Effect of Parameters of Pulsed Electric Field on Average Current Density through Nafion 438 Membrane in Electrodialysis Cell

The application of pulsed electric field (PEF) in electrodialysis has been proven to be efficient for a number of effects: increasing mass transfer rate, mitigation of scaling and fouling, reducing water splitting. Recently, the improvement of the membrane permselectivity for specific counterions was discovered experimentally by the group of Laurent Bazinet (N. Lemay et al. J. Memb. Sci. 604, 117878 (2020)). To better understanding the effect of PEF in electrodialysis, simulations were performed using a non-stationary mathematical model based on the Nernst–Planck and Poisson equations. For the first time, it was not only the condition used when the current density is specified but also the condition when the voltage is set. A membrane and two adjacent diffusion layers are considered. It is shown that when applying the regime used by Lemay et al. (the same current density in conventional continuous current (CC) mode and during the pulses in PEF mode), there is a significant gain in specific permselectivity. It is explained by a reduction in the membrane concentration polarization in PEF mode. In the CC mode of electrodialysis, increasing current density leads to a loss in specific permselectivity: concentration profiles in the diffusion layers and membrane are formed in such a way that ion diffusion reduces the migration flux of the preferentially transferred ion and increases that of the poorly transferred ion. In PEF mode, the concentration profiles are partially restored during the pauses when the current is zero. However, if a different condition is used than the condition applied by Lemay et al., that is, when the same average current density is applied in both the PEF and CC modes, there is no gain in specific permeability. It is shown that within the framework of the applied mathematical model, the specific selectivity depends only on the average current density and does not depend on the mode of its application (CC or PEF mode).

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Study on the Influence of Electrode Collocation to Electric Field Characteristic of ESP

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.875-877.1683 ◽

2014 ◽

Vol 875-877 ◽

pp. 1683-1686

Author(s):

Cheng Liang Jia ◽

You Shan Sun ◽

Chao Huang ◽

Wan Peng Zhang ◽

Fang Chen

Keyword(s):

Electric Field ◽

Current Density ◽

Surface Current ◽

Electrode Configuration ◽

Electrode Gap ◽

Average Current Density ◽

Surface Current Density ◽

Discharge Electrode ◽

Field Characteristic ◽

Average Current

A laboratory-scale ESP with new electrode configuration was established to investigate the electric field characteristic. Eight teeth prick line and prick plate with the length of 20mm were employed as discharge electrodes, respectively. The effects of discharge electrode type and electrode gap on V-I characteristic and surface current density were studied. The results showed that the optimum electrode gaps were 350-400mm for eight teeth line and 300-350mm for prick plate, which could obtained higher average current density and lower variance.

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Simulation of the Field Emission from a Hemisphere-on-Post Nanowire: Revision of the Fowler–Nordheim Formula in Terms of Nonuniformity and Resistance

NANO ◽

10.1142/s1793292019501054 ◽

2019 ◽

Vol 14 (08) ◽

pp. 1950105

Author(s):

Jindi Wei ◽

Gengmin Zhang ◽

Yingjie Xing ◽

Jin Yang ◽

Wensheng Zhou

Keyword(s):

Electric Field ◽

Field Emission ◽

Current Density ◽

Emission Current ◽

Average Current Density ◽

Field Emission Current ◽

Local Current ◽

Calculation Results ◽

Average Current ◽

Cross Section Formula

The electric field on a hemisphere-on-post nanowire is numerically calculated using the finite element method (FEM). The FEM calculation results show that the field is sufficiently strong for extracting a significant field emission current only in a small area at the top of the hemisphere, while the contribution to the field emission from the other part of the hemisphere and the flank side of the cylinder is negligible owing to the rapid drop of the electric field. Both the local current density at the top of the hemisphere ([Formula: see text]) and the average current density across the nanowire cross-section ([Formula: see text]) are calculated and the [Formula: see text]-to-[Formula: see text] ratio ([Formula: see text]) is introduced to reflect the nonuniformity of the field emission. An empirical formula with proper parameters that can best fit the simulation results is derived for describing the dependence of [Formula: see text] on the macroscopic electric field ([Formula: see text]). As a result, the [Formula: see text]–[Formula: see text] relationship is attained and the revision to the traditional Fowler–Nordheim (FN) formula caused by the nonuniformity of field distribution is found in both the pre-exponent part and the exponent part, so that the deviation of the FN plots from linearity often observed in experiments is partly accounted for. Moreover, the resistance at the emitter-substrate interface is shown to cause saturation in the field emission current and a downward bending of the FN plot in the high-field region.

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The efficient use of stabilizing materials in superconducting solenoids

Canadian Journal of Physics ◽

10.1139/p69-180 ◽

1969 ◽

Vol 47 (13) ◽

pp. 1401-1407 ◽

Cited By ~ 1

Author(s):

Richard Stevenson

Keyword(s):

Current Density ◽

Transient Heat Conduction ◽

Point Of View ◽

Average Current Density ◽

Initial Current ◽

Current Sharing ◽

Purity Aluminium ◽

High Purity Aluminium ◽

Average Current ◽

Composite Conductor

The problem of stability of superconducting solenoids is considered from a thermal point of view. The transient heat conduction equation for a superconducting tape clad with normal material and operated in a current sharing mode is studied, and a solution for the temperature distribution is obtained. The composite conductor is considered stable if its final temperature in the current sharing mode corresponds to the critical temperature for the initial current density in the superconductor. Using this criterion, the operating point of the superconductor and its stabilizing cladding thickness can be chosen to give a maximum average current density in the composite conductor at any field. Calculations are given for Nb3Sn tape clad with OFHC copper and with high purity aluminium.

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The study of Zn–Co alloy coatings electrochemically deposited by pulse current

Hemijska industrija ◽

10.2298/hemind111215035b ◽

2012 ◽

Vol 66 (5) ◽

pp. 749-757 ◽

Cited By ~ 1

Author(s):

Jelena Bajat ◽

Miodrag Maksimovic ◽

Milorad Tomic ◽

Miomir Pavlovic

Keyword(s):

Surface Roughness ◽

Current Efficiency ◽

Direct Current ◽

Current Density ◽

Pulse Current ◽

Pulse Plating ◽

Cathodic Current ◽

Average Current Density ◽

Corrosion Stability ◽

Average Current

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2).

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Eradication of Saccharomyces cerevisiae by Pulsed Electric Field Treatments

Microorganisms ◽

10.3390/microorganisms8111684 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1684

Author(s):

Efrat Emanuel ◽

Irina Dubrovin ◽

Ester Hanya ◽

Gad A. Pinhasi ◽

Roman Pogreb ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Electric Field ◽

Current Density ◽

Food Industry ◽

Treatment Cycle ◽

Combined Treatment ◽

Pulsed Electric Field ◽

Recovery Processes ◽

Membrane Resealing ◽

Phosphate Buffered Saline

One of the promising technologies that can inactivate microorganisms without heat is pulsed electric field (PEF) treatment. The aim of this study was to examine the influence of PEF treatment (2.9 kV cm−1, 100 Hz, 5000 pulses in trains mode of 500 pulses with a pulse duration of 10 µs) on Saccharomyces cerevisiae eradication and resealing in different conditions, such as current density (which is influenced by the medium conductivity), the sort of medium (phosphate buffered saline (PBS) vs. yeast malt broth (YMB) and a combined treatment of PEF with the addition of preservatives. When the S. cerevisiae were suspended in PBS, increasing the current density from 0.02 to 3.3 A cm−2 (corresponding to a total specific energy of 22.04 to 614.59 kJ kg−1) led to an increase of S. cerevisiae eradication. At 3.3 A cm−2, a total S. cerevisiae eradication was observed. However, when the S. cerevisiae in PBS was treated with the highest current density of 3.3 A cm−2, followed by dilution in a rich YMB medium, a phenomenon of cell membrane resealing was observed by flow cytometry (FCM) and CFU analysis. The viability of S. cerevisiae was also examined when the culture was exposed to repeating PEF treatments (up to four cycles) with and without the addition of preservatives. This experiment was performed when the S. cerevisiae were suspended in YMB containing tartaric acid (pH 3.4) and ethanol to a final concentration of 10% (v/v), which mimics wine. It was shown that one PEF treatment cycle led to a reduction of 1.35 log10, compared to 2.24 log10 when four cycles were applied. However, no synergic effect was observed when the preservatives, free SO2, and sorbic acid were added. This study shows the important and necessary knowledge about yeast eradication and membrane recovery processes after PEF treatment, in particular for application in the liquid food industry.

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Current Distribution in a Polymer Electrolyte Membrane Fuel Cell Under Flooding Conditions

ASME 2009 7th International Conference on Fuel Cell Science, Engineering and Technology ◽

10.1115/fuelcell2009-85155 ◽

2009 ◽

Author(s):

A. Jamekhorshid ◽

G. Karimi ◽

X. Li

Keyword(s):

Fuel Cell ◽

Polymer Electrolyte ◽

Current Distribution ◽

Current Density ◽

Polymer Electrolyte Membrane ◽

Operating Conditions ◽

Average Current Density ◽

Electrolyte Membrane ◽

Wide Range ◽

Average Current

Non-uniform current distribution in polymer electrolyte membrane fuel cells results in local over-heating, accelerated ageing, and lower power output than expected. This issue is very critical when fuel cell experiences water flooding. In this work, the performance of a PEM fuel cell is investigated under cathode flooding conditions. A partially flooded GDL model is proposed to study local current density distributions along flow fields over a wide range of cell operating conditions. The model results show as cathode inlet humidity and/or cell pressure increase the average current density for the unflooded portions of the cell increases but the system becomes more sensitive to flooding. Operating the cell at higher temperatures would lead to higher average current densities and the chance of system being flooded is reduced. In addition, higher cathode stoichiometries prevent system flooding but the average current density remains almost constant.

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Modeling, parametric analysis and optimization of an anode-supported planar solid oxide fuel cell

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214568823 ◽

2015 ◽

Vol 229 (17) ◽

pp. 3125-3140 ◽

Cited By ~ 3

Author(s):

Mehdi Borji ◽

Kazem Atashkari ◽

Nader Nariman-zadeh ◽

Mehdi Masoumpour

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Temperature Difference ◽

Current Density ◽

Solid Oxide ◽

Oxide Fuel ◽

Multi Objective Optimization ◽

Average Current Density ◽

Multi Objective ◽

Average Current

Solid oxide fuel cell is a promising tool for distributed power generation systems. This type of power system will experience different conditions during its operating life. The present study aims to simulate mathematically a direct internal reforming planar type anode supported solid oxide fuel cell considering mass and energy conservation equations along with a complete electrochemical model. Two main reactions, namely water–gas shift reaction and methane steam reforming reaction, are considered as two dominant reactions occurring in a fuel cell. Such a model may be employed to examine the effect of different operating conditions on main solid oxide fuel cell parameters, such as temperature gradients, power, and efficiency. Furthermore, using such mathematical model, a multi-objective optimization procedure can be applied to determine maximum cell efficiency and output power under constraints such as the allowable temperature difference and limited operating potential. The selected design variables are air ratio, fuel utilization, average current density, steam to carbon ratio, and pre-reforming rate of methane. It has been revealed that any increase in pre-reforming rate of methane and steam to carbon ratio of the entering fuel will lead to efficiency penalty and more uniform temperature distribution along the cell. In addition, the more average current density increases, the less electric efficiency is achieved, and on the other hand, the more temperature difference along the cell is seen. Besides, it is shown that some interesting and important relationships as useful optimal design principles involved in the performance of solid oxide fuel cells can be discovered by Pareto based multi-objective optimization of the mathematically obtained model representing their electric performance. Such important optimal principles would not have been obtained without the use of both mathematical modeling and the Pareto optimization approach.

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Preparation of Ni-ZrO2-CeO2 Nanocomposite Coatings by Pulse Electrodeposition

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.395-396.174 ◽

2013 ◽

Vol 395-396 ◽

pp. 174-178 ◽

Cited By ~ 1

Author(s):

Yang Yang Xu ◽

Yu Jun Xue ◽

Fang Yang ◽

Chun Yang Liu ◽

Ji Shun Li

Keyword(s):

Current Density ◽

Smooth Surface ◽

Pulse Current ◽

Nanocomposite Coating ◽

Pulse Electrodeposition ◽

Nanocomposite Coatings ◽

Duty Ratio ◽

Average Current Density ◽

Average Current ◽

Surface Morphologies

Ni-ZrO2-CeO2nanocomposite coatings were prepared by pulse electrodeposition. The effect additions of ZrO2and CeO2nanoparticles, average current density, duty ratio and frequency of pulse current on nanoparticle contents of Ni-ZrO2-CeO2nanocomposites were studied. The surface morphologies and microhardness of different nanocomposite coatings (Ni-ZrO2, Ni-CeO2, Ni-ZrO2-CeO2) were analyzed. The results show that, with the average current density, duty ratio and frequency increased, the nanoparticle contents increased at first and then decreased. Compared with Ni-ZrO2and Ni-CeO2, the surface morphology of Ni-ZrO2-CeO2nanocomposite coating showed better smooth surface and more compact microstructure, the microhardness was also higher.

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Effect of Pulse Electrodeposition Parameters on Microhardness of Ni-ZrO2-CeO2 Nanocomposite Coating

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1049-1050.31 ◽

2014 ◽

Vol 1049-1050 ◽

pp. 31-34

Author(s):

Shuang Shuang Liu ◽

Yu Jun Xue ◽

Yang Yang Xu ◽

Ji Shun Li

Keyword(s):

Composite Coating ◽

Current Density ◽

Pulse Current ◽

Pulse Frequency ◽

Nanocomposite Coating ◽

Pulse Electrodeposition ◽

Duty Ratio ◽

Positive Duty ◽

Average Current Density ◽

Average Current

Ni-ZrO2-CeO2 nanocomposite coating was prepared by pulse electrodeposition. The effect of addition of ZrO2 and CeO2 nanoparticles, average current density, duty cycle and pulse current on microhardness of Ni-ZrO2-CeO2 nanocomposites were studied. The results show that microhardness of nanocomposite is increased at first and then decreased with the increasing additive amounts of two kinds of nanoparticles. With increasing reverse the average current density, the microhardness of the composite coating increases. Also, the microhardness of nanocomposite fall with the increasing of pulse frequency. With the positive duty ratio increasing, the microhardness of the composite coating increase at first and then decreased, but with the increasing of the reverse duty ratio, the microhardness of nanocomposite coating is gradually decreased.

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