Chemical Engineering Commons^™

Thermal Characteristics Of Pitch Based Carbon Foam And Phase Change Materials, Kevin W. Wierschke

Theses and Dissertations

Phase-change thermal energy storage devices offer thermal control systems an option that allows a smaller heat sink to be used by absorbing the thermal energy quickly and storing it in the phase change to prevent failure of electronic components and then slowly releasing the heat to the heat sink. This paper experimentally determined the transient response of carbon foam with a phase-change material by measuring the response to a step temperature input to test samples. The transient response was recorded until steady state was reached. An analytic response was created and compared against the measured response. A simplified analytic prediction …

Comprehensive Black Liquor Droplet Combustion Studies, Leong-Teng Ip

Theses and Dissertations

Black liquor, a byproduct from pulp production, is burned in a recovery boiler to generate electricity and recover inorganic materials. Black-liquor-droplet combustion is fundamental to understanding and potentially improving recovery boiler performance. This investigation reports comprehensive experimental data collected for a suite of five liquors. All the data were collected with newly-designed laboratory equipment, several aspects of which are unique. Single droplets were suspended on a thermocouple and heated in a furnace. Simultaneous diameter (size and shape), internal and surface temperatures, surface emissivity, and mass were measured under various furnace temperatures and gas compositions. The images recorded by the cameras …

Characterization Of Fluoropolymer Powders Made By Supercritical Assisted Mixing With Crystalline Additives, Ntoh Atem-Tambe

Theses and Dissertations

This research project investigates a new technique to efficiently mix crystalline solid additives with polymers by gentle ball milling with steel balls in the presence of carbon dioxide (C02) at 17 to 30°C and 1300 to 2500 psig. As the ball milling system is agitated, the steel balls transfer mechanical energy to the fluoropolymer and additive thereby converting them to powders. C02 is added into the chamber to expand the polymer and make it amenable to impregnation by the additive. At the end of the mixing process, a free flowing powder is produced consisting of the additive coated with fluoropolymer. …

Design, Fabrication And Performance Evaluation Of An Impedimetric Urea Biosensor System, Vandana Gupta

Theses and Dissertations

An impedance bioanalyzer system comprising an in-vitro biotransducer, instrumentation and control software for the measurement of urea, potentially in blood dialysate, has been developed. The biotransducer comprises of a microlithographically fabricated interdigitated microsensor electrode (IME) onto which was cast a biorecognition layer conferred with the specificity of the enzyme urease. Urease hydrolysis of urea produces NH4+, HC03- and OH- ions that decrease the device's impedance. The temporal rate of change (kinetic) and the extent of change (equilibrium) of ion concentration were measured as the sensor's response. Five formats: [i) unPEGylated urease-containing poly(hydroxyethylmethacrylate) [p(HEMA)] hydrogel, ii) PEGylated urease-containing p(HEMA) hydrogel, iii) …

Synthesis And Characterization Of Methylene Bis (P-Cyclohexyl Isocyanate)-Poly (Tetramethyl Oxide) Based Polyurethane Elastomers, Kennard Marcellus Brunson

Theses and Dissertations

This research concerns the development and characterization of methylene bis (p-cyclohexyl isocyanate/butanediol) (HMDI/BD) based polyurethanes used in connection with surface-active anti-microbial polyurethanes. Previously studied polyurethanes having an isophorone diisocyanate/butanediol (IPDI/BD) hard block contaminated water during dynamic contact angle (DCA) analyses. This contamination by unknown species confounds results from biocidal studies and jeopardizes the use of the polyurethane as a matrix polyurethane. By contrast, polyurethanes with methylene bis (p-cyclohexyl isocyanate)/butanediol hard block showed no contamination during DCA analysis. For this reason, further study of HMDI/BD/PTMO polyurethanes was conducted. HMDI/BD polyurethanes were synthesized with 15-50wt% hard block and a soft block of …

A Finite Element Simulation Of Temperature And Material Flow In Fricton Stir Welding, Mark J. Lasley

Theses and Dissertations

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented …

A Rapidly-Converging Alternative To Source Iteration For Solving The Discrete Ordinates Radiation Transport Equations In Slab Geometry, Nicholas J. Wager

Theses and Dissertations

I present a numerical technique to solve the time independent Boltzmann Transport Equation for the transport of neutrons and photons. The technique efficiently solves the discrete ordinates equations with a new iteration scheme. I call this new scheme the angle space distribution iteration method because it combines a non-linear, high angular-resolution flux approximation within individual spatial cells with a coarse angular-resolution flux approximation that couples all cells in a spatial mesh. This shown to be an efficient alternative to source iteration. The new method is implemented using the step characteristic and exponential characteristic spatial quadrature schemes. The latter was introduced …

Rotational Molding Of Acrylonitrile-Butadiene-Styrene Polymers And Blends, Mark Grant Spencer

Theses and Dissertations

The development of acrylonitrile-butadiene-styrene (ABS) resins for use in rotational molding would provide a medium performance material, thus opening doors to new markets for the rotational molding industry. Unfortunately, ABS resins have shown serious problems during the rotational molding process, namely discoloration, bridging, and poor impact strength. It is believed that these effects are due to degradation of the carbon-carbon double bond in the butadiene, through attack by either oxygen or heat. Previous efforts have shown some success in addressing these issues. However, additional improvements are necessary to make ABS resins commercially viable to rotational molders. This study, fourth in …

Thermodynamic Property Prediction For Solid Organic Compounds Based On Molecular Structure, Benjamin T. Goodman

Theses and Dissertations

A knowledge of thermophysical properties is necessary for the design of all process units. Reliable property prediction methods are essential because reliable experimental data are often not available due to concerns about measurement difficulty, cost, scarcity, safety, or environment. In particular, there is a lack of prediction methods for solid properties. Predicted property values can also be used to fill holes in property databases to understand more fully compound characteristics. This work is a comprehensive analysis of the prediction methods available for five commonly needed solid properties. Where satisfactory methods are available, recommendations are made; where methods are unsatisfactory in …

Characterization Of Structural Changes In Thermally Enhanced Kevlar-29® Fiber, James W. Downing Jr.

Theses and Dissertations

The purpose of this exploratory investigation was to elucidate the structural mechanism accounting for the enhanced compressive properties of heat-treated Kevlar-29® fibers. A novel theory was set forth that hydrogen bond disruption and concurrent misorientation of crystallites may account for the observed augmentation of compressive properties. To examine the said theory, virgin Kevlar-29® fibers were characterized by Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) in an effort to determine if crosslinking and/or hydrogen bond disruption was responsible for the improved behavior in compression. Additionally, Kevlar-29® fibers that had been exposed to treatment temperatures of 400, 440, and 470 °C …

Slab-Geometry Molecular Dynamics Simulations: Development And Application To Calculation Of Activity Coefficients, Interfacial Electrochemistry, And Ion Channel Transport, Paul S. Crozier

Theses and Dissertations

Methods of slab-geometry molecular dynamics computer simulation were tested, compared, and applied to the prediction of activity coefficients, interfacial electrochemistry characterization, and ion transport through a model biological channel-membrane structure. The charged-sheets, 2-D Ewald, corrected 3-D Ewald, and corrected particle-particle-particle-mesh (P3M) methods were compared for efficiency and applicability to slab-geometry electrolyte systems with discrete water molecules. The P3M method was preferred for long-range force calculation in the problems of interest and was used throughout.

The osmotic molecular dynamics method (OMD) was applied to the prediction of liquid mixture activity coefficients for six binary systems: methanol/n-hexane, n-hexane/n-pentane, methanol/water, chloroform/acetone, n-hexane/chloroform, methanol/ …

The Effect Of Particle Properties On The Flow Characteristics Of Electrophotographic Powders, Joseph Pedano

Theses and Dissertations

The effect of particle size on the flow characteristics and tribo-electrical charge of dry electrophotographic (toner) powders was investigated. Toner samples, consisting of the same base formulation, but differing in particle size were prepared and studied using commercially available processing and analytical equipment. The effect of post-blending fumed silica into the toner was also investigated as part of this work. The results indicate that toner particle size has a strong effect on toner flow characteristics. The flowability measurements that were most affected by the particle size were the cohesiveness and compressibility properties of the toner powders. The data showed that …

Combustion Modeling Of Rdx, Hmx And Gap With Detailed Kinetics, Jeffrey E. Davidson

Theses and Dissertations

A one-dimensional, steady-state numerical model of the combustion of homogeneous solid propellant has been developed. The combustion processes is modeled in three regions: solid, two-phase (liquid and gas) and gas. Conservation of energy and mass equations are solved in the two-phase and gas regions and the eigenvalue of the system (the mass burning rate) is converged by matching the heat flux at the interface of these two regions. The chemical reactions of the system are modeled using a global kinetic mechanism in the two-phase region and an elementary kinetic mechanism in the gas region. The model has been applied to …

Transient Body Force Effects On The Dryout And Rewet Of A Heated Capillary Structure, Michael K. Reagan

Theses and Dissertations

A transient, one-dimensional numerical code was developed to model the liquid flow in a non-uniformly heated, axial square groove. The groove was subjected to transient body forces up to approximately 0.51 m/s² . Axial variation in meniscus levels, shear stress and heat transfer between the groove wall and the liquid, axial conduction through the liquid, evaporation and body forces were accounted for in the model. Dryout and rewet of the groove were allowed; the front location was determined using conservation of mass and linear extrapolation. A physical experiment was performed with a stainless steel plate into which eight square …

A Shock Tube Study Of Aerodynamic Heating Of Gaps In A Cylinder Subjected To Supersonic Cross Flow, Douglas D. High

Theses and Dissertations

The effects of localized aerodynamic heating in cylinder expansion gaps positioned in cross flow were investigated in a shock tube. For this study, Mach number and Reynolds number were varied from 1.04 to 1.38 and 5 x 105 to 9 x 105, respectively. The cylinder was instrumented with quick response time thermocouples positioned on the surface of the cylinder, the wall of the gap, and the gap floor. Gap aspect ratios varied from 1.23 to 3.69. Pressure gauges were used to measure wave shock speeds, pressure ratios, and transient pressure conditions. Surface temperatures were measured and converted to heat fluxes …

Static Fracture Behavior Of A Ceramic Matrix Composite At Elevated Temperatures, David M. Agins

Theses and Dissertations

This study investigated systematically the damage initiation damage progression, and failure modes of a ceramic matrix composite, Nicalon/CAS, when loaded in tension at elevated temperatures in the presence of air. A cross-ply lay-up, [0/90]_2s, was studied. The primary means of analysis were stress-strain data taken during monotonic and incremental load tests and crack density assessments. Testing was conducted at room temperature 700°C, and 850°C. The stress-strain response was consistent for monotonic and incremental loading, except for a decrease in failure load at the elevated temperatures. Initial damage progression was also consistent, but the damage leading to failure and …

Experimental Analysis Of Heat Transfer Characteristics And Pressure Drop Through Screen Regenerative Heat Exchangers, Jeffrey L. Wiese

Theses and Dissertations

This study investigated the effect on heat transfer and friction characteristics for screen regenerative heat exchangers with the screen thickness reduced by rolling. The experiments were performed on 250 and 325 mesh, 304 stainless steel screen using helium gas. Reynolds numbers, based on hydraulic radius, Re, were between 10 and 100. Both the Colburn factor, StPr^2/3, and friction factor, f, decreased as the screen thickness was reduced. A correlation was found for predicting friction factor, f. The drag coefficient per screen remained nearly unchanged for thicknesses reduced not more than 30 percent. The decrease in Colburn factor was …

A Nonlinear Three-Dimensional Micromechanics Model For Fiber-Reinforced Laminated Composites, David D. Robertson

Theses and Dissertations

In this study, a three-dimensional micromechanics model is developed. The present capabilities of the model include both unidirectional and laminated composite layups with various types of nonlinear analysis such as a thermoelastic-plastic analysis employing the Prandtl-Reuss flow relations, a thermoviscoplastic analysis using Bodner-Partom unified constitutive theory, and an interfacial damage progression scheme based on a statistical interfacial failure criteria. Such nonlinearities are critical factors during thermomechanical fatigue TMF loading of high temperature composites. Solutions were obtained and extensive comparisons performed with existing micromechanics models, finite element analysis, and experiment with excellent results. In addition, the analysis was developed to require …

Enthalpies Of Solution Of Co2 In Aqueous Methyldiethanolamine Solutions, Keith E. Merkley

Theses and Dissertations

The enthalpies of solution, H^S, of carbon dioxide in aqueous methyldiethanolamine were measured with an isothermal flow calorimeter over wide ranges of temperature, pressure, weight percent MDEA, and loading (gmole CO₂/gmole MDEA). The values of H^S (kJ/gmole CO₂) were found to be constant up to the saturation concentration of CO₂ in the aqueous solution. In addition, experimental data showed that H^S was independent of the total pressure over the solution, but linearly dependent upon both temperature and weight percent MDEA as was given by a correlation. A computer program based upon …

A Structural Study Of Some (H6-Arene)Ml2, First Row, Group Viii, Transition Metal Complexes And Their Derivatives, Stuart Kevin Janikowski

Theses and Dissertations

The structures of five organonickel compounds were determined using x-ray diffraction techniques. This study was conducted to ascertain the relationships between the compound's structures, bonding, and chemical properties. The first structural evidence for discrete complexes containing Ni-SiX3 bonds is (h6-mesitylene)Ni(SiCl3)2 and presented. The compounds (h6-toluene)Ni(SiF3)2, crystallize in space group P21/c with Z = 2. The lattice constants at 23° C are: a = 9.056(2), b = 14.426(1), c = 13. 3 0 3 ( 2) ~, {J = 10 0. 6 9 ( 1 )0 , and a = 11. 3 5 5 ( 3) , b = 11.268(4), c …

A Preliminary Investigation Of Physical-Chemical Treatment Of Slagging Gasifier Aqueous Effluent, Kirk B. Hird

Theses and Dissertations

The feasibility of treating slagging gasifier wastewater by physical-chemical means was studied. Pretreatment and treatment flow schemes were developed by using batch and continuous tests. Results were based mainly on wastewater residual total organic carbon (TOC). A treatment facility was designed and economically evaluated.

It was found that slagging gasifier wastewater is treatable by physical-chemical means using activated carbon and chemical oxidation as the two principal treatment steps. A pretreatment scheme consisting of lime addition, ammonia stripping, and recarbonation-coagu- lation was found to sufficiently purify the raw gasifier liquor so that activated carbon adsorption and chemical oxidation could be applied …

Experiments In The Explosive Pulverization Of North Dakota Lignite, James Marvin Airgood

Theses and Dissertations

During the past several years the United States Bureau of Mines and the University of North Dakota have conducted extensive investigation aimed toward the up-grading of lignite coal. These investigations include steam drying, carbonation, briquetting, and gasification of North Dakota lignite. Research work by both the Bureau of Mines and the University of North Dakota is continuing and expanding at the present time. During the past year the construction and operation of a lignite research laboratory on the University campus has been authorized by the United States government. The operation of this laboratory by the United States Bureau of Mines …