Engineering Commons^™

Experimental And Modeling Investigations Of Biomass Particle Combustion, Hong Lu

Theses and Dissertations

This investigation provides a comprehensive analysis of entrained-flow biomass combustion processes. Experimental and theoretical investigations indicate how particle shape and size influence biomass combustion rates. Experimental samples include flake-like, cylinder-like, and equant (nearly spherical) shapes with similar particle masses and volumes but different surface areas. Samples of small (less than 500 µm) particles were passed through a laboratory entrained-flow reactor in a nitrogen/air atmosphere and a maximum reactor wall temperature of 1600 K, while large samples were reacted in suspension in a single particle furnace operated at similar conditions as the entrained-flow reactor. A separately developed computer and image analysis …

Porous Fiber Formation In Polymer-Solvent System Undergoing Solvent Evaporation, Pratyush Dayal, Thein Kyu

College of Polymer Science and Polymer Engineering

Temporal evolution of the fiber morphology during dry spinning has been investigated in the framework of Cahn-Hilliard equation [J. Chem. Phys. 28, 258 (1958)] pertaining to the concentration order parameter or volume fraction given by the Flory-Huggins free energy of mixing [P. J. Flory, Principles of Polymer Chemistry (Cornell University Press, Ithaca, NY, 1953), p. 672] in conjunction with the solvent evaporation rate. To guide the solvent evaporation induced phase separation, equilibrium phase diagram of the starting polymer solution was established on the basis of the Flory-Huggins free energy of mixing. The quasi-steady-state approximation has been adopted to account for …

Methane Conversion In Pulsed Corona Discharge Reactors, Morris D. Argyle, Gui-Bing Zhao, Sanil John, Ji-Jun Zhang, Linna Wang, Suresh S. Muknahallipatna, Jerry C. Hamann, John F. Ackerman, Ovid A. Plumb

Faculty Publications

This work reports the effect of capacitance, cathode material, gas flow rate and specific energy input on methane conversion, energy efficiency and product selectivity in a co-axial cylinder pulsed corona discharge reactor. Ethan and acetylene appear to be formed from dimerization of CH3 radicals and CH radicals, respectively, while ethylene is formed mainly from the dehydrogenation of ethane. At a given power input, low capacitance with high pulse frequency results in higher methane conversion and energy efficiency than operation at high capacitance with low pulse frequency. Platinum coated stainless steel cathodes slightly enhance methane conversion relative to stainless steel cathodes, …

Transgenic Fibrinogen, William H. Velander

Department of Chemical and Biomolecular Engineering: Patents

A transgenic, non-human mammalian animal is capable of expressing a heterologous gene for human or other recombinant physiologically functional fibrinogen holoprotein or individual subunit chain polypeptides thereof or a modified or fusion fibrinogen in mammary glands of the animals and secreting the expressed product into a body fluid. Methodology employing such a mammal yields recombinant physiologically functional fibrinogens, subunit chain polypeptides thereof, and modified or fusion fibrinogens.

Breakup Of Spiral And Concentric Ringed Spherulites In Polymer Crystallization, Haijun Xu, Hao-Wen Chiu, Yoshifumi Okabe, Thein Kyu

College of Polymer Science and Polymer Engineering

Recently, the breakup of spiral and concentric ringed spherulites has been observed experimentally in isothermal crystallization of poly(vinylidene fluoride) in its blends with ethylene vinyl acetate copolymer. To elucidate the phenomenon of spiral breakup in polymer spherulites, a theoretical simulation has been undertaken in the framework of the phase field model of solidification based on time-dependent Ginzburg-Landau equations (TDGL model C) pertaining to the conserved concentration and nonconserved phase field order parameters. The concentration order parameter was described in terms of the Landau-type potential, while the crystal order parameter was expressed in terms of an asymmetric double-well potential to account …

The Decomposition Kinetics Of Solids Thermodynamic Evidence For The Enthalpy Driven Cooling Of Reaction Environment Part 2, Akwilapo D

Tanzania Journal of Engineering and Technology (TJET)

The analysis of non-isothermal kinetic data for the decomposition of calcium carbonate, CaC03 (s) ~ CaO (s) + C02 (g) in flowing nitrogen, shows that the decomposition of solids is accompanied by self-cooling/heating of the reaction environment depending on the sample mass and heating rate. The correctness of the kinetic model is established by the calculation of the enthalpy change of the reaction. This is the thermodynamic evidence of endothermic enthalpy driven cooling of the reaction environment. The enthalpy change LJH = 179.33 kJmol-1 estimated from this work for the dissociation of CaC03 is in agreement with LJH = 179.17 …

Socio-Economic Impacts Of Computer Viruses In Tanzania, M Victor

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on a research project conducted with an objective of identifying and assessing various approaches used by different computer users (Management, System Administrators and end users) in Tanzania to combat computer viruses (CVs), and to assess users' awareness level on CVs. Specifically, the study aimed at assessing the awareness level on CVs to the Tanzanian business community; analyze the socio -economic impact caused by CVs in Tanzania and; assess existing methods, capacity and limitations on controlling CVs in Tanzania. Data was collected using both questionnaires and interview from financial institutions such as NBC and BOT, and telecommunications sector …

Effectiveness Of Hot Isostatic Pressing On Healing Oxide Film Defects In Cast Aluminium Alloys, C Nyahumwa

Tanzania Journal of Engineering and Technology (TJET)

Hot isostatic pressing (hipping) of cast aluminium alloys is recognized as a means of providing improved internal soundness and mechanical properties of the castings. However, little is known about the limitations and potential benefit of the hipping process to produce reliable aluminium alloy castings containing oxide film defects due to turbulently filling of moulds. In this study, oxide film defects and fatigue lives of turbule''Zt filled unfiltered AI-7Si-Mg alloy castings have been characterised in as-cast and hipped. conditions to quantify the effectiveness of hot isostatic pressing on healing oxide film defects in the castings. The average fatigue life and fatigue …

Gasification Kinetics Of Ultrafine Coal Char Oxidation In Flame Reactions, G John

Tanzania Journal of Engineering and Technology (TJET)

Pulverized coal combustion is exceedingly complex with a  vast number of variables. In order to avoid the complications associated with the burning of coal char, a controlled study has been made of the oxidation of fine graphite in laminar methane-air flame as a contribution to the understanding of the more complex phenomena of the gasification kinetics of the char. The burning of methane is equivalent to the burning of volatiles and graphite oxidation is similar to that of coal char. Aspects of this have been simulated in experimental and computational studies of 4pm diameter graphite particle burning in methane -air …

Black Liquor Droplet Combustion And Modeling, Warren Benjamin Roberts

Theses and Dissertations

Black liquor is an intermediate product of pulp production. Recovery boilers process black liquor to recover the inorganic material for recycling in the mill and to generate electricity and steam for the paper mill. Black liquor droplet combustion rates and mechanisms dictate many aspects of recovery boiler performance. This investigation documents new experimental data on single droplet pyrolysis and combustion in a laboratory furnace that mimics many of the essential features of commercial boilers (temperature, composition, droplet size, etc.). These experiments monitored single droplets placed on a thermocouple wire and suspended from a mass balance. Simultaneous video images and pyrometry …

Crystal-Liquid Crystal Binary Phase Diagrams, P Dayal, Ra Matkar, Thein Kyu

College of Polymer Science and Polymer Engineering

We propose a new theoretical scheme for the binary phase diagrams of crystal-liquid crystal mixtures by a combination of a phase field model of solidification, the Flory-Huggins theory for liquid-liquid mixing and Maier-Saupe-McMillan (FH-MSM) model for nematic and smectic liquid crystal orderings. The phase field theory describes the crystal phase transition of anisotropic organic crystal and/or side chain liquid crystalline polymer crystals while the FH-MSM model explains isotropic, nematic and smectic-A phase transitions. Self-consistent calculations reveal several possible phase diagram topologies of the binary crystal-liquid crystal mixtures. The calculated phase diagrams were found to accord well to the reported experimental …

Poisoning And Sulfation On Vanadia Scr Catalyst, Xiaoyu Guo

Theses and Dissertations

Deactivation of titania-supported vanadia commercial SCR catalysts exposed to flue gases from both coal and coal-biomass co-firing boilers were investigated. BET surface area and average pore diameter measurements on both fresh and exposed commercial catalyst samples indicated pore plugging occurred to exposed catalyst samples. ESEM analyses showed fouling on catalyst surface, and poison deposition on both catalyst surface and inner pores. Activity assessments of commercial monolith catalysts with various exposures (time and fuel type) indicated that catalyst deactivation involves fouling, pore plugging, and poisoning. Different mechanisms may dominate depending on exposure time, catalyst properties, and combustion environment. Better controlled lab-scale …

Coversion Of Hexamine Dinitrate Into Dinitro Pentamethylene Tetramine: Follow-Up And Kinetic Model Selection, Hany A. Elazab

Chemical Engineering

Synthesis of cyclotetramethylene tetramine through the action of nitrating mixture formed of ammonium nitrate and fuming nitric acid on hexamine in presence of acetic acid, acetic anhydride and p-formaldehyde has been proven. The pathway is relatively long and hexamine dinitrate and dinitro pentamethylene tetramine (DPT) are two of the main intermediate compounds. The former was prepared, purified, and then characterized. Conversion of this compound into the latter has been followed up experimentally. Different kinetic models have been tested. The unreacted core model proved to be applicable and the surface reaction was found to be controlling.

Effect Of Co On No And N2O Conversions In Nonthermal Argon Plasma, Gui-Bing Zhao, Morris D. Argyle, Maciej Radosz

Faculty Publications

200-600 ppm of CO inhibit NO conversion in nonthermal Ar plasma, but do not produce ⁠N₂O. However, 1.01% of CO has no effect on NO conversion, but produces ⁠N₂O. In general, N₂O conversion in Ar plasma decreases with increasing CO concentration. These experimental results cannot be explained by charge transfer reactions of Ar⁺⁠. Selectivity analysis of all excited states of Ar possibly contributing to NO_x conversion without and with CO suggests that only Ar(³P₂) contributes to NO_x conversion and CO dissociation. A kinetic model of 43 …

The Antibacterial Effects Of Zinc Ion Migration From Zinc-Based Glass Polyalkenoate Cements, D. Boyd, H. Li, D. A. Tanner, Mark R. Towler, J. G. Wall

Chemical and Biochemical Engineering Faculty Research & Creative Works

Zinc-based glass polyalkenoate cements have been synthesised and their potential use in orthopaedic applications investigated. Zinc ions were released from the materials in a rapid burst over the first 24 h after synthesis, with the release rate falling below detectable levels after 7 days. Cement-implanted bone samples were prepared, and the released zinc was shown, using energy dispersive X-ray analysis, to penetrate from the cement into the adjacent bone by up to 40 μm. Finally, the cements exhibited antibacterial activity against Streptococcus mutans and Actinomyces viscosus that reflected the pattern of zinc release, with the inhibition of growth greatest shortly …

Methane Production In A 100-L Upflow Bioreactor By Anaerobic Digestion Of Farm Waste, Abhijeet P. Borole, K. Thomas Klasson, Whitney Ridenour, Justin Holland, Khursheed Karim, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Manure Waste from Dairy Farms Has Been Used for Methane Production for Decades, However, Problems Such as Digester Failure Are Routine. the Problem Has Been Investigated in Small Scale (1-2 L) Digesters in the Laboratory; However, Very Little Scale-Up to Intermediate Scales Are Available. We Report Production of Methane in a 100-L Digester and the Results of an Investigation into the Effect of Partial Mixing Induced by Gas Upflow/recirculation in the Digester. the Digester Was Operated for a Period of About 70 D (With 16-D Hydraulic Retention Time) with and Without the Mixing Induced by Gas Recirculation through an Internal …

Applications Of Room Temperature Ionic Liquids In Interfacial Polymerization, Lining Zhu

Dissertations

Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1 -alkyl-3-methylimidazolium ILs.

Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of ~20nm and a …

Synthesis Of Polymeric Nanocomposites In Supercritical Carbon Dioxide, Hongta Yang

Theses

Supereritical carbon dioxide has been of great interest in various areas of chemical science and engineering during the last decade. In this thesis, the properties of poly (methyl methacrylate) (PMMA)/silica nanocomposites with different surfactant and filler concentrations synthesized through in-situ polymerization in supercritical carbon dioxide were investigated. In addition, ferromagnetic nano-particles were synthesized and functionalized for the preparation of nanocomposites. The thermal stability and surface morphology of PMMA/iron oxide nanocomposites synthesized in supercritical carbon dioxide were first studied in the work.

The scanning electron microscopy micrographs show that higher surfactant concentration results in higher number density of polymeric nanocomposite particles …

Electrochemical Studies Of Iron-Doped Nickel Oxide Electrode For Oxygen Evolution Reaction, Jin-Zhao Huang, Zheng Xu, Hai-Ling Li, Guo-Hu Kang, Wen-Jing Wang

Journal of Electrochemistry

In this paper,the iron-doped nickel oxide thin film as anode catalyst was prepared by RF reactivesputtering method.The oxygen evolution reaction(OER) on the iron-doped nickel oxide was investigated withcyclic voltammetry,liner sweep voltammetry,polarization curves and electrochemical impedance spectroscopy.Results showthat the iron acts as active site in the film which makes the overpotential lower,and changes therate-limiting from primary discharge of OH-ions to the recombination of oxygen atom.With the increasing of ox-ygen content in flu ratio during sputtering,the electrocatalytic activities of the film increase.Iron-doped nickeloxide thin film is promising material as OER electrocatalyst for hydrogen production than the nickel electrode.The oxygen overpotential on the …

Electrochemical Behavior And Reduction Mechanism Of High Valence Silver Oxide Ag3O4 In Alkaline Solution, Yan Cheng, Ming Yu, Man-Ming Yan, Zhi-Yu Jiang

Journal of Electrochemistry

The electrochemical properties of high-valence silver oxide Ag₃O₄ in alkaline solution were investigated for the first time and the reduction mechanism of Ag₃O₄ was proposed. It can be recognized that Ag₃O₄ consists of Ag(Ⅲ) and Ag(Ⅱ)~(*). From the results of voltammetry and XRD experiments it was found that the reduction process of Ag₃O₄ was more complicated. It could be electrochemically reduced through the series reactions of Ag(Ⅲ) →Ag(Ⅱ) →Ag(Ⅰ) →Ag(O) at low discharge rate or Ag(Ⅲ) →Ag(Ⅰ) →Ag(O) at higher discharge rate.And the Ag(Ⅱ)~(*) could be reduced to …

Synthesis Of Zinc Polyhedral Microspheres And Applications In Alkaline Zn-Mno2 Battery, Hua Ma, Chun-Sheng Li, Fang-Yi Cheng, Chun-Yuan Zhou, Feng Gao, Jun Chen

Journal of Electrochemistry

The zinc polyhedral microspheres were synthesized by evaporation of pure zinc powders via a vapor-transport process.The results characterized by XRD and SEM show that the as-synthesized zinc powders are polyhedral microspheres with the diameter of 2~3 μm.The electrochemical investigation showed that the capacity of the as-assembled AA-size primary alkaline Zn-MnO₂ battery was increased to 3.14 Ah under the constant discharge current of 100 mA by using the as-deposited microspherical zinc powders as the anode active materials and γ-MnO₂ nanowires as the cathode active materials,indicating their potential application in high-energy batteries.

High Density Lifepo4/C Synthesized By Controlled Crystallization And Microwave Carbon Thermal Reduction, Chang-Ping Tang, Jie-Rong Ying, Min Lei, Wei Li, Chang-Yin Jiang, Chun-Rong Wan

Journal of Electrochemistry

The spherical FePO₄·xH₂O was prepared in the solution by controlled crystallization.The precursor FePO₄ was obtained in high temperatureceramic approach,then the high density LiFePO₄ /C was synthesized by microwave carbon thermal reduction.The structure and morphology of the materials were characterized by means of XRD and SEM techniques,and the electrochemical properties were studies by charge-discharge experiments.

Electrochemical Studies On Electrocatalytic Activity Of AuCore PtShell Nanoparticles To Methanol Oxidation, Fang Bao, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

Au_corePt_shell nanoparticles with different thicknesses were prepared by using chemical reduction method,and characterized by ultraviolet-visible spectroscopy(UV-Vis),transmission electron microscopy(TEM) and cyclic voltammetry(CV).The electrocatalytic activity of Au_corePt_shell nanoparticles with the mean diameter of 70~80 nm to methanol oxidation was investigated by cyclic voltammetry in the acid solution.The results revealed that the prepared core-shell nanoparticles were covered by Pt shell and exhibited the similar optical property and electrocatalytic activity with the normal Pt surface.Moreover,the electrocatalytic activity increased with the electrochemical sweep in the certain potential range.It might be contributed by the special loose structure of Pt shell …

Efficient, Thermally Stable, Second Order Nonlinear Optical Response In Organic Hybrid Covalent/Ionic Self-Assembled Films, Kevin E. Van Cott

Papers in Biomolecular Engineering

A covalent/electrostatic layer-by-layer self-assembly method was used to achieve polar ordering of a water soluble, reactive dye in the fabrication of nonlinear optical (NLO) films. We observed a quadratic relationship between the second harmonic intensity I2 and bilayer number for all films made with Procion Brown MX-GRN, demonstrating that the polar ordering of the chromophores is consistent in each successive bilayer. As the ionic strength of the dye deposition solution was increased to 0.5 M NaCl, the of the films increased by approximately 250% to 50 × 10-9 esu, with a corresponding average chromophore tilt angle of 38. This was …

Desulfovibrio Desulfuricans G20 Tetraheme Cytochrome Structure At 1.5 A˚ And Cytochrome Interaction With Metal Complexes, Mrunalini Pattarkine, J J. Tanner, C A. Bottoms, Y H. Lee, Judy D. Wall

Faculty Works

The structure of the type I tetraheme cytochrome c3 from Desulfovibrio desulfuricans G20 was determined to 1.5 A˚ by X-ray crystallography. In addition to the oxidized form, the structure of the molybdate-bound form of the protein was determined from oxidized crystals soaked in sodium molybdate. Only small structural shifts were obtained with metal binding, consistent with the remarkable structural stability of this protein. In vitro experiments with pure cytochrome showed that molybdate could oxidize the reduced cytochrome, although not as rapidly as U(VI) present as uranyl acetate. Alterations in the overall conformation and thermostability of the metal-oxidized protein were investigated …

Coversion Of Hexamine Dinitrate Into Dinitro Pentamethylene Tetramine: Follow-Up And Kinetic Model Selection, Hany A. Elazab

Chemical Engineering

Synthesis of cyclotetramethylene tetranitramine through the action of nitrating mixture formed of ammonium nitrate and fuming nitric acid on hexamine in presence of acetic acid, acetic anhydride and p-formaldehyde has been proven. The pathway is relatively long and hexamine dinitrate and dinitro pentamethylene tetramine (DPT) are two of the main intermediate compounds. The former was prepared, purified, and then characterized. Conversion of this compound into the latter has been followed up experimentally. Different kinetic models have been tested.

Thermal Analysis Of Adsorbed Poly(Methyl Methacrylate) On Silica, Frank D. Blum, Erin N. Young, Gregory Smith, Oliver C. Sitton

Chemistry Faculty Research & Creative Works

Modulated differential scanning calorimetry has been used to quantify the glass transitions of small, adsorbed amounts of poly (methyl methacrylate) (PMMA) on silica. While a relatively narrow, single glass transition was found for bulk PMMA, broader two-component transitions were found for the adsorbed polymer. a two-state model based on loosely bound polymer (glass transition similar to bulk) and more tightly bound polymer (glass transition centered around 156°C) was used to interpret the thermograms. on the basis of this model, the amount of tightly bound polymer was found to be approximately 1.3 mg/m 2, corresponding to a 1.1 nm thick layer. …

Numerical Aspects Of The Saft Equation Of State, Leah M. Octavio

Senior Honors Projects

Equations of states are used to model fluid behavior. At a given temperature and pressure, for example, a mixture of water and alcohol might form a liquid and vapor phase, with the vapor phase being richer in alcohol and the liquid phase richer in water. In many industrial processes, such as distillation or extraction where mixtures of different compounds need to be separated, knowing how the fluid mixture will behave at various conditions helps make the operations more efficient and economical. While many equations of state exist, they differ in their accuracy in modeling systems and in their mathematical complexity. …

An Investigation Into The Structure And Reactivity Of Calcium-Zinc-Silicate Ionomer Glasses Using Mas-Nmr Spectroscopy, D. Boyd, Mark R. Towler, R. V. Law, R. G. Hill

Chemical and Biochemical Engineering Faculty Research & Creative Works

The suitability of Glass Polyalkenoate Cements (GPCs) for orthopaedic applications is retarded by the presence in the glass phase of aluminum, a neurotoxin. Unfortunately, the aluminum ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminum-free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. However, there is no data available on the structure of these glasses. 29Si MAS-NMR, differential thermal analysis (DTA), X-ray diffraction (XRD), and network crosslink density …

Phosphate Reactions As Mechanisms Of High-Temperature Lubrication, Anitha Nagarajan, Carolina Garrido, Jorge E. Gatica, Wilfredo Morales

Chemical & Biomedical Engineering Faculty Publications

One of the major problems preventing the operation of advanced gas turbine engines at higher temperatures is the inability of currently used liquid lubricants to survive at these higher temperatures under friction and wear conditions. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 °C; hence some other form of lubrication is necessary. Vapor-phase lubrication is a promising new technology for high-temperature lubrication. This lubrication method employs a liquid phosphate ester that is vaporized and delivered to bearings or gears; the vapor reacts with the metal surfaces, generating a solid lubricious film that has proven very stable at …