Engineering Commons^™

Current Distribution In A Horizon® Lead-Acid Battery During Discharge, Z. Mao, Ralph E. White, B. Jay

Faculty Publications

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 …

Impedance Analysis For Oxygen Reduction In A Lithium Carbonate Melt, Bhasker B. Davé, Ralph E. White, Supramaniam Srinivasan, A. John Appleby

Faculty Publications

Oxygen reduction on a smooth gold electrode in a pure lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The impedance data were analyzed using the Randles-Ershler equivalent circuit to determine parameters such as the charge-transfer resistance, Warburg coefficient, double-layer capacity, and uncompensated electrolyte resistance. The parameters estimated by complex plane plots and a complex nonlinear least squares method are in good agreement. Cyclic voltammetric measurements showed that oxygen reduction in a lithium carbonate melt is very rapid. A mass transfer parameter, DC₀, estimated by the cyclic voltammetry concurred withthat calculated by the electrochemical …

Electrochemical Characterization Of Electronically Conductive Polypyrrole On Cyclic Voltammograms, Taewhan Yeu, Ken-Ming Yin, Jose Carbajal, Ralph E. White

Faculty Publications

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.

A Modified Electrochemical Process For The Decomposition Of Hydrogen Sulfide In An Aqueous Alkaline Solution, Z. Mao, A. Anani, Ralph E. White, S. Srinivasan, A. J. Appleby

Faculty Publications

An electrochemical process for the decomposition of hydrogen sulfide into its constituents in an aqueous alkaline solution is presented. It essentially consists of presaturation of an alkaline scrubber solution with H₂S. Thereafter, partial neutralization of the presaturated solution provides not only the necessary mass balance for electrolysis, but also creates the optimum conditions under which passivation of the anode, as well as side chemical and electrochemical reactions, are minimized. Finally, the electrolysis stage of the process leads to precipitation of crystalline sulfur at the anode and evolution of hydrogen at the cathode. Regeneration of the alkaline solution via …

A Mathematical Model Of The Self-Discharge Of A Ni-H2 Battery, Z. Mao, Ralph E. White

Faculty Publications

A simple mathematical model is presented and used to characterize the self-discharge of a nickel oxyhydroxide(NiOOH) electrode in a hydrogen environment. This model includes diffusion of dissolved hydrogen in an electrolyte film which covers a flooded electrode, electrochemical oxidation of hydrogen, reduction of nickel oxyhydroxide, and changes of surface area and of porosity of the electrode during the self-discharge process. Although the self-discharge process is complicated, the predictions of the model are consistent with experimental results reported in the literature, which include linear relationships between the logarithm of hydrogen pressure and time and between the logarithm of the capacity remaining …

In Situ Degradation Of Polyhalogenated Aromatic Hydrocarbons By Electrochemically Generated Superoxide Ions, E. E. Kalu, Ralph E. White

Faculty Publications

The reduction of dioxygen in aprotic media yields superoxide ions which react with polyhalogenated aromatic hydrocarbons by nucleophilic substitution. The degradation of hexachlorobenzene to bicarbonates and chlorides using in situ generated superoxide ions was carried out at room temperature in a flow cell system equipped with a gas fed, porous electrode. The effects of current, electrolyte flow, and aprotic media on the extent of degradation of hexachlorobenzene are presented.

A Mathematical Model Of A Hydrogen/Oxygen Alkaline Fuel Cell, Michael C. Kimble, Ralph E. White

Faculty Publications

A mathematical model of a hydrogen/oxygen alkaline fuel cell is presented that can be used to predict polarization behavior under various potential loads. The model describes the phenomena occurring in the solid, liquid, and gaseous phases of the anode, separator, and cathode regions, assuming a macrohomogeneous, three-phase porous electrode structure. The model calculates the spatial variation of the partial pressures of oxygen, hydrogen, and water vapor, dissolved oxygen and hydrogen concentrations, electrolyte concentration, and the solid- and solution-phase potential drops. By developing a complete model of the alkaline fuel cell, the interaction of the various transport and kinetic resistances can …

Mathematical Modeling Of A Nickel-Cadmium Battery: Effects Of Intercalation And Oxygen Reactions, Deyuan Fan, Ralph E. White

Faculty Publications

Extensions are presented for a previously published (1) mathematical model of a nickel-cadmium (Ni-Cd) cell. These extensions consist of intercalation thermodynamics for the nickel electrode and oxygen generation and reduction reactions during charge and overcharge. The simulated results indicate that intercalation may be important in the nickel electrode and that including the oxygen reactions provides a means of predicting the efficiency of the cell on charge and discharge.

Effect Of Ohmic, Mass-Transfer, And Kinetic Resistances On Linear-Sweep Voltammetry In A Cylindrical-Pore Electrode, John W. Weidner, Peter S. Fedkiw

Faculty Publications

Extracting quantitative kinetic information from linear-sweep voltammograms (LSV) on porous electrodes is more difficult than on planar electrodes since the electrode surface is not uniformly accessible to the bulk supply of reactant or the counterelectrode. We present here a means to account for the effect of ohmic, mass-transfer, and kinetic resistances on LSV by modeling a pore in a porous matrix as a cylindrical-pore electrode, and solving the mass and charge conservation equations in the context of this geometry for the simply redox reaction O + ne^– <=> R where both O and R are soluble species. Both analytical …

Observation Of The Visible Absorption Spectrum Of H2o+, Biswajit Das, John W. Farley

Electrical & Computer Engineering Faculty Research

The Ã ² Ã₁–X̃ ² B̃₁ system of H₂O⁺ has been observed, using laser absorption spectroscopy in a velocity‐modulated discharge. A total of 78 transitions between 14 794 and 15 475 cm⁻¹ have been observed with an uncertainty (1 SD) of 0.02 cm⁻¹, including 76 transitions in the (0,7,0)–(0,0,0) band and 2 in the (0,8,0)–(0,0,0) band. This species is important for cometary astronomy, and intriguing for molecular physics because of its prominent Renner–Teller interaction. Careful measurements were made of the relative intensities of the absorption lines, …

Methods Of Measuring The Solubility And Viscosity Of Lubricating Oil/Refrigerant Mixtures At High Discharge Pressures And Temperatures, Nolan Van Gaalen

Faculty Work Comprehensive List

The design and construction of a test facility and methodology for measuring the solubility and viscosity of lubricating oil/refrigerant mixtures at high pressures and temperatures are described. An auxiliary charging system, developed to provide precisely measured quantities of oil and refrigerant to the test facility, is also presented. The test facility was developed under the sponsorship and supervision of ASHRAE which funded this research project (RP-580);The solubility, viscosity and density of mixtures of R-22 and of R-502 with commonly used 150 SUS lubricants have been measured by using this facility. Specifically, results for liquid mixtures of 10% to 40% refrigerant …

Biodegradation Of Hexachlorocyclohexane In Sand And Wastewater Using Immobilized Phanerochaete Chrysosporum, Ajaykumar C. Gami

Theses

The present study was carried out in order to assess the ability of Phanerochaete chysosporium to degrade lindane (hexachlorocyclohexane) in sand as well as in water. It was found that the fungus is immobilized on saw dust, it is able to degrade lindane in a packed-bed reactor configuration, with a first-order rate constant of 0.00066min^-1. The fungus is also able to degrade lindane in sand. As with the packed-bed reactor, a supplemental carbon source (glucose) is required. In this study it was found that a glucose concentration of 20 gm/kg of sand, and 40% w/w moisture content, give …

Preparation And Testing Of Novel Blocked Isocyanate Dental Adhesives Based Upon Hydroxyhexylmethacrylate, Yunwen Ye

Theses

A new kind of dental adhesive, O-Chlorophenol-TDI-HEMA-Pentaerythritol (TDI), was studied under long term conditions. The test was done in human third molar teeth which had been extracted 7 days to 6 months. Both citric acid and non citric acid pre-treatments were used on dentin surfaces. Based on Causton's[9] mineralizing solution pre-treatment method, we have used 3 kinds of mineralizing solutions, ITS, 0.5% CaCl2, NaF, as pre-treatment solutions. There were no significant differences between the citric acid and non citric acid pre-treatment. The ITS mineralizing solution pre-treatment caused a large increase in bond strength. The average bond strength of 1791 psi …

Evaluation Of Rates Constants In An Isothermal Turbular Reactor, Yu-Hsin Lin

Theses

To view upon an incompressible laminar-flow fluid in fully developed in a plug reactor, in which a layer of catalyst coated on the inside surface of this reactor. Two kinds of reaction will occur : one is bulk ( homogeneous ) reaction, i.e., the reaction of reactants themselves; another is a first-order irreversible catalyst ( heterogeneous ) reaction, i.e., the reaction of reactants and catalysis.It is apparent that two reactipn rate constants, Κ_b for the homogeneous reaction and Κ_ω for the heterogeneous reaction, will be caused because of these two reactions

One partial differential equation after working of …

Method Of Processing Superconducting Materials And Its Products, Kenji Okazaki, Robert J. De Angelis, Charles E. Hamrin Jr.

Chemical and Materials Engineering Faculty Patents

A method for fabricating relatively dense monoliths of superconducting material and relatively dense composite monoliths of superconducting material and binder material. The method includes the steps of placing the material to be processed in a die. A relatively high pressure is then applied to the material. Substantially simultaneously, an electrical discharge is applied to the material. The discharge is of a relatively high voltage and current density to provide sharp bonding while maintaining the superconducting properties of the material in the monolith product. A product fabricated by the present method is also described.

Dendrite Tip Radii In Directionally Solidified Pb-8.4-Atmospheric-Percent-Au, Surendra N. Tewari

Chemical & Biomedical Engineering Faculty Publications

The cell/dendrite tip radii in directionally solidified Pb-8.4at.%Au have been investigated as a function of the growth speed and thermal gradient in the liquid at the tip. Dendrite growth models are not able to predict quantitatively the tip radii and tip compositions separately because of the occurrence of thermosolutal convection during growth. However, the relationship between the destabilizing solutal gradient, the stabilizing thermal gradient and the capillarity at the tip assumed using the ''marginal stability'' criterion is supported by the experimental data.

Effect Of Refining On The Brightness Of Softwood Ctmp And Tmp Pulps, Ashok Kumar Mishra

Masters Theses

The main objective of this study was to investigate the effect of refining on the brightness of softwood chemithermomechanical (CTMP) and thermomechanical (TMP) pulps. Seven different pulps were refined using a laboratory Valley beater. Brightness, opacity, tensile index, TEA, and fines content of these pulps were determined at four different freeness levels. Scattering (s) and absorption (k) coefficients of these pulps were calculated. One-way analyses of variance (ANOVA) were applied to determine the significance of change in brightness.

Changes in s-values were significantly affected by fiber morphology of different wood species. Refining increased the k-values of the pulps. When the …

Modeling A Fuel Rich Premixed Laminar Methane Flame Oh, Ch, Nh, Cn Profiles, Including Prompt No, Md. Hasan Ul Karim

Theses

A detailed reaction mechanism based upon fundamental thermochemical kinetic principles has been developed to describe the concentration profiles of OH, CH, NH, CN, and NO including prompt NO radicals in laminar flow, fuel rich methane flames as well as flames doped with 700 ppm ammonia. A one dimensional laminar flat flame code which incorporated diffusion, and the detailed reaction mechanism was used to predict the radical concentration profiles from the model. These calculated values are compared to experimental data of Dean (1984).

The model consist of two reaction subsets, hydrocarbon oxidation set and an ammonia oxidation set. The reactions most …

Recycling: Separation Of Major Thermoplastics From Postconsumer Plastics Stream, Rafael A. Rodriguez

Theses

The complete process for separating Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polyvinyl Chloride (PVC), Polypropylene (PP), Polystyrene (PS), Polyurethane (PU), and Polyethylene Terephthalate (PET) from a mixture of postconsumer plastics materials was presented. The driving forces considered to achieve separation were different densities and selective solubility of plastics in specific solvents.

The proposed process separates Polyurethane and Polystyrene by using aqueous solutions of different densities. On the other hand, the other five plastics are separated using solvents.

Diagrams showing streams and plastics separation in each unit were discussed. Individual material balances for each step were performed for a …

Tests For Positive Jumps In The Intensity Of A Poisson Process: A Power Study, Max Engelhardt, James M. Guffey, F. T. Wright

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Tests are considered for the hypothesis of a constant intensity against the alternative of an intensity which increases with time in a nonhomogeneous Poisson process. Attention is focused on step-function alternatives and tests designed for such alternatives. One application is testing for abrupt changes in equipment following scheduled overhauls. The authors recommend the order-restricted likelihood-ratio test over an ordered chi-square test for such situations, provided the points at which jumps can occur are known. Otherwise, they recommend the test based on the Laplace statistic. The performance of these tests is evaluated for smooth alternatives, with the result that the smallest …

Investigation On The Use Of Ethyl Acetate As Solvent For Seed Oil Extraction, E. L. Rivera Porras

Tanzania Journal of Engineering and Technology (TJET)

An investigation on the use of ethyl acetate as a solvent for the seedoil industry was carried out. As hexane is the most used solvent in extraction of oil from seeds, the study focuses on the comparison of the two solvents. The parameters studied were: contact time between solvent and seed cake, temperature of the solvent, quantity of solvent used for extraction and type of solvent. The results are presented on a relative basis where hexane is given a factor of 100. From the results obtained it can be seen that ethyl acetate is in general a better solvent than …

Mass Transfer Of Hazardous Organic Compounds In Soil Matrices Relevant To Thermal Desorption/Incineration, Jong-In Dong

Dissertations

Soils contaminated with hazardous organic compounds have been known to threaten human health both directly through various contact mechanisms and indirectly through leaching or transfer to the food chain. Thermal desorption of contaminated soil matrices with secondary treatment of the effluent gases (collection, incineration, etc) is one of most feasible and developing technologies for cleaning of contaminated soils. There is, however, little known about the mass transfer principles of organic contaminants through the heated soil matrices. The objectives of this study is, therefore, to learn and understand details of the mass transfer processes of organic compounds in these soil matrices. …

Mathematical Modeling And Computer Simulations Of Biodenitrification In Batch And Sequencing Batch Reactors, Sugata Sanyal

Theses

Mathematical models have been derived for describing biodegradation of ni¬trate and nitrite in an anaerobic environment. Monod model for nitrate and Andrews model for nitrite were used as kinetic models. Experimental data from literature suggest that nitrate is not an inhibitory substance, while nitrite is not only inhibitory but it may also have a toxic effect on the biomass. The models were brought in dimensionless form in order to reduce the number of parame¬ters. Biodegradation was mathematically described for a batch, and a sequencing batch mode of operation. Computer programs were developed for numerically simulating the process. Some of the …

Biodegradation Of Phenol By Two Competing Microbial Species In A Sequencing Batch Reactor, Yoo-Suk Ko

Theses

Biodegradation of a single pollutant by two competing microbial species has been mathematically described for the case where a sequencing batch reactor is used. The model has been solved numerically to predict the behavior of the reactor under different operating conditions and for different kinetic expressions for biodegradation.

Experiments were performed to verify the predictions of the model. Serratia marcescens (ATCC 17991) and Pseudomonas putida (ATCC 31800) were the species used. Experiments were first performed in order to reveal the kinetics of biodegradation for each individual species. The biodegradable substance used was phenol, which was the sole carbon source in …

Multiphase Solid-Liquid-Liquid Mixing In Stirred Tanks, George R. Deritter

Theses

A large number of investigations can be found in the literature which examine the effect of mixing parameters in both solid-liquid and liquid-liquid systems. However, very little is currently available for solid-liquid-liquid systems. It is the intent of this study to look at the various parameters affecting the point of complete dispersion for a liquid and the point of complete suspension for a solid phase, in a three phase liquid-liquid-solid system.

Phase-Separation Dynamics Of Polycarbonate Polymethyl Methacrylate Blends. I. Temperature Jumps Into An Immiscibility Loop, Dong-Soo Lim, Thein Kyu

College of Polymer Science and Polymer Engineering

No abstract provided.

Phase-Separation Dynamics Of Polycarbonate Polymethyl Methacrylate Blends. Ii. Temperature Jumps Above An Immiscibility Loop, Thein Kyu, Ds Lim

College of Polymer Science and Polymer Engineering

No abstract provided.

Heat And Momentum Transfer Analogies For The Transitional And Turbulent Flow Of A Non-Newtonian Power-Law Fluid In A Heated Pipe, Prapat Wangskarn, Bahman Ghorashi

Chemical & Biomedical Engineering Faculty Publications

A model is proposed for the transfer of heat to non-Newtonian power-law fluids flowing in heated horizontal pipes. Comparisons with the existing models, based on the absolute-percent-arithmetic-average-deviation and the percent-standard-deviation, show that under the transitional and turbulent flow regimes the proposed correlation fits the experimental data more accurately over a wide range of flow behavior index and there are no restrictions for its use when applied to pseudoplastic fluids.

A Numerical Solution For The Turbulent Flow Of Non-Newtonian Fluids In The Entrance Region Of A Heated Circular Tube, Prapat Wangskarn, Bahman Ghorashi, Rama Subba Reddy Gorla

Chemical & Biomedical Engineering Faculty Publications

Numerical solutions of conservation equations are obtained for turbulent flow of non-Newtonian fluids in a circular tube. The forward marching procedure of Patankar and Spalding^1 was implemented in order to obtain the simultaneous development of the velocity and temperature fields by using the apparent viscosity of fluids. Prandtl's mixing length concept is used to determine the apparent turbulent shearing stress. Furthermore, local and average Nusselt numbers are obtained in the entrance region, as well as in the fully developed region. For the case of the fully developed region, values of the Nusselt numbers …

Dioxin Formation : Thermodynamics And Reaction Pathways During The Oxidation/Incineration Of Chloroaromatics, Sanjiv Narendra Patel

Theses

Enthalpy, entropy and heat capacity property estimation for cyclic molecules using Benson's group additivity method require the use of ring correction terms. Ring correction terms are estimated from the thermodynamic properties of the cyclic molecule being considered. In the absence of litera¬ture values a procedure is proposed to predict these thermodynamic values.

Benson's Group additivity method does not fully account for the interactions between bulky group or atom substituents on the aromatic ring. In order to have accurate thermodynamic properties for these compounds, a data base is generated with ortho, meta and Para interactions for (Cl-Cl), (Cl-OH), (OH-OH), (CH_{3 …}