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Dehghanghadikolaei A, Abdul Halim B, Sojoudi H. Impact of Processing Parameters on Contactless Emulsification via Corona Discharge. ACS OMEGA 2023; 8:24931-24941. [PMID: 37483189 PMCID: PMC10357431 DOI: 10.1021/acsomega.3c01369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/07/2023] [Indexed: 07/25/2023]
Abstract
A contactless emulsification method is presented using corona discharge. The corona discharge forms using a pin-to-plate configuration, creating a non-uniform electric field. This results in a simultaneous electrohydrodynamic (EHD) pumping of silicone oil and an electroconvection of water droplets that accelerate and submerge inside the oil, leading to a continuous water-in-oil (W/O) emulsion formation process. The impact of the oil viscosity and corona generating AC and DC electric fields (i.e., voltage and frequency) on the characteristics of the emulsions is studied. The emulsification power consumption using the AC and DC electric fields is calculated and compared to traditional emulsion formation methods. While using the DC electric field results in the formation of uniform emulsions, the AC electric field is readily available and uses less power for the emulsification. This is facile, contactless, and energy-efficient for the continuous formation of W/O emulsions.
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Zhou CT, Yao ZZ, Chen DL, Luo K, Wu J, Yi HL. Numerical prediction of transient electrohydrodynamic instabilities under an alternating current electric field and unipolar injection. Heliyon 2023; 9:e12812. [PMID: 36699279 PMCID: PMC9868483 DOI: 10.1016/j.heliyon.2023.e12812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/26/2022] [Accepted: 01/03/2023] [Indexed: 01/13/2023] Open
Abstract
In this paper, a direct numerical simulation (DNS) of dielectric fluid flow subjected to unipolar injection under an alternating current (AC) electric field is carried out. The effect of frequency f of pulsed direct current (PDC) and AC on the transient evolution of electroconvection and their subcritical bifurcations are investigated in details. Electroconvection under PDC or AC tends to exhibit oscillating flow due to the periodic boundary condition of charge density and potential compared to the direct current (DC) case. The results demonstrate that under the PDC field, the linear criterion T c decreases with increasing frequency, while the nonlinear stability criterion T f is hardly affected. Under the AC field, a critical frequency f c = 0.0316 is found, which separates electroconvection into two typical flow regimes-periodic flow regime (f < f c ) and inhibited flow regime (f ≥ f c )-depending on whether free charges can reach the collector electrode before electric field inversion. AC-electrohydrodynamics (EHD) systems promote various flow patterns with relatively lower voltage regimes than DC-EHD systems. These mechanisms of electroconvection under the PDC/AC field offer unique possibilities for fluid flow control in biological EHD-driven flow and portable EHD applications.
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Affiliation(s)
- Chu-Tong Zhou
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China
| | - Zhen-Ze Yao
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China
| | - Di-Lin Chen
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China
| | - Kang Luo
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Corresponding author. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China.
| | - Jian Wu
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China
| | - Hong-Liang Yi
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Key Laboratory of Aerospace Thermophysics, Harbin Institute of Technology, Harbin, 150001, People's Republic of China,Corresponding author. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, People's Republic of China.
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Henrique F, Zuk PJ, Gupta A. Charging dynamics of electrical double layers inside a cylindrical pore: predicting the effects of arbitrary pore size. SOFT MATTER 2021; 18:198-213. [PMID: 34870312 DOI: 10.1039/d1sm01239h] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Porous electrodes are found in energy storage devices such as supercapacitors and pseudocapacitors. However, the effect of electrode-pore-size distribution on their energy storage properties remains unclear. Here, we develop a model for the charging of electrical double layers inside a cylindrical pore for arbitrary pore size. We assume small applied potentials and perform a regular perturbation analysis to predict the evolution of electrical potential and ion concentrations in both the radial and axial directions. We validate our perturbation model with direct numerical simulations of the Poisson-Nernst-Planck equations, and obtain quantitative agreement between the two approaches for small and moderate potentials. Our analysis yields two main characteristic features of arbitrary pore size: (i) a monotonic decrease of the charging timescale with an increase in relative pore size (pore size relative to Debye length); (ii) large potential changes for overlapping double layers in a thin transition region, which we approximate mathematically by a jump discontinuity. We quantify the contributions of electromigration and charge diffusion fluxes, which provide mechanistic insights into the dependence of charging timescale and capacitance on pore size. We develop a modified transmission circuit model that captures the effect of arbitrary pore size and demonstrate that a time-dependent transition-region resistor needs to be included in the circuit. We also derive phenomenological expressions for average effective capacitance and charging timescale as a function of pore-size distribution. We show that the capacitance and charging timescale increase with smaller average pore sizes and with smaller polydispersity, resulting in a gain of energy density at a constant power density. Overall, our results advance the mechanistic understanding of electrical-double-layer charging.
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Affiliation(s)
- Filipe Henrique
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, USA.
| | - Pawel J Zuk
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, PL-01-224 Warsaw, Poland
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Ankur Gupta
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, USA.
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Ramos A, García-Sánchez P. Editorial for the Special Issue on AC Electrokinetics in Microfluidic Devices. MICROMACHINES 2019; 10:mi10050345. [PMID: 31130659 PMCID: PMC6562559 DOI: 10.3390/mi10050345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 05/21/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Antonio Ramos
- Departamento de Electrónica y Electromagnetismo, Facultad de Física, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla, Spain.
| | - Pablo García-Sánchez
- Departamento de Electrónica y Electromagnetismo, Facultad de Física, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla, Spain.
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