Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 12 of 12
Full-Text Articles in Engineering
Mathematical Modeling Of Cathodic Protection Using The Boundary Element Method With A Nonlinear Polarization Curve, J. F. Fan, S. N. R Pakalapati, T. V. Nguyen, Ralph E. White, R. B. Griffin
Mathematical Modeling Of Cathodic Protection Using The Boundary Element Method With A Nonlinear Polarization Curve, J. F. Fan, S. N. R Pakalapati, T. V. Nguyen, Ralph E. White, R. B. Griffin
Faculty Publications
The distributions of potential and current density around a cathodically protected pipeline in seawater were determined using the boundary element technique. A nonlinear polarization curve for a low carbon steel in artificial sea water was obtained from dc-potentiodynamic measurements and was fitted for use as the boundary condition on the pipe. The program was used to evaluate cases in which one or two aluminum sacrificial anodes are used to protect a low carbon steelpipe in seawater. The results show that the number of anodes, the sizes of the anodes, and the distance between the anodes and the cathode are of …
Hydrogen Diffusion, Solubility, And Water Uptake In Dow's Short-Side-Chain Perfluorocarbon Membranes, Yu-Min Tsou, M. C. Kimble, Ralph E. White
Hydrogen Diffusion, Solubility, And Water Uptake In Dow's Short-Side-Chain Perfluorocarbon Membranes, Yu-Min Tsou, M. C. Kimble, Ralph E. White
Faculty Publications
Hydrogen gas diffusion coefficients and solubilities as well as water uptake values are reported for Dow's short-side-chain perfluoro-sulfonic and -carboxylic membranes of different equivalent weight (EW). The diffusion coefficients and solubilities were determined with an electrochemical test cell. Hydrogen solubility decreases with increasing EW in the lower EW range and tends to level off at higher EWs for both types of membranes. Both hydrogen solubility and diffusion coefficients of a sulfonic membrane with EW higher than 800 are higher than the corresponding values of a carboxylic membrane of similar EW. An unusual maximum is observed in the diffusion coefficient-EW plot …
Comparing Electrochemical Impedance Spectroscopy Methods For Estimating The Degree Of Delamination Of Organic Coatings On Steel, S. A. Mccluney, S. N. Popova, Branko N. Popov, Ralph E. White, R. B. Griffin
Comparing Electrochemical Impedance Spectroscopy Methods For Estimating The Degree Of Delamination Of Organic Coatings On Steel, S. A. Mccluney, S. N. Popova, Branko N. Popov, Ralph E. White, R. B. Griffin
Faculty Publications
Electrochemical impedance spectroscopy (EIS) was used to evaluate the degree of delamination of the epoxy primer Uniprime ED-41 electrocoated on phosphate-treated cold-rolled steel in 3.5% NaCl exposed to air. Specimens with coating thicknesses of 20.3 and 20.8 µm and surface areas of 78.5 cm2 were used. Coating parameters were obtained using a circuit-analog model. The area of delamination was estimated using several EIS parameters, including the pore resistance and the break point frequency. These values were compared to the corroded area determined visually. All methods considered exhibited a strong correlation over some or all of the range of …
Measurements Of The Fundamental Thermodynamic Parameters Of Li/Bcx And Li/Socl2 Cells, E. E. Kalu, Ralph E. White, E. C. Darcy
Measurements Of The Fundamental Thermodynamic Parameters Of Li/Bcx And Li/Socl2 Cells, E. E. Kalu, Ralph E. White, E. C. Darcy
Faculty Publications
The thermodynamic data needed to estimate the heat generation characteristics of Li/BCX and Li/SOCl2 cells were determined using two experimental techniques, equilibrium or reversible cell discharge and measurement of open circuitpotential as a function of temperature. The results obtained showed that the reversible cell potential (Er), the temperature dependence of the reversible cell potential (dEr/dT) and thermoneutral potential (Eh) of the BCX cell were respectively, Er,25oc = 3.74 V, dEr/dT = –0.857 ± 0.198 mV/K and Eh = 3.994 …
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
Faculty Publications
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.
Parameter Sensitivity And Optimization Predictions Of A Hydrogen/Oxygen Alkaline Fuel Cell Model, Michael C. Kimble, Ralph E. White
Parameter Sensitivity And Optimization Predictions Of A Hydrogen/Oxygen Alkaline Fuel Cell Model, Michael C. Kimble, Ralph E. White
Faculty Publications
A mathematical model is used to predict parameter sensitivities and optimal design parameters for a hydrogen/oxygen alkaline fuel cell. A sensitivity analysis of the various transport and electrode kinetic parameters indicates which parameters have the most influence on the predicted current density and over which range of potentials these parameters affect the fuel-cell performance the most. This information can be used to decide which parameters should be optimized or determined more accurately through further modeling or experimental studies. The effect of various design parameters on the limiting current density are investigated to determine if optimal values exist for the parameters. …
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
Faculty Publications
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 …
The Self-Discharge Of The Niooh/Ni(Oh)2 Electrode Constant Potential Study, Z. Mao, Ralph E. White
The Self-Discharge Of The Niooh/Ni(Oh)2 Electrode Constant Potential Study, Z. Mao, Ralph E. White
Faculty Publications
Hydrogen oxidation currents at a NiOOH/Ni(OH)2 electrode were measured directly at constant potentials for various hydrogen pressures and states of charge. It was found that the hydrogen oxidation current is linearly proportional to the hydrogen pressure at all electrode potentials and that the logarithm of the anodic current is a linear function of electrode potential. It was also found that hydrogen oxidation on the nickel substrate material was strongly inhibited by the presence of nickel hydroxide on the substrate surface. By comparing the currents for hydrogen oxidation and oxygen evolution on the NiOOH/Ni(OH)2 electrode and on a nickel …
Calorimetric Determination Of The Thermoneutral Potential Of Li/Bcx And Li/Socl2 Cells, E. E. Kalu, Ralph E. White, E. C. Darcy
Calorimetric Determination Of The Thermoneutral Potential Of Li/Bcx And Li/Socl2 Cells, E. E. Kalu, Ralph E. White, E. C. Darcy
Faculty Publications
Through a continuous recording of the cell voltage, heat flow, and current, the effective thermoneutral potential, Eetpof Li/BCX and Li/SOCl2 cells were determined in the temperature range, 0–60°C. The depth of discharge (DOD), temperature (T), and cell type (cell chemistry) affect the effective thermoneutral potential. The effective thermoneutral potential, Eetp differs from the classical thermoneutral potential of a cell because it takes into account the heat flow due to non-faradaic processes. The average effective thermoneutral potential at 25°C (determined by selecting the most constant region of Eetp vs. time of discharge) was 4.0 …
Reduction Of Chromium (Vi) When Solar Selective Black Chromium Is Deposited In The Presence Of Organic Additive, Branko N. Popov, Ralph E. White, D. Slavkov, Z. Koneska
Reduction Of Chromium (Vi) When Solar Selective Black Chromium Is Deposited In The Presence Of Organic Additive, Branko N. Popov, Ralph E. White, D. Slavkov, Z. Koneska
Faculty Publications
Electrochemical dc methods were used to study the reduction of chromium (VI) in the presence of organic additives. It is shown that F–, thiourea, and citric acid are essential to enable deposition of black chrome from concentrated chromic acid solutions. A new formulation of the plating bath is defined. The optimum operating conditions under which spectrally selective surface of black chrome is deposited have been determined.
Comparison Of Heat-Fin Materials And Design Of A Common-Pressure-Vessel Nickel-Hydrogen Battery, Junbom Kim, Ralph E. White
Comparison Of Heat-Fin Materials And Design Of A Common-Pressure-Vessel Nickel-Hydrogen Battery, Junbom Kim, Ralph E. White
Faculty Publications
A two-dimensional, axisymmetric, and time-dependent thermal model was developed to study the temperature behavior of the cylindrically shaped common-pressure-vessel nickel-hydrogen cell. A differential-energy-balance equation was used as the governing equation. A finite-element software package called PDE/Protran was used to solve this model. Different materials such as copper, copper beryllium, silver, and sterling silver were compared as heat-fin materials. The heat-fin geometry (thickness and height) and spacing were tested to find a design that yielded an acceptable temperature gradient inside a nickel-hydrogen cell. Pulse heat-generation rates were tested and correlated with the time-dependent heat-generation cases.
A Mathematical Model Of A Cuo/Cu Vaporvolt Cell, Makoto Kawanami, Trung V. Nguyen, Ralph E. White
A Mathematical Model Of A Cuo/Cu Vaporvolt Cell, Makoto Kawanami, Trung V. Nguyen, Ralph E. White
Faculty Publications
A new battery named "Vaporvolt"b cell is in the early stage of its development. A mathematical model of a CuO/CuVaporvolt cell is presented that can be used to predict the potential and the transport behavior of the cell during discharge.A sensitivity analysis of the various transport and electrokinetic parameters indicates which parameters have the mostinfluence on the predicted energy and power density of the Vaporvolt cell. This information can be used to decide whichparameters should be optimized or determined more accurately through further modeling or experimental studies. Theoptimal thicknesses of electrodes and separator, the concentration of the electrolyte, and …