane pores where oil droplets already existed. The penetration of resin (a component of medium-quality oil droplets) onto PTFE membrane pores required the "pre-paving" of light crude oil. Finally, the ΔE quantitative structure-activity relationships (QSAR) models were developed to evaluate the penetration mechanism of pollutant molecules on the PTFE membrane. This research provides new insights for improving sustainable membrane distillation technologies in treating saline oily wastewater.
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Affiliation(s)
- Shideng Yuan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Xin Yang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Na Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Jiaojiao Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China
| | - Shiling Yuan
- Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan 250100, PR China
| | - Zhining Wang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, PR China.
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3
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Feng H, Shen S, Jin M, Zhang Q, Liu M, Wu Z, Chen J, Yi Z, Zhou G, Shui L. Microwell Confined Electro-Coalescence for Rapid Formation of High-Throughput Droplet Array. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302998. [PMID: 37449335 DOI: 10.1002/smll.202302998] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/14/2023] [Indexed: 07/18/2023]
Abstract
Droplet array is widely applied in single cell analysis, drug screening, protein crystallization, etc. This work proposes and validates a method for rapid formation of uniform droplet array based on microwell confined droplets electro-coalescence of screen-printed emulsion droplets, namely electro-coalescence droplet array (ECDA). The electro-coalescence of droplets is according to the polarization induced electrostatic and dielectrophoretic forces, and the dielectrowetting effect. The photolithographically fabricated microwells are highly regular and reproducible, ensuring identical volume and physical confinement to achieve uniform droplet array, and meanwhile the microwell isolation protects the paired water droplets from further fusion and broadens its feasibility to different fluidic systems. Under optimized conditions, a droplet array with an average diameter of 85 µm and a throughput of 106 in a 10 cm × 10 cm chip can be achieved within 5 s at 120 Vpp and 50 kHz. This ECDA chip is validated for various microwell geometries and functional materials. The optimized ECDA are successfully applied for digital viable bacteria counting, showing comparable results to the plate culture counting. Such an ECDA chip, as a digitizable and high-throughput platform, presents excellent potential for high-throughput screening, analysis, absolute quantification, etc.
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Affiliation(s)
- Haoqiang Feng
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Shitao Shen
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Mingliang Jin
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Qilin Zhang
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Mengjun Liu
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Zihao Wu
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Jiamei Chen
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
- Shenzhen Bao'an District Traditional Chinese Medicine Hospital, Shenzhen, 518133, P. R. China
| | - Zichuan Yi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan, 528402, P. R. China
| | - Guofu Zhou
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Lingling Shui
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
- Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006, P. R. China
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4
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Guo K, Liu X, Du L, Lü Y, Luo X, Ling X. Electrocoalescence Behavior of Droplets Dispersed with Na 2CO 3 in Oil under the Electromagnetic Synergy Field. J Phys Chem B 2023. [PMID: 37311091 DOI: 10.1021/acs.jpcb.3c01217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electromagnetic synergy is a more effective physical method than a single AC electric field (ACEF) to enhance oil-water separation. However, the electrocoalescence behavior of droplets dispersed with salt ions in oil under the synergistic electromagnetic field (EMSF) still lacks research. Herein, the evolution coefficient of liquid bridge diameter (C1) characterizes the growth rate of the liquid bridge diameter, a series of Na2CO3-dispersed droplets with different ionic strengths were prepared, and C1 values of droplets under ACEF and EMSF were compared. Micro high-speed experiments revealed that C1 under ACEF is larger than C1 under EMSF. In particular, when σ = 100 μS·cm-1and E = 629.73 kV·m-1, C1 under the ACEF is 15% larger than C1 under EMSF. Additionally, the theory of ion enrichment is put forward, which explains the influence of salt ions on ζ potential and total surface potential in EMSF. This study provides guidance for designing high-performance devices by introducing electromagnetic synergy in water-in-oil emulsion treatment.
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Affiliation(s)
- Kai Guo
- College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China
| | - Xiaoya Liu
- College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China
| | - Ling Du
- College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China
| | - Yuling Lü
- College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, PR China
| | - Xiaoming Luo
- College of Pipeline and Civil Engineering, China University of Petroleum, Qingdao 266580, PR China
| | - Xiao Ling
- College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China
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Wang SY, Wang ZJ, Wang DQ, Yang YR, Wang XD, Lee DJ. Electrically Manipulated Vapor Condensation on the Dimpled Surface: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:829-840. [PMID: 36594668 DOI: 10.1021/acs.langmuir.2c02897] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Random vapor nucleation leads to flooding condensation with degraded heat-transfer efficiency. Since an external electric field has a significant effect on manipulating droplets' motion, it is possible to be one of the effective methods to hinder flooding phenomena and improve the heat-transfer rate by applying the external electric field during condensation. However, the motion of nanodroplets is more sensitive to the electric field owing to the scale effect on the nanoscale. The effect of the electric field on growth has not explicitly been comprehended. This work studied the condensation processes on a nanodimpled surface under an electric field with various strengths and directions. The results showed that condensed droplets' growth under the electric field depends on the competition between the electric field force and solid-liquid interactions. Increased vertical electric field strength, the higher torsion by the electric field hindered the motion of vapor, decreased the collision frequency for water molecules with the cooled surface, and elongated the cluster when the electric field force dominates, thus deteriorating the condensation performance. While applying the horizontal electric field, the greater electric field strength leads to better condensation performance by the larger contacting area for heat exchange. A wetting transition induced by the electric field was observed when the electric field strength increased to a certain extent (E > 5.2 × 108 V/m in this study). When the V-shaped surface replaced the dimpled surface as the condensed substrate, the same wetting transition phenomena occurred under a more significant horizontal electric field strength, showing that this method is universal. Besides, different electric field frequencies influenced both the growth and the nucleation, thus exhibiting various condensation performances.
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Affiliation(s)
| | | | | | | | | | - Duu-Jong Lee
- Department of Mechanical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon999077, Hong Kong
- Department of Chemical Engineering & Materials Science, Yuan-Ze University, Chungli320, Taiwan
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6
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Liu D, Cao Q, Piao Z, Li L. Confinement Dynamics of Nanodroplets between Two Surfaces: Effects of Wettability and Electric Field. Chemphyschem 2022; 23:e202200184. [PMID: 35986551 DOI: 10.1002/cphc.202200184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 08/15/2022] [Indexed: 01/04/2023]
Abstract
The electrowetting effect and related applications of tiny droplets have aroused widespread research interest. In this work, we report molecular dynamics simulations of confinement dynamics of nanodroplets under different droplet-surface interactions and surface distances under an external electric field. So far, the effect of the surface-droplet interactions on electric field-induced dynamics behaviors of droplets in confined spaces has not been extensively studied. Our results show that in the absence of electric field there is a critical value of surface wettability for the shape transition of droplets. Above this value, the droplet is divided into small droplets adhered on the bottom and top surfaces; below this value, the droplets are detached from the surfaces. When an external electric field is applied parallel to the surfaces, the droplet spreads on the surface along the direction of the electric field. It was found that the surface separation significantly influences the transition of the droplet shape. The steady morphology of the droplets under the electric field depends on the surface-droplet interaction and surface separation. We explore the underlying mechanism causing the morphological transition through analyzing the molecular interactions, the number of interracial molecules and the interaction force between the droplets and surfaces. These results provide basic insights into the molecular interactions of nanodroplets under different confined environments, and clues for applications of confined nanodroplets under the control of electric field.
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Affiliation(s)
- Dandan Liu
- College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P.R. China.,College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
| | - Qianqian Cao
- College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
| | - Zhongyu Piao
- College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P.R. China
| | - Lujuan Li
- College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
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7
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Li B, Ju M, Dou X, Li N, Zhang W, Sun Z, Yu K, Wang J, Wang Z. Assessing nanoparticle-surfactant-salt synergistic effects on droplet–droplet electrocoalescence by molecular dynamics simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Wang Y, Li S, Zhang Y, Zhang Z, Yuan S, Wang D. Effect of electric field on coalescence of an oil-in-water emulsion stabilized by surfactant: a molecular dynamics study. RSC Adv 2022; 12:30658-30669. [PMID: 36337949 PMCID: PMC9597590 DOI: 10.1039/d2ra04731d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/18/2022] [Indexed: 11/07/2022] Open
Abstract
The microscopic understanding of electrocoalescence of oil-in-water (O/W) emulsions stabilized by surfactant is very important to improve the efficiency of electrical demulsification. The behaviors of the coalescence of O/W emulsion stabilized by surfactant in the presence of a direct electric field and a pulsed electric field were explored by nonequilibrium molecular dynamics simulations. According to the simulated results, an electrical method is feasible to demulsify an O/W emulsion stabilized by a surfactant. The configuration and movement of the sodium dodecyl sulfate (SDS) were determined by interactions between SDS molecules themselves and between SDS and oil/water molecules along with the force exerted by the applied electrical field. Two droplets will coalesce into one when the strength of the electric field exceeds 0.4 V nm-1. The SDS group can be broken up by an electric field larger than 0.6 V nm-1. The point when interaction energy between the hexadecane molecules of the two droplets begins to decrease from zero is consistent with the time when the two oil droplets came in contact. The coalescence process can be completed if the two droplets have begun to coalesce, even after the electric field was removed. Otherwise, the coalescence process cannot be completed. To enhance the efficiency of the electrocoalescence of O/W emulsions, strength, frequency and duty ratio of the electric field have to be optimized according to the properties of the emulsion. This research will help us to figure out how electric fields promote the efficiency of electrocoalescence of O/W emulsions with surfactant.
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Affiliation(s)
- Yudou Wang
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
| | - Shiyan Li
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
| | - Yuanwu Zhang
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
| | - Zhenlei Zhang
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
| | - Shundong Yuan
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
| | - Diansheng Wang
- College of Science, China University of Petroleum (East China) Qingdao 266580 China
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9
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Li S, Yuan S, Zhang Y, Guo H, Liu S, Wang D, Wang Y. Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12717-12730. [PMID: 36197725 DOI: 10.1021/acs.langmuir.2c02364] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Application of an electric field is an effective demulsification method for water-in-oil (W/O) emulsions. For the W/O emulsions stabilized by anionic surfactants, the microscopic demulsification mechanism is still not very clear. In this work, the coalescence behavior of two droplets stabilized by the anionic surfactant sodium dodecyl sulfate (SDS) in the oil phase under a DC electric field is investigated by molecular dynamics simulation. The effects of electric field strength and oil type on the electrocoalescence of two water droplets are mainly considered. The trajectory snapshots and center of mass of the two water droplets suggest that there is almost no migratory coalescence. The movement of sodium ions and SDS, which is a combined effect of the electric field force and the resistance from the oil phase, is crucial for the deformation and connection of two water droplets. The results of mean square displacement, radial distribution function, hydration number, and interaction energies of Na+-H2O and SDS-H2O indicate that the sodium ion has a stronger ability to carry water molecules for movement than SDS. The stronger electric field strength will result in more severe deformation and shorter coalescence time. Under the higher electric field strength, the two droplets will be elongated into a slender water ribbon. By applying a pulsed DC electric field with suitable amplitude, frequency, and duty ratio, it is possible to achieve full coalescence for the ionic surfactant-stabilized W/O emulsions. The oil phase also plays an important role for the deformation of droplets and the migration of emulsion components. For the different oil phases, a longer time or stronger electric field strength would be needed for the electrocoalescence of droplets in the oil phase with higher density and viscosity. Our results are expected to be helpful for practical application in the petroleum industry and chemical engineering.
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Affiliation(s)
- Shiyan Li
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Shundong Yuan
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yuanwu Zhang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Huiying Guo
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Sai Liu
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Diansheng Wang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yudou Wang
- College of Science, China University of Petroleum, Qingdao266580, China
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Li B, Ju M, Dou X, Li N, Zhang W, Xu H, Sun Z, Yu K, Wang J, Wang Z. Microscopic mechanism for nanoparticle-laden droplet–droplet electrocoalescence: A molecular dynamics study. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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11
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Liquefaction of water on the hydrophobic surface of black phosphorene: A reactive molecular dynamics simulation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Zhang H, Zhou B, Zhou X, Yang S, Liu S, Wang X, Yuan S, Yuan S. Molecular dynamics simulation of demulsification of O/W emulsion containing soil in direct current electric field. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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13
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Li W, Zeng H, Tang T. Molecular dynamics simulation on water/oil interface with model asphaltene subjected to electric field. J Colloid Interface Sci 2022; 628:924-934. [PMID: 35963177 DOI: 10.1016/j.jcis.2022.08.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 07/24/2022] [Accepted: 08/04/2022] [Indexed: 11/15/2022]
Abstract
HYPOTHESIS The droplet-medium interfaces of petroleum emulsions are often stabilized by the indigenous surface-active compounds (e.g., asphaltenes), causing undesired issues. While demulsification by electric field is a promising technique, fundamental study on the droplet-medium interface influenced by electric field is limited. Molecular dynamics (MD) simulations are expected to provide microscopic insights into the nano-scaled water/oil interface. METHODS MD simulations are conducted to study the adsorption of model asphaltene molecules (represented by N-(1-hexylheptyl)-N'-(5-carboxylicpentyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe)) on a water-toluene interface under various strengths of electric field. The adsorption amount and structural feature of C5Pe molecules at water-toluene interface are investigated, and the effects of electric field and salt are discussed. FINDINGS C5Pe molecules tend to adsorb on the water-oil interface. As the electric field strength increases, the adsorption amount first slightly increases (or remains constant) and then decreases. The electric field disrupts the compact π-π stacking between C5Pe molecules and increases their mobility, causing a dispersed distribution of the molecules with a wide range of orientations relative to the interface. Within the studied range, the addition of salt ions appears to stabilize the interface at high electric field. These results provide useful insights into the mechanism and feasibility of demulsification under electric field.
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Affiliation(s)
- Wenhui Li
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
| | - Tian Tang
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
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14
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Qi Z, Sun Z, Li N, Li W, Sun M, Liu Y, Wang Z. Effect of electric field intensity on electrophoretic migration and deformation of oil droplets in O/W emulsion under DC electric field: A molecular dynamics study. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.118034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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He X, Zhang BX, Wang YF, Zhang YY, Yang YR, Wang XD, Lee DJ. Dynamic coalescence of two charged droplets with deflected angles in the presence of electric fields. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Li N, Sun Z, Pang Y, Qi Z, Liu W, Li W, Sun M, Li B, Wang Z. Microscopic mechanism for electrocoalescence of water droplets in water-in-oil emulsions containing surfactant: A molecular dynamics study. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120756] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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17
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Ou G, Li J, Jin Y, Chen M, Ma Y, Gao K. Behavior Evolution of Droplets Suspended in Castor Oil under Alternating Current Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2084-2093. [PMID: 35119874 DOI: 10.1021/acs.langmuir.1c03182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electric fields, which can promote the approach of droplets and break the liquid film, are extensively used in the separation of the water phase in water-in-oil emulsions. However, there is an evolution of droplet behavior under an electric field. After the two droplets meet with each other, the electric force becomes undesirable, which would even cause breakup of the merged droplet. When the electric field strength E reaches a particular value, the final behavior of droplets is made, which goes against coalescence, and there are lots of behavior evolution types. Several research studies have studied on whether droplets coalesce and the critical condition, but few works have focused on the classification and mechanism of non-coalescence behaviors. In this paper, the behavior evolution of two single droplets suspended in castor oil under an alternating current electric field is studied by a high-speed camera. Six distinct behavior evolution modes are observed and summarized: coalescence, bounce, partial coalescence, partial rupture, coalescence-rupture, and rupture. The behavior evolution mode is influenced by the initial separation distance s0 between droplets and the electric field strength. Moreover, there exist critical electric field strengths among different behavior evolution modes. As E gradually increases, two water droplets go through coalescence, partial coalescence, and coalescence-rupture in sequence when s0 is small and coalescence, bounce, partial rupture, and rupture when s0 is large. The mechanisms of behavior evolution are revealed by investigating the confrontation between electric force and capillary force in the condition with liquid bridge or pressure difference from the surrounding fluid and electric force in the condition without a liquid bridge. In addition, a cone-dimple mode of water droplets in castor oil is found, demonstrating the rationality of electric force theory.
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Affiliation(s)
- Guangyu Ou
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Jun Li
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Yang Jin
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Ming Chen
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Yujing Ma
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
| | - Kaige Gao
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China
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18
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Li N, Sun Z, Sun J, Liu W, Wei L, Li T, Li B, Wang Z. Deformation and breakup mechanism of water droplet in acidic crude oil emulsion under uniform electric field: A molecular dynamics study. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.127746] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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Molecular dynamics simulations of nanoparticle-laden drop–interface electrocoalescence behaviors under direct and alternating current electric fields. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117875] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Wang Z, Li N, Sun Z, Wang X, Chen Q, Liu W, Qi Z, Wei L, Li B. Molecular dynamics study of droplet electrocoalescence in the oil phase and the gas phase. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2021.119622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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He X, Zhang BX, Wang SL, Wang YF, Yang YR, Wang XD, Lee DJ. Electrocoalescence of two charged nanodroplets under different types of external electric fields. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117417] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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22
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Sjöblom J, Mhatre S, Simon S, Skartlien R, Sørland G. Emulsions in external electric fields. Adv Colloid Interface Sci 2021; 294:102455. [PMID: 34102389 DOI: 10.1016/j.cis.2021.102455] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/28/2022]
Abstract
Water is co-produced with crude oils, generally in the form of water-in-crude oil emulsions. The oil and water phases need to be separated before export. Separation is performed in gravity separators with the addition of chemical demulsifiers and, sometimes, with the application of an electric field by using an electrocoalescer. The present article reviews several aspects of electrocoalescence by considering the effect of the electric field from the molecular to a macroscopic scale: the oil-water interface, single drop effects, two drop interactions, and finally emulsions at laboratory scales. Experimental results together with Dissipative Particle Dynamics (DPD) simulation results are presented. The review begins with water-oil interface under an electric field and followed by single drop electrohydrodynamics. The electric field is shown to influence the adsorption of crude oil indigenous surface-active components (asphaltenes) due to the electrohydrodynamic (EHD) flows. The interactions between two droplets in the presence of electric field and the factors governing the drop-drop coalescence are discussed in detail. DPD simulations help to elucidate thin film breakup during (electro)-coalescence of two water droplets, where the oil film has drained out to nanometer thickness. The film is comprised of surfactant and demulsifier molecules, and the simulations capture the pores formation in the film when a DC field is applied. The results demonstrate influence of the molecular structure of the surfactant and demulsifier, and their interactions. The subsequent section describes experimental techniques to assess the resolution of crude oil emulsions at the laboratory scale. The focus is on low-field Nuclear Magnetic Resonance (LF-NMR) which allows a determination of various emulsion features such as the droplet size distribution (DSD) and the brine profile (variation of the concentration of water with the height of the emulsion sample) and their evolution with time. Application of the technique in emulsion treatment involving chemical demulsifiers and electric field is presented. The review concludes with description of commercial industrial electrocoalecers such as the Vessel Internal Electrostatic Coalescer (VIEC) and the Compact Electrostatic Coalescer (CEC).
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Affiliation(s)
- Johan Sjöblom
- Ugelstad Laboratory, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Sameer Mhatre
- Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary T2N 1N4, Canada.
| | - Sébastien Simon
- Ugelstad Laboratory, Norwegian University of Science and Technology, 7491 Trondheim, Norway.
| | - Roar Skartlien
- Ugelstad Laboratory, Norwegian University of Science and Technology, 7491 Trondheim, Norway; Institute for Energy Technology (IFE), P.O. Box 40, N-2027 Kjeller, Norway
| | - Geir Sørland
- Ugelstad Laboratory, Norwegian University of Science and Technology, 7491 Trondheim, Norway; Anvendt Teknologi AS, Munkvollvegen 56, 7022 Trondheim, Norway
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23
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Bai P, Zhou L, Huang X, Du X. Molecular Insight into Bubble Nucleation on the Surface with Wettability Transition at Controlled Temperatures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:8765-8775. [PMID: 34259533 DOI: 10.1021/acs.langmuir.1c01121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A surface with a smart wettability transition has recently been proposed to enhance the boiling heat transfer in either macro- or microscale systems. This work explores the mechanisms of bubble nucleation on surfaces with wettability transitions at controlled temperatures by molecular simulations. The results of the interaction energy at the interface and potential energy distribution of water molecules show that the nanostructure promotes nucleation over the copper surface and causes lower absolute potential energy to provide fixed nucleation sites for the initial generation of the bubble nucleus and shortens the incipient nucleation time, as compared to the mixed-wettability or hydrophilic nanostructure surface. An investigation on more nanostructured surfaces shows that a surface (F) with a wettability transition temperature of 620.0 K has the shortest average incipient nucleation time at 1672 ps with a wall temperature of 634.3 K. The surface with tunable wettability has also a high interfacial thermal conductance at low superheats, but it may not promote the critical heat flux at high superheats. The heat-transfer performance of the smart surface is better than the plate, the hydrophobic nanostructure, and the mixed-wettability surfaces, while it is lower than the hydrophilic nanostructure surface. This proposes a new method and provides insight for promoting bubble nucleation on a surface with temperature-dependent wettability.
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Affiliation(s)
- Pu Bai
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Leping Zhou
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Xiaonuo Huang
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Xiaoze Du
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
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24
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Sun X, Yang D, Zhang H, Zeng H, Tang T. Unraveling the Interaction of Water-in-Oil Emulsion Droplets via Molecular Simulations and Surface Force Measurements. J Phys Chem B 2021; 125:7556-7567. [PMID: 34229441 DOI: 10.1021/acs.jpcb.1c04227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Water-in-oil emulsions widely exist in various chemical and petroleum engineering processes, and their stabilization and destabilization behaviors have attracted much attention. In this work, molecular dynamic (MD) simulations were conducted on the water-in-oil emulsion droplets with the presence of surface-active components, including a polycyclic aromatic compound (VO-79) and two nonionic surfactants: the PEO5PPO10PEO5 triblock copolymer and Brij-93. At the surface of water droplets, films were formed by the adsorbate molecules that redistributed during the approaching of the droplets. The redistribution of PEO5PPO10PEO5 was more pronounced than that of Brij-93 and VO-79, which contributed to lower repulsion during coalescence. The interaction forces during droplet coalescence were also measured using atomic force microscopy. Jump-in phenomenon and coalescence were observed for systems with VO-79, Brij-93, and a low concentration of Pluronic P123. The critical force before jump-in was lowest for the low concentration of Pluronic P123, consistent with the MD results. Adhesion was measured when separating water droplets with a high concentration of Pluronic P123. By correlating theoretical simulations and experimental force measurements, this work improves the fundamental understanding on the interaction behaviors of water droplets in an oil medium in the presence of interface-active species and provides atomic-level insights into the stabilization and destabilization mechanisms of water-in-oil emulsion.
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Affiliation(s)
- Xiaoyu Sun
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Diling Yang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hao Zhang
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Hongbo Zeng
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Tian Tang
- Department of Mechanical Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
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25
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Effect of electric field strength on deformation and breakup behaviors of droplet in oil phase: A molecular dynamics study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115995] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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27
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Chen Q, Lu K, Zhang Y, Qin D, Xu H, Yang C, He N. Effect of DC electric field on coalescence and breakup behaviors of binary emulsion nanodroplets. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114939] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Huang X, He L, Luo X, Xu K, Lü Y, Yang D. Non‐coalescence and chain formation of droplets under an alternating current electric field. AIChE J 2021. [DOI: 10.1002/aic.17165] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Xin Huang
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
| | - Limin He
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
- Surface Engineering Pilot Test Center China National Petroleum Corporation Daqing China
| | - Xiaoming Luo
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
- Surface Engineering Pilot Test Center China National Petroleum Corporation Daqing China
| | - Ke Xu
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
| | - Yuling Lü
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
- Surface Engineering Pilot Test Center China National Petroleum Corporation Daqing China
| | - Donghai Yang
- College of Pipeline and Civil Engineering China University of Petroleum (East China) Qingdao China
- Surface Engineering Pilot Test Center China National Petroleum Corporation Daqing China
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29
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Li N, Sun Z, Fan Y, Liu W, Guo Y, Li B, Wang Z. Understanding the breakup mechanism of a droplet under a DC electric field with molecular dynamics simulations and weak interaction analysis. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114475] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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30
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Huang X, He L, Luo X, Xu K, Lü Y, Yang D. Charge-Transfer-Induced Noncoalescence and Chain Formation of Free Droplets under a Pulsed DC Electric Field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:14255-14267. [PMID: 33206532 DOI: 10.1021/acs.langmuir.0c02371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electrocoalescence technology is an important method for the demulsification of crude oil emulsion, but its development is restricted by the short circuit caused by droplet chain formation. To reveal the formation mechanism of droplet chains, the electrocoalescence behaviors of two droplets and droplet clusters under pulsed direct current (DC) electric fields are experimentally studied. The two droplets usually successively undergo complete coalescence, partial coalescence, and noncoalescence as the electric field strength increases. The critical electric field strengths for complete coalescence under pulsed DC electric fields with different frequencies are obtained. The effects of the electric field waveform and frequency on the noncoalescence characteristics of two droplets and the stability of droplet chains are explored. The droplet chains under a high-frequency electric field are more stable and longer than those under a low-frequency electric field due to the reduction of the movement distance and the generation of daughter droplets from tip streaming. The reversal of the composition of electric forces due to charge transfer is the fundamental mechanism of noncoalescence of two droplets and chain formation in the emulsion under a pulsed DC electric field.
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Affiliation(s)
- Xin Huang
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Limin He
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Surface Engineering Pilot Test Center, China National Petroleum Corporation, Daqing 163000, China
| | - Xiaoming Luo
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Surface Engineering Pilot Test Center, China National Petroleum Corporation, Daqing 163000, China
| | - Ke Xu
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yuling Lü
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Surface Engineering Pilot Test Center, China National Petroleum Corporation, Daqing 163000, China
| | - Donghai Yang
- College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Surface Engineering Pilot Test Center, China National Petroleum Corporation, Daqing 163000, China
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31
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Sun Y, Yang D, Sun H, Wu H, Chang Q, Shi L, Cao Y, He Y, Xie T. Experimental study on the falling and coalescence characteristics of droplets under alternating electric fields. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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32
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Qi C, Li Y, Liu Z, Kong T. Electrohydrodynamics of droplets and jets in multiphase microsystems. SOFT MATTER 2020; 16:8526-8546. [PMID: 32945331 DOI: 10.1039/d0sm01357a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electrohydrodynamics is among the most promising techniques for manipulating liquids in microsystems. The electric stress actuates, generates, and coalesces droplets of small sizes; it also accelerates, focuses, and controls the motion of fine jets. In this review, the current understanding of dynamic regimes of electrically driven drops and jets in multiphase microsystems is summarized. The experimental description and underlying mechanism of force interplay and instabilities are discussed. Conditions for controlled transitions among different regimes are also provided. Emerging new phenomena either due to special interfacial properties or geometric confinement are emphasized, and simple scaling arguments proposed in the literature are introduced. The review provides useful perspectives for investigations involving electrically driven droplets and jets.
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Affiliation(s)
- Cheng Qi
- College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518000, Guangdong, China
| | - Yao Li
- College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518000, Guangdong, China
| | - Zhou Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518000, Guangdong, China.
| | - Tiantian Kong
- Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518000, Guangdong, China.
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33
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Contact time on inclined superhydrophobic surfaces decorated with parallel macro-ridges. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.124924] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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34
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Song F, Niu H, Fan J, Chen Q, Wang G, Liu L. Molecular dynamics study on the coalescence and break-up behaviors of ionic droplets under DC electric field. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113195] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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He X, Wang SL, Yang YR, Wang XD, Chen JQ. Electro-coalescence of two charged droplets under pulsed direct current electric fields with various waveforms: A molecular dynamics study. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113429] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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36
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Teo AJT, Tan SH, Nguyen NT. On-Demand Droplet Merging with an AC Electric Field for Multiple-Volume Droplet Generation. Anal Chem 2020; 92:1147-1153. [PMID: 31763821 DOI: 10.1021/acs.analchem.9b04219] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We introduce a unique system to achieve on-demand droplet merging and splitting using a perpendicular AC electric field. The working mechanism involves a micropillar to split droplets, followed by electrocoalescence using an AC electric field. Adjusting the parameters of the AC signal and conductivity of the fluid result in different merging regimes. We observed a minimum threshold voltage and a strong influence of the surfactant. We hypothesize that the merging process is caused by dipole-dipole coalescence between the daughter droplets. At the same time, adjustment of the conductivity reveals a shift in the merging regimes and can be explained with an electric circuit diagram. Size-based sorting using this merging phenomenon is subsequently demonstrated, where alternate, single, double, and triple droplets sorting were achieved. The concept presented in this paper is potentially useful for drug dispensing or multivolume digital polymerase chain reaction, as droplets of multiple sizes can be generated simultaneously.
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Affiliation(s)
- Adrian J T Teo
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Say Hwa Tan
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Nam-Trung Nguyen
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
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37
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Chen S, Wang J, Chen C, Mahmood A. Understanding the coalescence and non-coalescence of underwater oil droplets. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2019.110466] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Al-Akayleh F, Mohammed Ali HH, Ghareeb MM, Al-Remawi M. Therapeutic deep eutectic system of capric acid and menthol: Characterization and pharmaceutical application. J Drug Deliv Sci Technol 2019. [DOI: 10.1016/j.jddst.2019.101159] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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39
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Huang X, He L, Luo X, Yin H, Yang D. Non‐coalescence behavior of neutral droplets suspended in oil under a direct current electric field. AIChE J 2019. [DOI: 10.1002/aic.16739] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Xin Huang
- College of Pipeline and Civil Engineering China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
| | - Limin He
- College of Pipeline and Civil Engineering China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
- Shandong Key Laboratory of Oil & Gas Storage and Transportation Safety China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
| | - Xiaoming Luo
- College of Pipeline and Civil Engineering China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
- Shandong Key Laboratory of Oil & Gas Storage and Transportation Safety China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
| | - Haoran Yin
- College of Pipeline and Civil Engineering China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
| | - Donghai Yang
- College of Pipeline and Civil Engineering China University of Petroleum (East China), No. 66 Changjiang West Road Qingdao People's Republic of China
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40
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Zhou Y, Dong H, Yang Z, Liu Y. Break-up behavior of droplets containing chlorine salt with the same valence cation under electric field via molecular dynamics simulation. J DISPER SCI TECHNOL 2019. [DOI: 10.1080/01932691.2019.1650756] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Yu Zhou
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao, China
| | - Hang Dong
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao, China
| | - Zhuojun Yang
- College of Chemical Engineering, China University of Petroleum (East China), Qingdao, China
| | - Yonghong Liu
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao, China
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41
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Dong H, Liu Y, Zhou Y, Liu T, Li M, Yang Z. Mechanism investigation of coalescence behaviors of conducting droplets by molecular dynamics simulations. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.03.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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42
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Zhou Y, Dong H, Liu YH, Yang ZJ, Liu T, Li M. Molecular Dynamics Simulations of the Electrocoalescence Behaviors of Two Unequally Sized Conducting Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6578-6584. [PMID: 31045371 DOI: 10.1021/acs.langmuir.9b00744] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The electrocoalescence of droplets plays a crucial role in various fields. However, studies on the effects of droplet radius on the electrocoalescence behaviors of droplets have not been conducted until now. In this work, the electrocoalescence behaviors of two unequally sized conducting droplets are investigated via molecular dynamics (MD) simulations. The influences of electric field strength and droplet radius on the electrocoalescence behaviors of two unequally sized droplets are investigated. When the electric field strength increases, the contact cone angle between the droplets increases, and the two droplets are more likely to partially coalesce and bounce. When the radius of the smaller droplet between the two droplets increases at the same electric field strength, the contact cone angle, daughter droplet size, and ions in the daughter droplet increase, whereas the critical electric field strength ( Ed) for generating the daughter droplet decreases. Furthermore, the daughter droplet is ejected from the smaller droplet when the two droplets have different radii.
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43
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Datta S, Ma Y, Das AK, Das PK. Investigation of droplet coalescence propelled by dielectrophoresis. AIChE J 2018. [DOI: 10.1002/aic.16457] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Saikat Datta
- Dept. of Mechanical Engineering; Indian Institute of Technology; Kharagpur 721302 India
| | - Yanbao Ma
- School of Engineering; University of California at Merced; Merced California 95343
| | - Arup K. Das
- Dept. of Mechanical and Industrial Engineering; Indian Institute of Technology; Roorkee Uttarakhand, 247667 India
| | - Prasanta K. Das
- Dept. of Mechanical Engineering; Indian Institute of Technology; Kharagpur 721302 India
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44
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Demulsifier assisted film thinning and coalescence in crude oil emulsions under DC electric fields. Chem Eng Res Des 2018. [DOI: 10.1016/j.cherd.2018.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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45
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Chen Q, Ma J, Zhang Y, Wu C. Molecular dynamics simulation on influence of temperature effect on electro-coalescence behavior of nano-droplets. J DISPER SCI TECHNOL 2018. [DOI: 10.1080/01932691.2017.1421083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Qicheng Chen
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin, China
| | - Jie Ma
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin, China
| | - Yingjin Zhang
- School of Automation Engineering, Northeast Electric Power University, Jilin, China
| | - Chunlei Wu
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin, China
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46
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Zhou W, Zhang Z, Wang H, Yan Y, Liu X. Molecular insights into competitive adsorption of CO2/CH4 mixture in shale nanopores. RSC Adv 2018; 8:33939-33946. [PMID: 35548842 PMCID: PMC9086684 DOI: 10.1039/c8ra07486k] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 09/27/2018] [Indexed: 12/03/2022] Open
Abstract
In the present study, competitive adsorption behaviour of supercritical carbon dioxide and methane binary mixture in shale organic nanopores was investigated by using grand canonical Monte Carlo (GCMC) simulations. The model was firstly validated by comparing with experimental data and a satisfactory agreement was obtained. Then the effects of temperature (298–388 K), pressure (up to 60 MPa), pore size (1–4 nm) and moisture content (0–2.4 wt%) on competitive adsorption behaviour of the binary mixture were examined and discussed in depth. It is found that the adsorption capacity of carbon dioxide in shale organic nanopores is much higher than that of methane under various conditions. The mechanism of competitive adsorption was discussed in detail. In addition, the results show that a lower temperature is favorable to both the adsorption amount and selectivity of CO2/CH4 binary mixture in shale organic nanopores. However, an appropriate CO2 injection pressure should be considered to take into account the CO2 sequestration amount and the exploitation efficiency of shale gas. As for moisture content, different influences on CO2/CH4 adsorption selectivity have been observed at low and high moisture conditions. Therefore, different simulation technologies for shale gas production and CO2 sequestration should be applied depending on the actual moisture conditions of the shale reservoirs. It is expected that the findings in this work could be helpful to estimate and enhance shale gas resource recovery and also evaluate CO2 sequestration efficiency in shale reservoirs. Competitive adsorption behaviour of CO2/CH4 mixture in shale slit nanopores under various geological conditions was explored by molecular simulations.![]()
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Affiliation(s)
- Wenning Zhou
- School of Energy and Environmental Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
- Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry
| | - Zhe Zhang
- School of Energy and Environmental Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Haobo Wang
- School of Energy and Environmental Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
| | - Yuying Yan
- Fluids & Thermal Engineering Research Group
- Faculty of Engineering
- University of Nottingham
- Nottingham NG7 2RD
- UK
| | - Xunliang Liu
- School of Energy and Environmental Engineering
- University of Science and Technology Beijing
- Beijing 100083
- China
- Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry
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Kamp J, Villwock J, Kraume M. Drop coalescence in technical liquid/liquid applications: a review on experimental techniques and modeling approaches. REV CHEM ENG 2017. [DOI: 10.1515/revce-2015-0071] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe coalescence phenomenon of drops in liquid/liquid systems is reviewed with particular focus on its technical relevance and application. Due to the complexity of coalescence, a comprehensive survey of the coalescence process and the numerous influencing factors is given. Subsequently, available experimental techniques with different levels of detail are summarized and compared. These techniques can be divided in simple settling tests for qualitative coalescence behavior investigations and gravity settler design, single-drop coalescence studies at flat interfaces as well as between droplets, and detailed film drainage analysis. To model the coalescence rate in liquid/liquid systems on a technical scale, the generic population balance framework is introduced. Additionally, different coalescence modeling approaches are reviewed with ascending level of detail from empirical correlations to comprehensive film drainage models and detailed computational fluid and particle dynamics.
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48
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Taherian F, Marcon V, Bonaccurso E, van der Vegt NF. Vortex formation in coalescence of droplets with a reservoir using molecular dynamics simulations. J Colloid Interface Sci 2016; 479:189-198. [DOI: 10.1016/j.jcis.2016.06.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 06/19/2016] [Accepted: 06/26/2016] [Indexed: 10/21/2022]
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49
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Lu J, Fang S, Corvalan CM. Coalescence dynamics of viscous conical drops. Phys Rev E 2016; 93:023111. [PMID: 26986417 DOI: 10.1103/physreve.93.023111] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Indexed: 11/07/2022]
Abstract
When two oppositely charged drops come into light contact, a liquid meniscus bridge with double-cone geometry forms between the drops. Recent experiments have demonstrated the existence of a critical cone angle above which the meniscus bridge pinches off and the drops do not coalesce. This striking behavior-which has implications for processes ranging from the coarsening of emulsions to electrospray ionization in mass spectrometry-has been studied theoretically and experimentally for inertial liquid drops. Little is known, however, about the influence of the liquid viscosity on the critical cone angle. Here, we use high-fidelity numerical simulations to gain insight into the coalescence dynamics of conical drops at intermediate Reynolds numbers. The simulations, which account for viscous, inertial, and surface tension effects, predict that the critical cone angle increases as the viscosity of the drops decreases. When approaching the inertial regime, however, the predicted critical angle quickly stabilizes at approximately 27°, as observed in experiments.
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Affiliation(s)
- Jiakai Lu
- Transport Phenomena Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana 47907, USA
| | - Shengyang Fang
- Transport Phenomena Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana 47907, USA
| | - Carlos M Corvalan
- Transport Phenomena Laboratory, Department of Food Science, Purdue University, West Lafayette, Indiana 47907, USA
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