Deformation of bulk dielectric fluids under corona-initiated charge injection

Mohamed, Marwan H.; Shahbaznezhad, Mohcen; Dehghanghadikolaei, Amir; Haque, Md. Ashraful; Sojoudi, Hossein

doi:10.1007/s00348-020-02951-5

Cited by 6 publications

(27 citation statements)

References 28 publications

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“…In this situation, there would be a short circuit that does not provide any EHD pumping through the liquid and consequently no emulsification process occurs. 32 , 62…”

Section: Results and Discussionmentioning

confidence: 99%

“…Silicone oil with a kinematic viscosity of 100 cSt (μ MicroLubrol, Clifton, NJ) was used for emulsion formation (see Table 1 for details). 32 To enhance the emulsification process, 1 wt % of Span 80 surfactant (Sigma-Aldrich, St. Louis, MO) was added to the silicone oil medium. After addition of the surfactant, the product was shaken gently and then it was mixed ultrasonically with a digital ultrasonic cleaner (Vevor, Los Angeles, CA) for three rounds of 15 min with 30 min intervals to allow sufficient cooling.…”

Section: Methodsmentioning

confidence: 99%

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Contactless Method of Emulsion Formation Using Corona Discharge

et al. 2022

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Electroemulsification methods use electrohydrodynamic (EHD) forces to manipulate fluids and droplets for emulsion formation. Here, a top-down method is presented using a contactless corona discharge for simultaneous emulsion formation and its pumping/collection. The corona discharge forms using a sharp conductive electrode connected to a high-voltage source that ionizes water vapor droplets (formed by a humidifier) and creates an ionic wind (electroconvection), dragging them into an oil medium. The nonuniform electric field induced by the corona discharge also drives the motion of the oil medium via an EHD pumping effect utilizing a modulated bottom electrode geometry. By these two effects, this contactless method enables the immersion of the water droplets into the moving oil medium, continuously forming a water-in-oil (W/O) emulsion. The impact of corona discharge voltage, vertical and horizontal distances between the two electrodes, and depth of the silicone oil on sizes of the formed emulsions is studied. This is a low-cost and contactless process enabling the continuous formation of the W/O emulsions.

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“…In this situation, there would be a short circuit that does not provide any EHD pumping through the liquid and consequently no emulsification process occurs. 32 , 62…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Contactless Method of Emulsion Formation Using Corona Discharge

et al. 2022

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“…The relaxation time determines whether the water droplets are able to keep their charge to travel at least half of the distance between the electrodes. 51 The whole process of migratory coalescence occurs because of the Coulombic forces. Figure 3 shows the migratory coalescence behavior of two far-away water droplets in silicone oil under pure and pulsed dc electric fields of +6 kV.…”

Section: Resultsmentioning

confidence: 99%

“…This phenomenon pushes the water droplets toward the stronger regions of the electric field. 50 , 51 , 59 To further investigate the impact of nonuniform electric field and DEP phenomena, the motion of a single water droplet under pure and pulsed dc electric fields was investigated ( Figure 5 , see also Videos S4 and S5 ).…”

Section: Resultsmentioning

confidence: 99%

“…The ions can penetrate the surface of a liquid medium if it is in their path and they can be transferred either by conduction or convection and building up a nonuniform electric field inside of the oil. 51 The presence of electric fields causes the electrocoalescence phenomenon in which the tiny water droplets in a W/O emulsion will coalesce and form a larger phase of water separated from the oil phase. As discussed earlier, increasing the strength of the electric field results in increasing the coalescence rate but an optimum range of the electric field should be utilized for the maximum efficiency.…”

Section: Introductionmentioning

confidence: 99%

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Optimum Operating Frequency for Electrocoalescence Induced by Pulsed Corona Discharge

2020

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Current oil−water separation methods require a significant power, a high processing time, and costly equipment, which typically yield low treatment efficiency. Pulsed direct current (dc) electric fields and recently nonuniform electric fields caught considerable attention in the petroleum industry research in order to address the most common oil−water separation issues such as chain formation, partial coalescence, and low efficiency in either the energy consumption or coalescence rate. Here, a contact-less charge injection method induced by corona discharge is utilized to investigate the impacts of nonuniform and pulsed dc electric fields on the coalescence of water droplets inside an oil medium. The operating process parameters were experimentally calibrated and optimized with the goal of increasing the effectiveness and energy consumption efficiency of the coalescence process. High-speed imaging and image processing techniques were used in order to investigate the effect of different active forces (i.e., dipole−dipole interaction, migratory coalescence, or electrophoresis, and dielectrophoresis) during the coalescence process. Different pulsed dc frequencies and pure dc waveforms were utilized and their impact on the coalescence of water droplets was investigated. An optimal coalescence recipe was proposed by continuous measurement of the distance, velocity, and acceleration of the coalescing water droplets. The results of this study suggest use of pulsed dc and pure dc electric fields for coalescence of water droplets in concentrated and dispersed emulsions, respectively.

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Understanding electrohydrodynamic (EHD) performance of corona discharge via particle image velocimetry (PIV)

et al. 2022

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Electrohydrodynamic (EHD) pumping through corona discharge has found many interesting applications, as it does not require any mechanical moving parts. However, understanding the EHD performance of the corona discharge is crucial for a controllable manipulation of the fluids. This study investigates the pumping performance of an in-house built corona discharge setup for inducing circular motions in the fluids. Silicone oils of different kinematic viscosities are used as the EHD fluid. The EHD performance/fluid characteristics are studied experimentally using particle image velocimetry (PIV) under different DC corona voltages and their results are verified using the continuity equation. Additionally, an analytical model is derived using the Navier–Stokes equations. A clear scaling effect of the corona voltage is seen for the EHD fluid. The EHD fluid exhibits higher velocities at high corona voltages with low perturbation frequency ($$< 3$$ < 3 Hz) which is attributed to a sloshing motion in the fluid. This naturally occurring sloshing (out-of-plane) motion can be utilized when mixing is desired in the fluid. The results of this study can be used for contact-less and controllable manipulation of dielectric fluids (i.e., silicone oils) for potential applications in emulsion formation and separation. Graphical abstract

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Deformation of bulk dielectric fluids under corona-initiated charge injection

Cited by 6 publications

References 28 publications

Contactless Method of Emulsion Formation Using Corona Discharge

Contactless Method of Emulsion Formation Using Corona Discharge

Optimum Operating Frequency for Electrocoalescence Induced by Pulsed Corona Discharge

Understanding electrohydrodynamic (EHD) performance of corona discharge via particle image velocimetry (PIV)

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