Engineering Commons^™

Analysis Of Biomass/Coal Co-Gasification For Integrated Gasification Combined Cycle (Igcc) Systems With Carbon Capture, Henry A. Long Iii

University of New Orleans Theses and Dissertations

In recent years, Integrated Gasification Combined Cycle Technology (IGCC) has become more common in clean coal power operations with carbon capture and sequestration (CCS). Great efforts have been spent on investigating ways to improve the efficiency, reduce costs, and further reduce greenhouse gas emissions. This study focuses on investigating two approaches to achieve these goals. First, replace the subcritical Rankine steam cycle with a supercritical steam cycle. Second, add different amounts of biomass as feedstock to reduce emissions. Finally, implement several types of CCS, including sweet- and sour-shift pre-combustion and post-combustion.

Using the software, Thermoflow®, this study shows that utilizing …

Chemical Templating By Afm Tip-Directed Nano-Electrochemical Patterning, Kyle A. Nelson

Theses and Dissertations

This work has examines the creation and use of chemical templates for nanocircuit and other nanodevice fabrication. Chemical templating can be useful in attachment, orientation and wiring of molecularly templated circuits. DNA origami provides a suitable method for creating molecularly templated circuits as DNA can be folded into complex shapes and functionalized with active circuit elements, such as semiconducting nanomaterials. Surface attachment of DNA origami structures can be accomplished by hybridization of dangling single-stranded DNA (ssDNA) on the origami structures with complementary surface-bound strands. Chemical templating provides a pathway for placing the patterned surface-bound attachment points needed for surface alignment …

Effects Of Internals Configurations On Heat Transfer And Hydrodynamics In Bubble Columns - With And Without Solid Particles, Anil Kumar Jhawar

Electronic Thesis and Dissertation Repository

Internals of different types are required in a number of industrial applications of bubble columns to achieve the desired mixing or to remove the heat of reaction to maintain desired temperature and isothermal conditions of operation. Some of these applications include Fischer-Tropsch synthesis, methanol synthesis, and production of dimethyl ether (DME). The presence of internals however can alter the column hydrodynamics and mixing patterns which could influence reactor performance. A fast response probe capable of capturing bubble dynamics, as well as detecting flow direction is used to study the effect of internals on local heat transfer and column hydrodynamics in …

Modeling Solid Propellant Ignition Events, Daniel A. Smyth

Theses and Dissertations

This dissertation documents the building of computational propellant/ingredient models toward predicting AP/HTPB/Al cookoff events. Two computer codes were used to complete this work; a steady-state code and a transient ignition code Numerous levels of verification resulted in a robust set of codes to which several propellant/ingredient models were applied. To validate the final cookoff predictions, several levels of validation were completed, including the comparison of model predictions to experimental data for: AP steady-state combustion, fine-AP/HTPB steady-state combustion, AP laser ignition, fine-AP/HTPB laser ignition, AP/HTPB/Al ignition, and AP/HTPB/Al cookoff. A previous AP steady-state model was updated, and then a new AP …

Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar

Doctoral Dissertations

The ionomer-membrane interface in a membrane electrode assembly connects the catalyst and membrane and allows hydrated protons to move between the catalyst and membrane. The continuous operation of the polymer membrane electrolyte fuel cell at high temperature and/or in frequent freeze/thaw cycles leads to membrane degradation and delamination of the interface, which lower the proton conductivity. In this dissertation, we modeled the chemical degradation and proton conductivity of perfluorosulfonic acid (PFSA) ionomers by ab initio calculations and macroscopic modeling. All ab initio calculations were performed using Gaussian 03 suites of program by employing B3LYP/6-311++G** method/basis set. The macroscopic modeling involves …

Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni

All Dissertations

Both petroleum pitches and pitches derived from pure polycyclic aromatic hydrocarbons (PAHs) are oligomeric materials that can serve as precursors for a wide variety of advanced carbon materials. The goal of this study was the structural characterization and quantitative analysis of the dominant constituent oligomers and species present in these pitches.
A key requirement for such work is the ability to fractionate these complex mixtures into samples of narrow molecular weight distribution (mol wt; MWD) that can be used as standards. To this end, semicontinuous (or semibatch) dense-gas/supercritical extraction (DGE/SCE) was used to produce monomer, dimer, and trimer fractions of …

Modeling And Synthesis Of Functionalized Meta-Poly(Phenylene Ethynylene) Helical Structures, Ha Nguyen

All Dissertations

The ability of meta-poly(phenylene ethynylene) (mPPE) materials to undergo random coil to helix conformational changes under select conditions affords many opportunities for their use in sensor, separation, catalysis, and bio-related applications. Thus, to advance the development of these materials, a modeling procedure based on replica exchange molecular dynamics (REMD) simulation was developed to reliably assess factors affecting the folding behaviors of functionalized mPPE variants in solution. A combinational modeling study of 20 functionalized mPPEs in five solvent conditions provided insight into how mPPE secondary structure is impacted by the complex relationship between mPPE functional groups and solvent moieties. Further, these …

Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp

All Dissertations

Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available.
In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M–50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order …

Chlorine Absorption Utilizing Caustic Sodium Sulfite, Henry Mcdonald

All Theses

A scrubber was required to abate a waste stream containing chlorine gas created in the electrolytic dissolution step of the aqueous polishing process at the Mixed Oxides Fuel Fabrication Facility at Savannah River Site, South Carolina. A method of absorption that utilized caustic sodium sulfite as the scrubbing agent was studied for implementation in the process. This method was found to be highly efficient with respect to process requirements, and it was also found to provide enhanced performance over the more conventional method of chlorine scrubbing which uses only aqueous sodium hydroxide as a reagent. Sulfite provides an additional advantage …

Proteome Based Development Of Novel Affinity Tail For Immobilized Metal Affinity Chromatography And Hydrophobic Interaction Chromatography, Neha Tiwari

Graduate Theses and Dissertations

At industrial scale, reducing the step in purification and recovery is desired; this not only decreases the cost but also increases the yield. Hydrophobic Interaction Chromatography (HIC) and Immobilized Metal Affinity Chromatography (IMAC) both are not harsh on biological structure or activity of proteins; also both the techniques are economical and therefore a suitable choice at industrial level. This dissertation comprises of three parts. Purpose for the Part I was to identify and characterize Escherichia coli proteins which display affinity towards both IMAC and Hydrophobic Interaction Chromatography (HIC). Co (II) IMAC was chosen as the primary capture step, followed by …

Degradation Of Polystyrene Foam Under Radiant Heat Flux, James Butler

Graduate Theses and Dissertations

As the demand for liquefied natural gas has increased, safety concerns about the performance of transport vessels under fire conditions have been raised. Current codes for the sizing of the pressure relief systems require that the vessels are able to withstand an emmissive heat flux of 108kW/m2 and do not take into account the effects of insulation loss due to thermal decomposition of the insulation materials. To address this possible oversight in the current code models were presented to a working group organized by the Society of International Gas Tanker and Terminal Operators Ltd. focusing on the decomposition rate of …

Synthesis And Characterization Of Catalysts For The Selective Transformation Of Biomass-Derived Materials, Isaac Tyrone Ghampson

Electronic Theses and Dissertations

The experimental work in this thesis focuses on generating catalysts for two intermediate processes related to the thermal conversion of lignocellulosic biomass: the synthesis and characterization of mesoporous silica supported cobalt catalysts for the Fischer-Tropsch reaction, and an exploration of the reactivity of bulk and supported molybdenum-based nitride catalysts for the hydrodeoxygenation (HDO) of guaiacol, a lignin model compound. The first section of the work details the synthesis of a series of silicasupported cobalt Fischer-Tropsch catalysts with pore diameters ranging from 2-23 nm. Detailed X-ray diffraction measurements were used to determine the composition and particle diameters of the metal fraction, …

Adsorption And Diffusion Of Light Hydrocarbons In Ddr Zeolite, Adam Vidoni

Electronic Theses and Dissertations

This thesis reports the results of an experimental study aimed at characterizing the transport properties of DDR crystals (a pure silica zeolite analog) by the “zero length column” technique. This material is potentially useful as a size selective molecular sieve adsorbent for separation of CH₄ – CO₂ in the upgrading of low grade natural gas (or biogas) as well as for the separation of C₃H₆ - C₃H₈ for production of polypropylene. In both these applications pure silica zeolites (such as DDR) have important practical advantages over the traditional cationic zeolites since they …

Characterization Of Mesoporous Materials Via Fluorescent Spectroscopic Methods, Raymond Russell Kennard

Electronic Theses and Dissertations

There are three components that need to be understood to create new porous membranes for industrial applications. 1.) To understand appropriate synthesis conditions to create a successful membrane system. 2.) To understand how the microstructures generated in synthesis affect the transport properties of that system. 3) To be able to characterize the heterogeneity of the fabricated membrane’s transport and physical structure.

Presented within this manuscript are new characterization methods to increase the understanding in membrane technology. It will be demonstrated that the novel application of standard fluorescent methods and the development of new fluorescent methods techniques allows for the measurement …

Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson

All Dissertations

Polymeric optical materials generally are comprised of amorphous polymers that are transparent in at visible wavelengths but exhibit strong absorption bands in the near-infrared making them less useful for many optical applications. Attenuation, which is the absorption per unit length, largely results from the high vibrational energy associated with carbon-hydrogen bonds contained in the polymer backbone. Attenuation can be mitigated by optical amplification utilizing light emitting additives. Investigated in this dissertation are synthesis techniques for the fabrication of light-emitting polymer nanocomposites and their resultant thermal and rheological characteristics for potential use as polymer optical fibers or films.
Inorganic nanocrystals doped …

Selective Deposition Of Metallic And Semiconductor Materials Onto Dna Templates For Nanofabrication, Jianfei Liu

Theses and Dissertations

This work examines the selective deposition of metallic and semiconductor materials onto DNA templates for the fabrication of nanodevices. DNA origami provides a simple and robust method for folding DNA into a variety of shapes and patterns and makes it possible to create the complex templates needed for nanodevices, such as nanoelectronic circuits, plasmonics, and nanosensors. Metallization of DNA origami templates is essential for the fabrication of such nanodevices. In addition, selective deposition of semiconductor materials onto the DNA template is of importance for making many nanodevices such as nanocircuits. Metallization of DNA origami presents several challenges beyond those associated …

Investigations Of Transesterification Of Canola Oil With Methanol And Ethanol For A New Efficient Method Of Biodiesel Production, Krupal Pal

Electronic Thesis and Dissertation Repository

Transesterification of vegetable oil to biodiesel is a multistep process affected by mass transfer, mixing and chemical reaction equilibrium. Attempts have been made in this study to overcome these limitations by gradually feeding oil into a pool of alcohol. This approach provided large excess of alcohol to allow reaction to proceed further as well as allowed easy dispersion of oil into the alcohol. As a result improved conversion of feed, higher yield and better product quality were achieved. Comparisons have been made with other methods to show the differences and highlight improvements. Reactions were conducted at various reaction conditions for …

Determination Of Isotherms Of Enantiomers On A Chiral Stationary Phase Using Supercritical Fluid Chromatography, Wade Newlin Mack Ii

USF Tampa Graduate Theses and Dissertations

Supercritical fluids provide a robust, tunable environment with favorable transport properties and enhanced solubility. Supercritical carbon dioxide is an environmentally friendly substance that has distinct advantages to traditional solvents used in large scale chemical processing. Ibuprofen is an enantiomeric drug that has been shown to fight prostate cancer and has been used as a mild Alzheimer's disease treatment in the S conformation. Purification of high value products with decreased hazardous material consumption is accomplished by employing supercritical fluid chromatography (SFC). Large scale, single enantiomer purification of pharmaceuticals is dependent on scale-up information. Equilibrium isotherms provide the necessary information to scale-up …

Surface Modification Of Liposomes Containing Nanoemulsions, Jonathan Michael Hartley

Theses and Dissertations

Many attempts have been made to make cancer therapy more selective and less detrimental to the health of the patients. Nanoparticles have emerged as a way to solve some of the problems of traditional chemotherapy. Nanoparticles can provide protection for the therapeutic from degradation or clearance, as well as protection to healthy tissue from the damaging effects of chemotherapy drugs. Researchers are pursuing different strategies but all have the same goals of improving the outcomes of cancer patients. The field of controlled release of drugs has increased significantly in hopes of better treating diseases like cancer. Improved control of drug …

Computational Studies Of Ion Transport In Polymer Electrolytes, Hui Wu

Doctoral Dissertations

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate …

Role Of Ammonia In The Activiation Of Methanol Dehydrogenase/Cytochrome C(L) Enzyme, Ancy Kunjumon

Doctoral Dissertations

Recent advancement in enzyme catalysis has opened ways to design efficient biocatalysts, bio-sensors and bio-fuel cells. An in-depth knowledge about the mechanism of the reaction taking place within the enzymes is of great importance to achieve these goals. In this dissertation, various computation methods are applied to investigate the mechanism behind enzyme catalysis in the presence of compounds called activators.

Methanol dehydrogenase (MDH) is a well-known bio-catalyst that can oxidize excess of methanol from the environment to formaldehyde. The enzyme works well within the bacterial environment, but under in vitro, it loses activity. Ammonia is used as an activator …

Effects Of Pressure On The Properties Of Coal Char Under Gasification Conditions At High Initial Heating Rates, Randy C. Shurtz

Theses and Dissertations

The effects of elevated pressure and high heating rates on coal pyrolysis and gasification were investigated. A high-pressure flat-flame burner (HPFFB) was designed and built to conduct these studies. The HPFFB was designed to provide an environment with laminar, dispersed entrained flow, with particle heating rates of ~10^5 K/s, pressures of up to 15 atm, and gas temperatures of up to 2000 K. Residence times were varied from 30 to 700 ms in this study. Pyrolysis experiments were conducted at particle heating rates of ~10^5 K/s and maximum gas temperatures of ~1700 K at pressures of 1 to 15 atm. …

Phospholipid Transport In Silicon Hydrogel Contact Lenses, Yibei Zhao

Theses and Dissertations

Dry eye syndrome has been associated with the lack of phospholipids in the tear film, leading to disruption of the tear film and subsequent irritation. Characterization of the transport and release of phospholipids from a silicone hydrogel contact lens is required to assess the possible use of these lenses for phospholipid delivery to increase patient comfort. This thesis examines the use of silicone hydrogel contact lenses as phospholipid delivery devices. Contact lenses of silicone hydrogel composition were loaded with varying amounts of radiolabeled 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) from a solution of n-propanol. These lenses were eluted at 35°C into artificial …

Evaluation Of Cathode Materials For Low Temperature (500-700c) Solid Oxide Fuel Cells, Alexander M. Lassman

Master's Theses

Solid oxide fuel cells (SOFC) have gained a great deal of interest, due to their potential for high efficiency power generation and ability to utilize hydrogen fuel, as well as various hydrocarbon-based fuels. A recent trend in SOFC development has been towards lower operating temperatures (500-700°C), which can substantially reduce the cost and complexity of the system. This thesis presents an investigation into state of the art Ba- and La- based cathode materials for use in low temperature (500-700°C) solid oxide fuel cells.

Synthesis of A-site deficient [A=0.97] Ba_0.5Sr_0.5Co_0.8Fe_0.2O₃ (BSCF) was …

Role Of Strongly Interacting Additives In Tuning The Structure And Properties Of Polymer Systems, Vikram Kumar Daga

Open Access Dissertations

Block copolymer (BCP) nanocomposites are an important class of hybrid materials in which the BCP guides the spatial location and the periodic assembly of the additives. High loadings of well-dispersed nanofillers are generally important for many applications including mechanical reinforcing of polymers. In particular the composites shown in this work might find use as etch masks in nanolithography, or for enabling various phase selective reactions for new materials development. This work explores the use of hydrogen bonding interactions between various additives (such as homopolymers and non-polymeric additives) and small, disordered BCPs to cause the formation of well-ordered morphologies with small …

Modeling And Simulation Of Nanoparticle Formation In Microemulsion Droplets, Sreekumar R. Kuriyedath

Open Access Dissertations

Semiconductor nanocrystals, also known as quantum dots (QDs), are an important class of materials that are being extensively studied for a wide variety of potential applications, such as medical diagnostics, photovoltaics, and solid-state lighting. The optical and electronic properties of these nanocrystals are different from their bulk properties and depend on the size of the QDs. Therefore an important requirement in their synthesis is a proper control on the final nanoparticle size. Recently, a technique has been developed for synthesizing zinc selenide (ZnSe) QDs using microemulsion droplets as templates. In these systems, a fixed amount of a reactant is dissolved …

Separation Of Carboxylic Acids From Aqueous Fraction Of Fast Pyrolysis Bio-Oils Using Nanofiltration And Reverse Osmosis Membranes, Achyuta Vara Prasada Rao Teella

Open Access Dissertations

There has been a growing interest in renewable sources of energy due to an increase in demand and potential shortages and environmental problems associated with fossil fuels. Bio-oils, complex liquid fuels produced from fast pyrolysis of biomass, have been recognized as one potential source of renewable energy. However, they cannot be utilized directly due to their high viscosity, corrosiveness, and high char content. Bio-oils readily phase separate into aqueous phase and organic phase upon addition of water. The aqueous fraction of bio oil (AFBO) is convenient to process and contains sugars, organic acids, hydroxyacetone, hydroxyacetaldehyde, furfural, phenols and other organic …

Development Of Plant Cell Culture Processes To Produce Natural Product Pharmaceuticals: Characterization, Analysis, And Modeling Of Plant Cell Aggregation, Martin Kolewe

Open Access Dissertations

Plant derived natural products represent some of the most effective anti-cancer and anti-infectious disease pharmaceuticals available today. However, uncertainty regarding the feasibility of commercial supply due to the limited availability of many plants in nature has resulted in a dramatic reduction in the use of natural products as leads in modern drug discovery. Plant cell suspension culture, consisting of dedifferentiated plant cells grown in vitro and amenable to large scale industrial biotechnology processes, is a production alternative which promises renewable and economical supply of these important drugs. The widespread application of this technology is limited by low product yields, slow …

Theoretical Prediction Of Drug Release In Gi Tract From Spherical Matrix Systems, Naga Lakshmi Ramana Susarla

Dissertations

The significance of controlled release drug delivery systems (CRDDS) lies in their ability to deliver the drug at a steady rate thus reducing the dosage interval and providing a prolonged pharmacodynamic effect. But despite the steadily increasing practical importance of these devices, little is known regarding their underlying drug release mechanisms. Mathematical modeling of these drug delivery systems could help us understand the underlying mass transport mechanisms involved in the control of drug release. Mathematical modeling also plays an important role in providing us with valuable information such as the amount of drug released during a certain period of time …

Effects Of Operating And Geometric Variables On Hydrodynamics And Tablet Dissolution In Standard And Modified Dissolution Testing Apparatuses 2, Yimin Wang

Dissertations

Dissolution testing is routinely conducted in the pharmaceutical industry to provide critical in vitro drug release information for quality control purposes, and especially to assess batch-to-batch consistency of solid oral dosage forms such as tablets. Among the different types of apparatuses listed in the United States Pharmacopoeia (USP), the most commonly used dissolution system for solid dosage forms is the USP Dissolution Testing Apparatus 2, consisting of an unbaffled, hemispherical-bottomed vessel equipped with a 2-blade radial impeller.

Despite its extensive use in industry and a large body of work, some key aspects of the hydrodynamics of Apparatus 2 have received …