Chemical Engineering Commons^™

Dielectric Characterization Of Mylar And The Effects Of Doping Processes, Cami B. Belcher

Chemical and Biological Engineering ETDs

Mylar® polymer is a bi-axially oriented polyethylene terephthalate (PET) polymer film used widely as a dielectric, specifically in capacitors. The dielectric characteristics of Mylar have been well studied and documented over the years; however, many of the mechanisms responsible for dielectric breakdown and failure are not understood for modified versions of the material. Previous studies on Mylar confirm that factors such as temperature, humidity, and voltage ramp rates can also have a significant effect on the dielectric properties and measurement of the dielectric properties. This study seeks to determine how dielectric properties, including permittivity, dielectric loss, and breakdown strength, are …

Microbial Biofilm Development And Electron Transfer In Electrochemical Systems, Jose Cornejo

Chemical and Biological Engineering ETDs

Energy harvesting from microorganisms has created vibrant research efforts for the past 20 years that has lead to the development of emerging topics such as microbial electrochemistry, biofilm formation in electrochemical systems and alternative energy technologies applied in environmental processes. In this study we present procedures that aim for further understanding of bacterial physiological conditions in electrochemical systems and interactions between biofilms and solid surfaces, particularly, for the facultative anaerobe Shewanella oneidensis MR-1. These systems consist of microbial fuel cells (MFCs) whose anode component will be evaluated with regards to performance, electrical current generation, and microbial coverage and biofilm development. …

The Electroreduction Of Carbon Dioxide On Porous Copper Nanoparticles, Monica Alisa Padilla

Chemical and Biological Engineering ETDs

Copper nanoparticles of porous, controlled structure were synthesized using the sacrificial support method (SSM). The precursor weight percent (wt%) of copper (Cu) and fumed silica (EH-5) was varied to determine the optimum ratio for this material. The precursors were reduced at i) 350°C in a 7% H2 atmosphere and ii) at 250°C in a 100% H2 atmosphere. The specific surface areas of the nanoparticles was measured by Brunauer-Emmett-Teller N2 absorption. The morphologies and widths of the nanoparticles were confirmed by imaging the nanoparticles by scanning electron microscopy (SEM). The bulk composition of the nanoparticles was determined by X-ray diffraction (XRD). …

Multinode Acoustic Systems For High Throughput Cellular Analysis, Pearlson Prashanth Austin Suthanthiraraj

Chemical and Biological Engineering ETDs

For decades, flow cytometry is used as the gold standard for cellular analyses as it measures multiple properties of single cells. Traditional flow cytometry uses the hydrodynamic focusing technique where the sheath fluid focuses cells in the sample into a narrow stream. Although such precise focusing provides accurate optical measurements, high sheath fluid pressure and high linear velocities limit analysis rate to 50,000 particles/s. Such rates are too low for detecting rare events where one cell may have to be detected in a population of about a billion cells. Therefore, it is necessary to eliminate the sheath fluid and improve …

Impact Of Carbon Support Chemistry, Morphology, And Structure On Platinum Catalyst Durability For Pemfc Applications, Anant Patel

Chemical and Biological Engineering ETDs

Polymer electrolyte membrane fuel cells are a promising alternative energy source, capable of being deployed as successful replacements in many stationary and mobile applications. These devices, however, lack durability, and this has become one of the limiting factors for commercialization. Many projects have focused on finding ways to improve their lifetimes, but few have tried to examine the underlying causes behind their corrosion. The goal of this project was to identify which parameters have a significant impact, both positive and negative, on PEMFC durability. To do this, three series of samples were analyzed using microscopic, spectroscopic, and electrochemical methods. Electron …

Methods Of Cellular Integration And Techniques For Improving Encapsulated Cell Viability For The Purpose Of Developing Living Materials And Cell Based Bio-Sensing Materials, Travis J. Savage

Chemical and Biological Engineering ETDs

Living materials offer the potential for detection-reporter systems based on living cells that are genetically tailored to sense target analytes with high levels of specificity and accuracy. A biotic or living material would allow the development of simple, hand held devices that could be utilized for many applications including industrial process monitoring, environmental remediation, military and defense applications and drug delivery. Many living materials have been developed and characterized but they still lack heightened and prolonged encapsulated cell viability necessary to make the material a candidate for widespread use. One particular material offers several advantages to increase yeast cell viability …

Development Of Novel Bio/Nano Interfaces For Materials Science And Biomedical Applications, Carlee Ashley

Chemical and Biological Engineering ETDs

Virus-like particles (VLPs) of MS2 bacteriophage possess a variety of characteristics that enable their use in biomedical and materials science applications. MS2 VLPs are perfectly monodisperse and possess a highly regular periodic structure. Their protein capsids can be modified in precise locations via chemical conjugation or genetic display of peptides, and their interior volumes can be readily loaded with a variety of non-genomic materials by taking advantage of their ability to self-assemble in the presence of RNA and RNA-modified cargos. Using peptides identified by filamentous phage display, I have demonstrated the utility of MS2 VLPs as targeted nanocarriers capable of …

Reactivity Study Of Platinum Nanoparticles And Nanowires Inside The Channels Of Mesoporous Silica, Marcus R. Smith

Chemical and Biological Engineering ETDs

Pt metal nanowires and nanoparticles were prepared using mesoporous silica as the template. Mesoporous silica with straight 1-dimensional, tortuous 1-dimensional and 3-dimensional channels was used. The experimental techniques included CO oxidation, Chemisorption, XRD, and STEM. CO oxidation and chemisorption provided the data to calculate the intrinsic reactivity, known as turn over frequency (TOF). Powder XRD was used to measure line broadening. The FWHM of the XRD line broadening was used with the Scherrer formula to determine Pt metal crystallite size. STEM images permitted for the measurement of the particle diameters, and the determination of morphology.

Two commercially available reference samples …

Infrared Diode Laser Absorption Spectroscopy Measurement Of Gas Phase Radicals In C₄F Discharges For Plasma Model Validation, Karla Waters

Chemical and Biological Engineering ETDs

The etching characteristics of oxide and photoresist thin films in C₄F₈ discharges in an inductively coupled GEC Reference cell have been determined. Infrared diode laser absorption spectroscopy (IR-DLAS) measured absolute concentrations of CF_x radicals in C₄F₈ discharges and correlated their behavior to the oxide etch process. Additionally, Langmuir probe and OES data were collected to aid in characterizing the plasma and the oxide/photoresist etch processes.

A central composite design of experiment was employed. The factors were source power, chuck bias power, and total pressure. The source power varied from 200 to 500 W, …

Activation Of Precipitated Iron Fischer-Tropsch Catalysts, Mehul D. Shroff

Chemical and Biological Engineering ETDs

The Fischer-Tropsch Synthesis (FTS) is an important step in the manufacture of synthetic fuels from coal. The use of iron catalysts for FTS, though desirable from the standpoint of process economy, is hampered by problems relating to catalyst attrition and carbon buildup. In addition, from a research perspective, there has been a long-standing controversy in the literature with regard to the nature of the active phase.

The effect of activation and reaction treatments on the resulting phase transformations in a commercial, precipitated and spray-dried, Fe₂O₃ - CuO - K₂O Fischer-Tropsch catalyst have been studied. Different …

X-Ray Induced Electron Emission, Charles A. Aeby

Chemical and Biological Engineering ETDs

An experimental technique has been developed and successfully used in the measurement of X-Ray induced electron emission from a variety of materials including a group of significance to satellite applications. A database has been established which extends measure emission characteristics to an order of magnitude lower energies than previously available.

Separations Of Dilute Solutions By The Smooth Deposit Approach Of The In-Situ Indirect Freezing Process, Jeng-Hung Lue

Chemical and Biological Engineering ETDs

The main objective of the present study is to demonstrate experimentally the feasibility of applying the smooth deposit ap­proach of the in-situ indirect freezing process to the separations of both dilute organic mixtures and aqueous mixtures. The in-situ indirect freezing process with in-situ washing and melting opera­tions was first introduced by C. Y. Cheng and S. W. Cheng [1].

Assessment Of Corrosion And Scaling In A Low Temperature Geothermal System, David Bruce Orrell

Chemical and Biological Engineering ETDs

The feasibility of a low temperature geothermal system to be located in the area immediately surrounding Albuquerque, New Mexico, was assessed with respect to corrosion and scaling. Theories of corrosion and scaling were explored and an extensive literature survey was performed to predict trends and apply design criteria and guidelines regarding corrosion and scaling from other geothermal environments to the proposed geothermal installation in Albuquerque. A recirculating corrosion test loop was built, and fifteen metals were tested for general corrosion resistance in seawater at 190° F and 3 ft/sec flow velocity. Results show this test procedure to be viable and …

Deep Penetration Of Electrons Into Homogeneous Media By The Method Of Condensed Collisions, Joseph Francis Janni

Chemical and Biological Engineering ETDs

The objective of this dissertation was to develop an accurate and efficient alternative to presently available methods of calculating the steady state penetration of electrons deep into homogeneous materials. A thorough solution must include scalar fluxes, net currents, angular distributions, and differential energy spectra. This research has successfully developed the method of condensed collisions, which provides an alternative to methods now in use for the solution of the electron transport problem. The condensed collsion method is general, but has been applied specifically to deep penetration electron transport to demonstrate its utility. The present aplication was for electrons having incident energies …

Mass Transfer At The Edge Of A Rotating Disk, Jeffrey Malcolm Cohen

Chemical and Biological Engineering ETDs

A different approach to the problem of mass transfer to a rotating disk, employing less restrictive assumptions, has been undertaken to quantify the phenomenon of mass transfer at the disk's edge. Experimental work in support of theor­etical conjectures was performed as part of this work.

In order to include the effect of mass transfer at the edge on mass transfer to the entire disk, the equation of convective diffusion was solved in two dimensions over a region that extended beyond physical projection of active area of the disk. A synthesis of experimental results and theoret­ical considerations was used to specify …

Concentrated Organic Separations By The Cyclic Indirect Freezing Process, Jeffrey Carl Miles

Chemical and Biological Engineering ETDs

This study demonstrates the technical feasibility of purifying concentrated organic solutions by the cyclic indirect freezing process with in-situ washing and in-situ melting operations. The key to a successful purification in the freezing process is a near plug flow displacement of unfrozen liquor from the bed in an in-situ washing operation. To be successful, a freezing step has to be initiated uniformly and a high permeability bed has to be formed uniformly throughout the freezing conduits. In the study, a nucleation technique based on pressure induced supersaturation has been used to accomplish a uniform initiation and a pressure induced freezing …

Ocean Thermal Energy Conversion By Using A Solidification Melting Cycle, Wen Liang Lin

Chemical and Biological Engineering ETDs

An OTEC (Ocean Thermal Energy Conversion) power plant uses warm surface seawater (24° C - 28° C) as a heat source and deep cold seawater (4° C - 7°C) as a heat sink. With this temperature difference, a heat engine which delivers either mechanical or electric power can be con­structed. There are some limitations and problems of evaporators and condensers to be used in a closed Rankine cycle OTEC plant which have seriously limited the applicability of this concept. This study proposed a process using the S/L engine---a heat engine that utilizes a working medium undergoing solidification and melting operations. …

The Fracture Toughness Of Steel-Aluminum Deformation Welds, Charles Ellis Albright Jr

Chemical and Biological Engineering ETDs

A study of the fracture toughness (in this case, Gic) of steel-aluminum deformation welds using a specially developed double cantilever beam fracture toughness specimen is presented. Welds made at 350C were heat treated at 360, 380, 400, 420 and 440 C.

An intermetallic reaction product layer of Fe2Al5 is formed at the steel-aluminum interface with increasing heat treating temperature and time by a process of nucleation and growth of discrete particles. A transition in toughness from a higher average Gic value (6097 N/m) to a very low average Gic value (525 N/m) is observed. The decrease in toughness is accomplished …

An Investigation Into The Transport Properties And Kinetic Parameters Of Single Coal Particles During Devolatilization, Gregory Forrest Roach

Chemical and Biological Engineering ETDs

This study focuses on the devolatilization step that occurs in the process of coal gasification. This is a key economic step for both the Lurgi synthetic natural gas process and the in-situ gasification that are being proposed for New Mexican coals. The findings of this study may be used by industry to improve the design and operation of these processes.

The work presented is an investigation into the transport properties and kinetic parameters that govern the extent of pyrolysis for single particles of subbituminous coal from the San Juan Basin in north-west New Mexico. The unique feature of this work …

A Simple, Inexpensive Spinning-Drop Interfacial Tensiometer, Humoud S. Al-Rabiah

Chemical and Biological Engineering ETDs

A spinning-drop interfacial tensiometer was designed, built, and tested. The device is very simple, inexpensive to build, and easy to operate compared with other spinningdrop tensiometers.

The tensiometer measures the interfacial tension of liquid-liquid or liquid-vapor systems. Interfacial tensions of three systems were measured to test the device: water-heptane, glycerol-heptane, and glycerol-air.

Experimental results agree with literature values within one percent for the glycerol-heptane system. The variations among the values for the liquid-liquid systems at different rotational speeds are within six percent. Repeated experiments with different drop sizes show that drop size of the glycerol-air system may affect the results. …

Desublimation Of Water Vapor At Low Pressure And Evaporative Freezing Of Seawater, Sun Sea Pao

Chemical and Biological Engineering ETDs

The Vacuum-Freezing Vapor-Desublimation and High Pressure Ice-Melting Process has been developed since 1972. In 1976, Mr. T. C. Chung finished a theoretical study of Low Pressure Water Vapor Desublimation Operation. The writer was a co-worker of Mr. Chung, and had worked with him for the study for four months. The information collected in Mr. Chung's thesis was borrowed and edited as Chapters 1 and 2 in the present thesis. Mr. Chung's theory predicts the rate of water vapor desublimation as a function of the difference between operating temperature and desublimer wall temperature. In the present thesis, experimental rates of desublimation …

A Study Of A Buoyancy Balanced Gas-Liquid Contacting System, Jaw-Ruey Leu

Chemical and Biological Engineering ETDs

In a conventional gas-liquid contacting system that provides a long gas-liquid contact time, a pressurized gas is released at the bottom of a pool of liquid to form gas bubbles; the bubbles move upward through the liquid and break at the surface of the liquid. A large amount of work is spent in pressurizing the gas. Even though it is theoretically possible to recover work from rising bubbles, a work recovery scheme has not been incorporated into a conventional system.

A buoyancy-balanced gas-liquid contacting system concept has recently been introduced. The system comprises two processing zones filled with a liquid, …

Separation Of Organic Solutions By The Indirect Fractional Solidification Process With In-Situ Washing And Melting Operations, Juiuun-Perng Chiang

Chemical and Biological Engineering ETDs

The main objective of the present thesis study is to experimentally investigate the feasibility of purifying both dilute and concentrated organic solutions by the indirect freezing process with in-situ washing and melting operations under industrially practicable operating conditions. The smooth deposit approach and the dendritic deposit approach are respectively used in separating dilute solutions and concentrated solutions and small ΔT's for heat transfer, less than 3 °C, have been used throughout the study.

A convenient ultrasonic device and easily practicable operating procedures for nucleating slightly super-cooled liquids have been developed. Several freezer­melter systems incorporating the new ultrasonic devices have been …

Reactivity And Kinetic Comparison Of Large Single New Mexican And South African Subbituminous Coal Particles, Wendall Gerald Stoddart

Chemical and Biological Engineering ETDs

This study focuses on one aspect of coal gasification; that is, devolatilization of large single coal particles. Devolatilization is an important and key economic step in the overall gasification process. From a commercial standpoint for New Mexico, there are two processes in the field of coal gasification of importance: the Lurgi synthetic natural gas process and in-situ gasification. Since both the Lurgi and in-situ processes treat rather large particles of coal, the findings in this study might be used by industry to improve the design and operation of these processes. The work presented is a study and comparison of the …

Modeling Of A Fossil-Fired Power Plant For Real-Time Simulation, Robert Douglas Busch

Chemical and Biological Engineering ETDs

Computer simulation of complex physical systems can be a useful technique in analyzing the multitude of interactions occurring in such systems. Real-time modeling of power plants is particularly useful in operator training and engineering research programs. Towards this end, a small-scale simulator has been developed using a dedicated minicomputer. Major components of a drum-type fossil-fired power plant were modeled using first principle, physical equations, and then the component modules were interconnected to form the simulation package. Support routines were written to provide real-time operation, periodic data storage, continuous data display, interrupt capabilities, and manipulation of control variables. The package presently …

The Condensation Of Vapor On A Horizontal Rotating Square Tube., Suresh Chandra

Chemical and Biological Engineering ETDs

Heat transfer measurements were made for steam vapor condensing at one atmosphere on the outer surface of a horizontal square tube with a side of one inch, when rotated at between O and 1950 rpm. The Froude number (FR) was based on the side length. Three distinct heat-transfer regimes were observed and are correlated with FR. The first is gravita­tion controlled condensate flow when FR is less than 2.0 and the condensing film heat-transfer coefficient decreases. When 2.0

Kinetics And Dynamics Of Continuous Crystallization, Karichangal C. Parthasarathy

Chemical and Biological Engineering ETDs

A design correlation is presented for the prediction of steady state product size distributions resulting from a continuous crystal­lizer, based upon a single experimental determination. This has been accomplished by the definition of a new parameter called the "degree of crystallization," which has been related to the experimental nuclea­tion and growth rates in a salting-out crystallizer. The correlation resulted from the detection of variations in the suspension density of the mother liquor which has previously been assumed constant in cer­tain power law models. The degree of crystallization has also been described in terms of dimensionless number, length and area moments …

Continuous Crystallization Of High Explosives, Larry E. Hatler

Chemical and Biological Engineering ETDs

Nitroguanidine (NQ) is a high explosive which is commercially available in low bulk density form (0.20 to 0.30 gms/cm³). This low bulk density limits its usefulness as an explosive. High bulk density NQ can be produced from a NQ-N, N-dime-thylformamide-Versamid 125 system when crystallized in a mixed suspension mixed product removal crystallizer. Bulk densities ranged from 0.92 to 1.05 gms/cm³ for the operating conditions used. The effect of agitator speed, growth rate, and solids concentration on nucleation rates was determined using a multiple linear regression technique. The resulting equation is: B₀ = 0.19 (RPM) ^1.54 (G) …

Dispersion In Laminiar Flow Of Non-Newtonian Fluids, Subhash N. Shah

Chemical and Biological Engineering ETDs

In the present investigation, Taylor's analysis of the dispersion of solutes in laminar flow of a Newtonian fluid through a circular tube was extended to the case of a non-Newtonian Eyring model fluid. A new approach was taken to solve the convective diffusion equation for the Eyring model fluid. This approach incorporates the use of the dimensionless longitudinal pressure gradient and the mean velocity to obtain the dimensionless concentration. Using an approach similar to that of Taylor, a solution of the diffusion equation was obtained for quantities such as the dimensionless concentration, mean concentration, and effective dispersion coefficient as a …

An Analysis Of The Behavior Of A Non-Newtonian Fluid In A Flow Reactor, Asahiro Ahagon

Chemical and Biological Engineering ETDs

Velocity, temperature and concentration profiles were derived for non-Newtonian laminar flow of a reacting species in a tubular reactor. The equation of motion based on a temperature dependent power-law fluid model and the energy equation with internal heat generation caused by a first order chemical reaction were coupled and solved simultaneously using numerical methods to yield the profiles. The assumptions made in this study were: constant physical properties of the fluid (density, thermal conductivity and heat capacity). fully developed flow, wall temperature and negligible diffusion. Compartmentalized calculations resulted in velocity, temperature and reactant concentration profiles for both the axial and …