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Articles 1 - 30 of 57
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Secondary Current Distributions Using Topaz2d And Linear Kinetics, E. C. Dimpault-Darcy, Ralph E. White
Secondary Current Distributions Using Topaz2d And Linear Kinetics, E. C. Dimpault-Darcy, Ralph E. White
Ralph E. White
Secondary current density distributions are of interest
to cell designers. The purpose of this note is to illustrate
how to use an existing numerical method to determine
these distributions for cells that contain conducting and
nonconducting bodies between the main anode and cathode.
Secondary Current Distributions Using Topaz2d And Linear Kinetics, E. C. Dimpault-Darcy, Ralph E. White
Secondary Current Distributions Using Topaz2d And Linear Kinetics, E. C. Dimpault-Darcy, Ralph E. White
Ralph E. White
Secondary current density distributions are of interestto cell designers. The purpose of this note is to illustratehow to use an existing numerical method to determinethese distributions for cells that contain conducting andnonconducting bodies between the main anode and cathode.
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc–Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, Ken-Ming Yin
Galvanostatic Pulse And Pulse Reverse Plating Of Zinc–Nickel Alloys From Sulfate Electrolytes On A Rotating Disc Electrode, Branko Popov, M. Ramasubramanian, S. N. Popova, Ralph E. White, Ken-Ming Yin
Ralph E. White
Galvanostatic pulse and pulse reverse techniques have been used to study the plating of zinc–nickel alloys in the presence of nonyl phenyl polyethylene oxide. The effects of average current density, rotation speed of disc electrode and the presence of nonyl phenyl polyethylene oxide in the electrolyte on deposition of zinc–nickel alloys were evaluated. Zinc–nickel plating bath solution chemistry was studied by determining the equilibrium concentrations at various pH levels. It was found that the alloy composition was determined by solution equilibria, mass transfer of the electroactive species within the diffusion layer and by the surface coverage of nonyl phenyl polyethylene …
Mathematical Modeling Of Proton‐Exchange‐Membrane Fuel‐Cell Stacks, Dhanwa Thirumalai, Ralph E. White
Mathematical Modeling Of Proton‐Exchange‐Membrane Fuel‐Cell Stacks, Dhanwa Thirumalai, Ralph E. White
Ralph E. White
No abstract provided.
Mathematical Modeling Of A Primary Zinc/Air Battery, Z. Mao, Ralph E. White
Mathematical Modeling Of A Primary Zinc/Air Battery, Z. Mao, Ralph E. White
Ralph E. White
The mathematical model developed by Sunu and Bennion has been extended to include the separator, precipitation of both solid ZnO and K2Zn(OH)4, and the air electrode, and has been used to investigate the behavior of a primary Zn-Air battery with respect to battery design features. Predictions obtained from the model indicate that anode material utilizationis predominantly limited by depletion of the concentration of hydroxide ions. The effect of electrode thickness on anode material utilization is insignificant, whereas material loading per unit volume has a great effect on anode material utilization; a higher loading lowers both the anode material utilization and …
Parallel Plate Electrochemical Reactor Model, Ralph E. White, Mike Bain, Mike Raible
Parallel Plate Electrochemical Reactor Model, Ralph E. White, Mike Bain, Mike Raible
Ralph E. White
No abstract provided.
Governing Equations For Transport In Porous Electrodes, Pauline De Vidts, Ralph E. White
Governing Equations For Transport In Porous Electrodes, Pauline De Vidts, Ralph E. White
Ralph E. White
No abstract provided.
Predicting Shunt Currents In Stacks Of Bipolar Plate Cells With Conducting Manifolds, H. S. Burney, Ralph E. White
Predicting Shunt Currents In Stacks Of Bipolar Plate Cells With Conducting Manifolds, H. S. Burney, Ralph E. White
Ralph E. White
A method is presented for predicting shunt currents in stacks of bipolar plate cells with conducting manifolds. The method is based on the requirement that the potential drop through the solution in a manifold be large enough to force current to leave the solution and to enter the conducting manifold. The current that leaves the solution in the manifold enters the conducting manifold at the anode end of the stack and returns to the solution at the cathode end. This could cause catastrophic failure of a manifold.
The Effect Of Particle Size On The Discharge Performance Of A Nickel-Metal Hydride Cell, Jussi M. Heikonen, Harry J. Ploehn, Ralph E. White
The Effect Of Particle Size On The Discharge Performance Of A Nickel-Metal Hydride Cell, Jussi M. Heikonen, Harry J. Ploehn, Ralph E. White
Ralph E. White
We investigate the effect of particle size on the discharge performance of a nickel-metal hydride cell with a mathematical model. Electrodes with uniform as well as with nonuniform particle sizes are studied. With uniform particle size, the dependence of the particle-to-particle resistance on the particle size is taken into account. The optimal particle size depends on the discharge rate. Moreover, we show that under certain conditions it is advantageous to use a nonuniform particle size. In general, the higher the discharge current density, the more the particle size affects the electrode performance.
Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White
Parameter Estimates For A Pemfc Cathode, Qingzhi Guo, Vijay A. Sethuraman, Ralph E. White
Ralph E. White
Five parameters of a model of a polymer electrolyte membrane fuel cell (PEMFC) cathode (the volume fraction of gas pores in the gas diffusion layer, the volume fraction of gas pores in the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic conductivity of the electrolyte, and the ratio of the effective diffusion coefficient of oxygen in a flooded spherical agglomerate particle to the square of that particle radius) were determined by least-squares fitting of experimental polarization curves. The values of parameters obtained in this work indicate that ionic conduction and gas-phase transport are two …
Thermal Mathematical Modeling Of A Multicell Common Pressure Vessel Nickel-Hydrogen Battery, Junbom Kim, T. V. Nguyen, Ralph E. White
Thermal Mathematical Modeling Of A Multicell Common Pressure Vessel Nickel-Hydrogen Battery, Junbom Kim, T. V. Nguyen, Ralph E. White
Ralph E. White
A two-dimensional and time-dependent thermal model of a multicell common pressure vessel (CPV) nickel-hydrogen battery was developed. A finite element solver called PDE/Protran was used to solve this model. The model was used to investigate the effects of various design parameters on the temperature profile within the cell. The results were used to help find a design that will yield an acceptable temperature gradient inside a multicell CPV nickel-hydrogen battery. Steady-state and unsteady-state cases with a constant heat generation rate and a time-dependent heat generation rate were solved.
A Mathematical Model Of An Electrochemical Capacitor With Double-Layer And Faradaic Processes, Chuan Lin, James A. Ritter, Branko N. Popov, Ralph E. White
A Mathematical Model Of An Electrochemical Capacitor With Double-Layer And Faradaic Processes, Chuan Lin, James A. Ritter, Branko N. Popov, Ralph E. White
Ralph E. White
A mathematical model of an electrochemical capacitor with hydrous ruthenium oxide (RuO2·xH2O) electrodes including both double-layer and surface faradaic processes is developed to predict the behavior of the capacitor under conditions of galvanostatic charge and discharge. The effect of RuO2·xH2O particle size is studied and shows that the smaller the particles the better the performance because of the increased surface area per unit volume or mass. The model also predicts that the faradaic process increases significantly the energy per unit volume of the capacitor for power densities of …
Modeling Of A Nickel-Hydrogen Cell: Phase Reactions In The Nickel Active Material, B. Wu, Ralph E. White
Modeling Of A Nickel-Hydrogen Cell: Phase Reactions In The Nickel Active Material, B. Wu, Ralph E. White
Ralph E. White
No abstract provided.
Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Timothy Stoner, Narender Rana
Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition, Andrew T. Haug, Ralph E. White, John W. Weidner, Wayne Huang, Steven Shi, Timothy Stoner, Narender Rana
Ralph E. White
Sputter deposition has been investigated as a tool for manufacturing proton-exchange membrane fuel cell (PEMFC) electrodes with improved performance and catalyst utilization vs. ink-based electrodes. Sputter-depositing a single layer of Pt on the gas diffusion layer provided better performance (0.28 A/cm2 at 0.6 V) than sputtering the Pt directly onto a Nafion membrane (0.065 A/cm2 at 0.6 V) and equaled the performance of the baseline for an equivalent Pt loading. Sputter-depositing alternating layers of Pt and Nafion-carbon ink (NCI) onto the membrane did not increase the performance over the baseline as measured in amperes per centimeter squared due …
Current Distribution In A Horizon® Lead-Acid Battery During Discharge, Z. Mao, Ralph E. White, B. Jay
Current Distribution In A Horizon® Lead-Acid Battery During Discharge, Z. Mao, Ralph E. White, B. Jay
Ralph E. White
A simple mathematical model is presented and used to analyze the potential and current distributions in a HORIZON® sealed lead-acid battery. It was found that an increase in the thickness of an electrode would not enhance the discharge rate of that electrode; instead, it causes the transfer current distribution to be less uniform in the electrode. Also, the ohmic drop across the separator would decrease with a decrease in the thickness of the separator more rapidly when the thickness is small than when it is large. In addition, it was found that efficient high-capacity, high-rate electrodes must consider the electrode …
Extension Of Darby's Model Of A Hydrophylic Gas Fed Porous Electrode, Ralph E. White, M. A. Nicholson, L. G. Kleine, J. Van Zee, R. Darby
Extension Of Darby's Model Of A Hydrophylic Gas Fed Porous Electrode, Ralph E. White, M. A. Nicholson, L. G. Kleine, J. Van Zee, R. Darby
Ralph E. White
A model presented previously by one of the authors (1,2) is reviewed and extended. Aspects of this model which were not previously available in the open literature are considered, and the model is extended to include previously neglected terms in the governing differential equations, fractional reaction orders in the current density-overpotential expression, and mass-transfer coefficients to account for mass-transfer resistance of the reactants to the faces of the porous electrode. The model is used to predict quantities of interest for oxygen reduction in an acidic aqueous solution in a porous carbon electrode.
A Mathematical Model Of A Sealed Nickel-Cadmium Battery, Deyuan Fan, Ralph E. White
A Mathematical Model Of A Sealed Nickel-Cadmium Battery, Deyuan Fan, Ralph E. White
Ralph E. White
A mathematical model for the charge and discharge of a sealed nickel-cadmium (Ni-Cd) battery is presented. The model is used to study the effect of transport properties of the electrolyte and kinetic parameters of the electrode reactions on the cell performance during the charge and discharge period. The model can also be used to demonstrate the changes of cell performance during cycling. Some comparisons between model predictions and experimental results indicate that the model predictions appear to fit the experimental data well. Sensitivity analyses illustrate that the sealed nickel-cadmium battery operates under activation control. It is also shown theoretically that …
Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White
Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White
Ralph E. White
A mathematical model is presented to predict the performance of a lithium-ion battery. It includes the changes in the porosity of the material due to the reversible intercalation processes and the irreversible parasitic reaction. The model was also extended to predict the capacity fade in a lithium-ion battery based on the unwanted parasitic reaction that consumes Li+ along with the changes in the porosities of the electrodes with cycling due to the continuous parasitic side reaction. The model can be used to predict the drop in the voltage profile, change in the state of charge, and the effects of charge …
Theoretical Analysis Of Metal Hydride Electrodes: Studies On Equilibrium Potential And Exchange Current Density, Bala S. Haran, Branko N. Popov, Ralph E. White
Theoretical Analysis Of Metal Hydride Electrodes: Studies On Equilibrium Potential And Exchange Current Density, Bala S. Haran, Branko N. Popov, Ralph E. White
Ralph E. White
A theoretical model for the metal hydride electrode has been developed assuming that hydrogen diffusion in the alloy and charge-transfer at the surface control the discharge process. Theoretical equations for the dependence of equilibrium potential and exchange current density on the surface hydrogen concentration have been derived. These parameters have been used to correlate experimental data with the theoretical electrode discharge model. Analysis of both the experimental and theoretical discharge curves reveals a potential plateau determined by the magnitude of the interactions between the hydrogen in the alloy and the unhydrided metal. Neglecting these hydrogen-metal site interactions results in simulations …
Mathematical Modeling Of A Nickel-Cadmium Cell: Proton Diffusion In The Nickel Electrode, Pauline De Vidts, Ralph E. White
Mathematical Modeling Of A Nickel-Cadmium Cell: Proton Diffusion In The Nickel Electrode, Pauline De Vidts, Ralph E. White
Ralph E. White
In this paper we present a mathematical model of a sealed nickel-cadmium cell that includes proton diffusion and ohmic drop through the active material in the nickel electrode. The model is used to calculate sensitivity coefficients for various parameters in the model. These calculations show that the discharge voltage of the cell is affected mostly by the kinetics of the nickel reaction. Toward the end of discharge, proton diffusion also becomes important, because the proton diffusion process affects the active material utilization significantly. During charge, the cell voltage is mainly affected by the kinetics of the nickel reaction until the …
A Mathematical Model Of A Lithium/Thionyl Chloride Primary Cell, T. I. Evans, T. V. Nguyen, Ralph E. White
A Mathematical Model Of A Lithium/Thionyl Chloride Primary Cell, T. I. Evans, T. V. Nguyen, Ralph E. White
Ralph E. White
A one-dimensional mathematical model for the lithium/thionyl chloride primary cell has been developed to investigate methods of improving its performance and safety. The model includes many of the components of a typical lithium/thionyl chloride cell such as the porous lithium chloride film which forms on the lithium anode surface. The governing equations are formulated from fundamental conservation laws using porous electrode theory and concentrated solution theory. The model is used to predict one-dimensional, time dependent profiles of concentration, porosity, current, and potentialas well as cell temperature and voltage. When a certain discharge rate is required, the model can be used …
Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov
Development Of A New Electrodeposition Process For Plating Of Zn-Ni-X (X = Cd, P) Alloys: Permeation Characteristics Of Zn-Ni-Cd Ternary Alloys, A. Durairajan, B. S. Haran, Ralph E. White, Branko N. Popov
Ralph E. White
It is shown that an electrodeposited Zn-Ni-Cd alloy coating produced from sulfate electrolyte inhibits the discharge of hydrogen on carbon steel. The newly developed ternary alloys have approximately ten times higher corrosion resistance when compared to a Zn-Ni alloy. Hydrogen permeation characteristics of Zn-Ni-Cd alloy coatings were studied and compared with those of a bare and a Zn-Ni alloy coated steel. The transfer coefficient, a, exchange current density, io, thickness dependent adsorption-absorption rate constant, k0, recombination rate constant, k3, surface hydrogen coverage, θH, were obtained by applying a mathematical model to experimental results. Alloys obtained from baths containing higher concentration …
A Simple Method For Determining Differential Diffusion Coefficients From Aqueous Electrolyte Diaphragm Cell Data At Temperatures Below 0°C, D. M. See, Ralph E. White
A Simple Method For Determining Differential Diffusion Coefficients From Aqueous Electrolyte Diaphragm Cell Data At Temperatures Below 0°C, D. M. See, Ralph E. White
Ralph E. White
No abstract provided.
A Finite-Difference Method For Pseudo-Two-Dimensional Boundary Value Problems, Z. Mao, Ralph E. White
A Finite-Difference Method For Pseudo-Two-Dimensional Boundary Value Problems, Z. Mao, Ralph E. White
Ralph E. White
A finite-difference method is presented for solving pseudo-two-dimensional boundary-value problems. The sparse and nearly block tridiagonal properties of the matrices generated by using the finite-difference method for problems of this type are fully utilized and maintained, which yields a method that is highly efficient in the use of storage space and computation. An example shows that the central process unit time required by the method is significantly less than that required by an alternative method.
Chromium Oxides And Lithiated Chromium Oxides. Promising Cathode Materials For Secondary Lithium Batteries, Pankaj Arora, Dong Zhang, Branko N. Popov, Ralph E. White
Chromium Oxides And Lithiated Chromium Oxides. Promising Cathode Materials For Secondary Lithium Batteries, Pankaj Arora, Dong Zhang, Branko N. Popov, Ralph E. White
Ralph E. White
Chromium oxides and lithiated chromium oxides were synthesized by thermal decomposition of chromium trioxide (CrO3) at high temperatures and oxygen pressures. Synthesis temperature and pressure markedly affect the performance of these cathode materials. Higher pressures lead to a higher O/Cr ratio and fewer impurities in the final product. These materials are stable intercalation hosts for lithium, and exhibit a higher capacity than any of the prominent positive electrodes used in secondary lithium batteries. m-CrOx has a capacity of 255 mAh/g, while m-LiCrOx has a capacity of 210 mAh/g, during the first discharge. The average …
A Mathematical Model Of A Zn/Br2 Cell On Charge, M J. Mader, Ralph E. White
A Mathematical Model Of A Zn/Br2 Cell On Charge, M J. Mader, Ralph E. White
Ralph E. White
A mathematical model of a parallel plate electrochemical cell with a separator and a homogeneous bulk reaction is presented. The model is based on the Zn/Br2 redox couple and can be used as an aid for the design of an efficient rechargeable storage battery. It is shown that four independent variables exist for the system at a fixed temperature: the effective separator thickness, the residence time, the channel width, and the potential driving force. Performance criteria of interest for the Zn/Br2 battery are defined. Predictions of performance during the charging process are presented. It is shown that the …
Electrochemical Characterization Of Electronically Conductive Polypyrrole On Cyclic Voltammograms, Taewhan Yeu, Ken-Ming Yin, Jose Carbajal, Ralph E. White
Electrochemical Characterization Of Electronically Conductive Polypyrrole On Cyclic Voltammograms, Taewhan Yeu, Ken-Ming Yin, Jose Carbajal, Ralph E. White
Ralph E. White
Experimental and theoretical cyclic voltammograms for electronically conducting polypyrrole film are obtained from the identical conditions and compared to each other to characterize electrochemical behavior of the polymer. A comparison of the simulated and experimental cyclic yoltammograms shows quantitative agreement. The profiles of the dependent variables show that the switching process is governed by the availability of the counter ion to the polypyrrole electrode and the amount of electroactive sites. Sensitivity analysis shows that the double layer effects have more influence in the cyclic voltammograms than the electrokinetic effects.
Using Parameter Estimation Techniques With A Simple Model Of A Diaphragm-Type Electrolyzer To Predict The Electrical Energy Cost For Naoh Production, John Van Zee, Ralph E. White
Using Parameter Estimation Techniques With A Simple Model Of A Diaphragm-Type Electrolyzer To Predict The Electrical Energy Cost For Naoh Production, John Van Zee, Ralph E. White
Ralph E. White
Predictions of the electrical energy cost for NaOH production are determined as a function of the independent operating variables and diaphragm characterizing properties. The predictions are based on data from a statistically designed experiment, a simple model of a diaphragm-type electrolyzer, a simple model of the cell voltage losses, and parameter estimation techniques. The data were obtained over a sufficiently large range of operating conditions so that the resulting design equation may be industrially useful. The simple model of the diaphragm is based on the mass transport of the hydroxyl ion, a linear potential gradient, and is presented in terms …
Determination Of Transport And Electrochemical Kinetic Parameters Of Bare And Copper-Coated Lani4.27Sn0.24 Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Determination Of Transport And Electrochemical Kinetic Parameters Of Bare And Copper-Coated Lani4.27Sn0.24 Electrodes In Alkaline Solution, G. Zheng, Branko N. Popov, Ralph E. White
Ralph E. White
Electrochemical properties of bare and copper-coated LaNi4.27Sn0.24 electrodes were investigated in alkaline solution. The exchange current density, polarization resistance, and equilibrium potential were determined as functions of the state of charge in the electrodes. The symmetry factors for bare and copper-coated electrodes were estimated to be 0.53 and 0.52, respectively. By using a constant current discharge technique, the hydrogen diffusion coefficient in bare and coated LaNi4.27Sn0.24 was estimated to be 6.75 × 10–11 cm2/s.
Full Cell Mathematical Model Of A Mcfc, N. Subramanian, B. S. Haran, Ralph E. White, Branko N. Popov
Full Cell Mathematical Model Of A Mcfc, N. Subramanian, B. S. Haran, Ralph E. White, Branko N. Popov
Ralph E. White
A theoretical model for the molten carbonate fuel cell was developed based on the three-phase homogeneous approach. Using this model, the contribution of different cell components to losses in cell performance has been studied. In general, at low current densities, the electrolyte matrix contributed to the major fraction of potential losses. Mass transfer effects became important at high current densities and were more prominent at the cathode. Electrolyte conductivity and cathode exchange current density seemed to play a limiting role in determining cell performance. Using the model, the maximum power density from a single cell for different cell thicknesses was …