Engineering Commons^™

Statistical Methods For Kinetic Modeling Of Fischer Tropsch Synthesis On A Supported Iron Catalyst, Brian L. Critchfield

Theses and Dissertations

Fischer-Tropsch Synthesis (FTS) is a promising technology for the production of ultra-clean fuels and chemical feedstocks from biomass, coal, or natural gas. Iron catalysts are ideal for conversion of coal and biomass. However, precipitated iron catalysts used in slurry-bubble column reactors suffer from high attrition resulting in difficulty separating catalysts from product and increased slurry viscosity. Thus, development of an active and selective-supported iron catalyst to manage attrition is needed. This thesis focuses on the development of a supported iron catalyst and kinetic models of FTS on the catalyst using advanced statistical methods for experimental design and analysis. A high …

Investigation Of Flow And Microstructure In Rheometric And Processing Flow Conditions For Liquid Crystalline Pitch, Santanu Kundu

All Dissertations

A fundamental understanding of flow and its influence on the microstructure is required to obtain carbon materials with desired properties. The objective of this research was to investigate the flow and microstructural behavior of a synthetic mesophase pitch (AR-HP) in rheometric and processing flow conditions. In addition, simulation studies were performed to establish a frame work for modeling the flow behavior of this complex material in different flow situations.
The steady-shear viscosities obtained from a cone-plate rheometer during increasing rate-sweep experiments exhibited a shear-thinning region (Region I) with a slope of about -0.2 and a plateau (Region II) region. The …

Computer Modeling Of Tennessee Valley Authority’S Coal Based Power Plant At Kingston To Predict The Effluent To Emory River, Bratendu Bagchi

Doctoral Dissertations

In the wake of stringent environmental regulations, this research studies ash pond discharge to the river by Kingston Power plant. Currently 1296 MGD of fresh water from the Emory river via plant intake is used in condenser cooling. 40 MGD of ash sluice water containing ammonium compounds, mercury compounds, phosphates, Arsenic, Selenium, etc, is discharged to the plant intake via the ash pond for recycle back as sluice water into the plant. Ammonia slip from SCR unit is responsible for the ammonia and mercury comes from the coal. The research addresses the methodology to predict pollutants in the ash pond …

Lignin Composites With Phenol-Acrylates Cured By Electron Beam, Seth N. Bowman

Masters Theses

As the major by-product of the pulp and paper industry, determining a use for lignin represents a key priority to almost any bio-materials research organization. The purpose of this study is to investigate the interaction with and effects of lignin within phenol- acrylate composites cured by electron beam, characterizing changes to both physical and chemical properties. In order to more fully characterize the effects of lignin, results of pure lignin as well as cellulose samples subjected to electron beam radiation and tested by FT-IR are presented. For the composite material, results of both DMA and FT-IR spectroscopy will be presented. …

Production Of Ethanol From Hardwood, Jay Mitchell

Electronic Theses and Dissertations

Diminishing crude oil and natural gas supplies, along with concern about greenhouse gas are major driving forces in the search for efficient renewable energy sources. The conversion of lignocellulosic biomass to energy and useful chemicals is a component of the solution. Ethanol is most commonly produced by enzymatic hydrolysis of complex carbohydrates to simple sugars followed by fermentation using yeast.

C₆H_l0O₅ + H₂O −Enxymes→ C₆H₁₂O₆ −Yeast→ 2CH₃CH₂OH + 2C0₂

In the U.S. corn is the primary starting raw material for commercial ethanol production. …

Preparation And Characterization Of Melt Blown And Electro-Spun Polyurethane Webs, Constance Rebecca Eastman

Masters Theses

Nonwoven fiber webs were formed through the processes of melt blowing and electro-spinning with the use of polyester thermoplastic polyurethane (TPU), aromatic polyether TPU, and aliphatic polycarbonate TPU. Each polyurethane was used to form fiber webs into sheets and onto stainless steel springs. Three types of fiber sheets were made: (1) melt blown, (2) electro-spun, and (3) melt blown coated with electro-spun fibers to form a composite structure. The melt blown sheets consisted of polyether TPU or aliphatic polycarbonate (PC) TPU. The electro-spun sheets were made from a 15wt% polymer solution of polyester TPU or aliphatic PC TPU. There were …

Rheology Of 1- Butyl-3-Methylimidazolium Chloride Cellulose Solutions, Joy Louise Watson

Masters Theses

Cellulose is the most common organic polymer on earth. It is a natural, biodegradable polymer that can be obtained from any number of renewable sources. Wood, a major source of cellulose, contains cellulose, lignin, and hemicelluloses. It can be used to make regenerated cellulosic fibers such as rayon whose manufacturing process involves chemicals which are toxic to humans and the environment. Ionic liquids (ILs) are a class of environmentally benign solvents some of which dissolve cellulose.

Cellulose can be dissolved in 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl), an IL. Solutions of [C₄mim]Cl and cellulose with various concentrations were prepared …

Mathematical Modeling Of High Temperature And High Pressure Dense Membrane For Separation Of Hydrogen From Gasification, Ifeyinwa J. Iwuchukwu

Masters Theses

There is an increasing interest in the use of inorganic membranes as a means of separating gas mixtures at high temperatures and pressures. The most important membrane properties are high permeability and selectivity, and good mechanical, thermal and chemical stability. Dense Pd-based composite membranes are suitable for hydrogen separation and use in catalytic membrane reactors because of their high permeability, good surface properties and high selectivity for hydrogen transport. At UTSI, Pd/AlO23 membranes were prepared by a special method of laser based thermal deposition of the thin film Pd on a ceramic substrate by Nd-YAG laser irradiation of PdCl2 coating …

Modeling And Data Analysis Of Conductive Polymer Composite Sensors, Hua Lei

Theses and Dissertations

Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanism of this type of sensors, a model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8–60 vol.% carbon) were constructed by depositing thin films of a carbon black–polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry …

Investigation Of Ethanol Dehydration In A Microscale Pervaporation Process, Sudhir Ramprasad

Doctoral Dissertations

Challenges due to surface tension effects for vaporization in microchannels have restricted the implementation of conventional separation processes that involve liquid boiling in a micro-chemical system. However, membrane separations offer a feasible alternative for exploring the advantages of liquid phase separation in micro-chemical systems. The main objective of this research was to evaluate the process intensification effects in a microscale pervaporation process with experiments involving the separation of ethanol/water using a commercially available polymer dehydration membrane.

The microchannels in the microseparator were fabricated by the dry etch process at Louisiana Tech University. Microchannel depths of 20 to 120 μm, with …

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 …

Thermodynamic Characterization Of Polymeric Materials Subjected To Non-Isothermal Flows: Experiment, Theory And Simulation, Tudor Constantin Ionescu

Doctoral Dissertations

Frictional or viscous heating phenomena are found in virtually every industrial operation dealing with processing of polymeric materials. This work is aimed at addressing some of the existing shortcomings in modeling non-isothermal polymer flowing processes. Specifically, existing theories suggest that when a polymer melt is subjected to deformation, its internal energy changes very little compared to its conformational entropy. This statement forms the definition of the Theory of Purely Entropic Elasticity (PEE) applied to polymer melts. Under the auspices of this theory, the temperature evolution equation for modeling the polymer melt under an applied deformation is greatly simplified. In this …

A Hamiltonian-Based Algorithm For Equilibrium Molecular Dynamics Simulation At Constant Chemical Potential, Johanna Marie Reyes

Masters Theses

The objective of the research described in this thesis is to determine whether dilating mass can produce an equilibrium molecular dynamics algorithm for rigorous constant chemical potential simulation. The hypothesis is tested by developing an equilibrium molecular dynamics algorithm for the grand ensemble (constant chemical potential, volume and energy ensemble or μVƐ ensemble) following a methodical procedure developed by Keffer et al. [1] and running simulations on possibly a μVƐ ensemble. A novel concept for a chemicostat controller is described. An equation for the instantaneous chemical potential is not available, thus a property, called the instantaneous partial specific Hamiltonian, …

Design Of A Reagentless Enzymatic Amperometric Alcohol Biosensor: Yeast Alcohol Dehydrogenase And Nicotinamide Adenine Dinucleotide On Vertically Aligned Carbon Nanofibers, Martha Lee Weeks

Masters Theses

A reagentless amperometric enzymatic biosensor was constructed on a carbon substrate for the detection of ethanol, methanol, and isopropanol. Yeast alcohol dehydrogenase (YADH), an oxidoreductase enzyme, and its cofactor nicotinamide adenine dinuleotide (NAD⁺) were immobilized by adsorption and covalent attachment to the carbon substrate. Carbon nanofibers grown by plasma enhanced chemical vapor deposition (PECVD) were chosen as the electrode material due to their excellent structural and electrical properties.

Electrochemical techniques were employed to test the function and performance of the constructed biosensor. Characterization of the electrode was performed using NADH. This allowed the function of the electrode to …

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 …

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 …

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 …

The Effect Of Bacterial Chemotaxis On In Situ Bioremediation Rate, Christopher John O'Lenick

Doctoral Dissertations

The process of sensing an attractant chemical by a motile bacterium and subsequent motion towards that attractant, known as chemotaxis, occurs in Escherichia coli, Pseudomonas putida G7, Rhizobium meliloti, and several other subsurface strains. To date, there have been no widely accepted experimental studies that demonstrate whether bacterial chemotaxis can enhance biodegradation of contaminants in the subsurface. This research investigates the effect of bacterial chemotaxis on degradation rate in an experimental model for in situ bioremediation. The novel experimental protocols of this work, developed to investigate bacterial chemotaxis and migration, have provided for the systematic evaluation of the …

Toward Molecular Dynamics Simulation Of Complex Molecular Systems, Chao Li

Masters Theses

Molecular Dynamics (MD) simulation computes atomic trajectories by solving equations of motion numerically using empirical force fields. MD simulation generates information at the microscopic level and uses statistical mechanics to convert this microscopic information to macroscopic observables. Simulation of large molecules, such as chain molecules and biomolecules, however, requires enormous computing work. One way to achieve the simulations is to utilize more powerful computers, such as parallel machines. Another way is to develop efficient algorithms to save the calculations without losing accuracy. This project is to develop a code to perform MD on systems of the mixers, which contain numbers …

Rheology Of Lignin And Lignin/Pet Blends, Jesse Daniel Bush

Masters Theses

Lignin is the second most abundant biomass resource on the planet. It results in industrial quantities as a byproduct of pulping industry and is mostly used as fuel in the pulping chemicals recovery process. Due to the high content of carbon and hydrogen, it can be also used for making carbon fibers. In this thesis some rheological characteristics of the lignin/polyester blends are presented. Polyesters are added to enhance the process ability of the lignin for manufacturing carbon fiber precursors by melt spinning. The effect of polyester addition on viscosity and dynamic moduli of different lignins (organosolv, washed kraft, and …

Graphitized Carbon Foam With Phase Change Material, Angelinda D. Fedden

Theses and Dissertations

This thesis examines the transient heating and cooling responses of graphitized carbon foam infiltrated with phase change material (PCM). The carbon foam provides rapid heat transfer throughout the PCM volume, while the PCM stores the heat for later removal. The foam/PCM system was heated with a copper heating block, and then cooled with a liquid-cooled heat removal block. Infiltrating the foam with PCM significantly increased the length of time before the system reached maximum temperature. The temperature response of the foam/PCM system was consistent over multiple cycles of heating and cooling. A high density foam had a faster heating and …

Cycle Performance Of A Pulse Detonation Engine With Supercritical Fuel Injection, Timothy M. Helfrich

Theses and Dissertations

Pulse detonation engines (PDE) rely on rapid ignition and formation of detonation waves. Because hydrocarbon fuels are composed typically of long carbon chains that must be reduced in the combustion process, it would be beneficial to create such reduction prior to injection of fuel into the engine. This study focused on PDE operation enhancements using dual detonation tube, concentric-counter-flow heat exchangers to elevate the fuel temperature up to supercritical temperatures. Variation of several operating parameters included fuel type (JP-8, JP-7, JP-10, RP-1, JP-900, and S-8), ignition delay, frequency, internal spiral length, and purge fraction. To quantify the performance, four key …

A Plastic-Based Thick-Film Li-Ion Microbattery For Autonomous Microsensors, Qian Lin

Theses and Dissertations

This dissertation describes the development of a high-power, plastic-based, thick-film lithium-ion microbattery for use in a hybrid micropower system for autonomous microsensors. A composite porous electrode structure and a liquid state electrolyte were implemented in the microbatteries to achieve the high power capability and energy density. The use of single-walled carbon nanotubes (SWNTs) was found to significantly reduce the measured resistance of the cathodes that use LiAl0.14Mn1.86O4 as active materials, increase active material accessibility, and improve the cycling and power performance without the need of compression. Optimized uncompressed macro cathodes were capable of delivering power densities greater than 50 mW/cm2, …

Phase Transitions Of Poly (L-Lactic Acid) In Bulk And In Solution, Jing Zhang

Dissertations

Poly(L-lactic acid) (PLLA) has been subject to intensive research in recent years because of its biodegradability. Applications of PLLA, such as porous tissue engineering scaffolds and excipients for controlled release, have been developed in the biomedical and pharmaceutical fields. The crystal structures and morphologies of this semicrystalline polyester are the underlying factors that determine the mechanical and degradation properties of PLLA.

A fundamental understanding of the development of crystal structures and morphologies during the phase transitions of PLLA in bulk and in solution is pursued in this dissertation. Synchrotron wide- and small-angle x-ray scattering (WAXS and SAXS) are adopted as …

Modification Of Clays With Ionic Liquids For Polymer Nanocomponents, Neung Hyun Kim

Theses

In attempts to prepare nanofillers with enhanced compatibility with a polymer matrix, cationic and anionic clays susceptible to exchange of their interlamellar ions with a variety of other cations or anions, were selected.

In order to treat cationic clay, montmorillonite, which contains sodium ions as interlayer ions, reagents having cations differing in size and structure included three ionic liquids ([EMIM]⁺ [Br]^-, [HXMIM]⁺ [Cl]^-, and [Epty]⁺ [BF4]^-). Results indicated that cationic exchange did occur from aqueous solution as confirmed by FTIR, EDX, WAXS, TGA, and elemental analysis. WAXS indicated a significant increase …

Fuel-Nox Formation During Low-Grade Fuel Combustion In A Swirling-Flow Burner, Chunyang Wu

Theses and Dissertations

Insufficient knowledge of fireside behavior in the near-burner region during biomass combustion is one of major factors preventing widespread use of this renewable fuel in pulverized coal power plants. The current research is aimed to investigate the impact of biomass cofiring on NO formation in the near-burner region through interpretation of computational fluid dynamics (CFD) predictions and data collected from a series of biomass tests in a pilot-scale (0.2 MW), swirling flow burner. Two-dimensional gas species mole fraction data were collected with state-of-theart instruments from nine experiments, composing one herbaceous biomass (straw), one woody biomass (sawdust), a low sulfur sub-bituminous …

Kinetic Characterization For Pretreatment Of Timber Varieties And Switchgrass Using Diluted Acid Hydrolysis, Shu Chiang Yat

Dissertations, Master's Theses and Master's Reports - Open

In recent years, growing attention has been devoted to the use of lignocellulosic biomass as a feedstock to produce renewable carbohydrates as a source of energy products, including liquid alternatives to fossil fuels. The benefits of developing woody biomass to ethanol technology are to increase the long-term national energy security, reduce fossil energy consumption, lower greenhouse gas emissions, use renewable rather than depletable resources, and create local jobs. Currently, research is driven by the need to reduce the cost of biomass-ethanol production. One of the preferred methods is to thermochemically pretreat the biomass material and subsequently, enzymatically hydrolyze the pretreated …

Enzyme Engineering Of Aminotransferases For Improved Activity And Thermostability, Abraham Rogelio Mártin García

Dissertations, Master's Theses and Master's Reports - Open

The production by biosynthesis of optically active amino acids and amines satisfies the pharmaceutical industry in its demand for chiral building blocks for the synthesis of various pharmaceuticals. Among several enzymatic methods that allow the synthesis of optically active aminoacids and amines, the use of minotransferase is a promising one due to its broad substrate specificity and no requirement for external cofactor regeneration. The synthesis of chiral compounds by aminotransferases can be done either by asymmetric synthesis starting from keto acids or ketones, and by kinetic resolution starting from racemic aminoacids or amines.

The asymmetric synthesis of substituted (S)-aminotetralin, an …

Development And Modeling Of Thermally Conductive Resins For Fuel Cell Bipolar Plate Applications, Michael G. Miller

Dissertations, Master's Theses and Master's Reports - Open

Thermally conductive resins are a class of material that show promise in many different applications. One growing field for their use is in the area of bipolar plate technology for fuel cell applications. In this work, a LCP was mixed with different types of carbon fillers to determine the effects of the individual carbon fillers on the thermal conductivity of the composite resin. In addition, mathematical modeling was performed on the thermal conductivity data with the goal of developing predictive models for the thermal conductivity of highly filled composite resins.