Chemical Engineering Commons^™

Simulation Of A Circulating Fluidised Bed Biomass Gasifier Using Aspen Plus: A Performance Analysis, Wayne Doherty, Anthony Reynolds, David Kennedy

Conference Papers

In the near future biomass gasification is likely to play an important role in energy production and conversion. Its application has great potential in the context of climate change mitigation, increasing efficiency and energy security. Atmospheric circulating fluidised bed (CFB) technology was selected for the current study. An original computer simulation model of a CFB biomass gasifier was developed using ASPEN Plus (Advanced System for Process ENgineering Plus). It is based on Gibbs free energy minimisation and the restricted equilibrium method was used to calibrate it against experimental data. This was achieved by specifying the temperature approach for the gasification …

Thermodynamically Coupled Transport In Simple Catalytic Reactions, Yaşar Demirel

Yaşar Demirel Publications

Considerable work published on chemical reaction-diffusion systems investigates mainly mathematically coupled nonlinear differential equations. This study presents the modeling of a simple elementary chemical reaction with thermodynamically and mathematically coupled heat and mass transport with external mass and heat transfer resistances. The thermodynamic coupling refers that a flow occurs without or against its primary thermodynamic driving force, which may be a gradient of temperature or chemical potential. The modeling is based on the linear nonequilibrium thermodynamics approach and phenomenological equations by assuming that the system is in the vicinity of global equilibrium. This approach does not need detailed coupling mechanisms. …

High Performance Zno Varistors Prepared From Nanocrystalline Precursors For Miniaturised Electronic Devices, Suresh Pillai, Declan Mccormack, John Kelly, Raghavendra Ramesh

Articles

An industrially viable solution-based processing route using minimal amounts of solvent has been used to prepare bulk quantity nanopowders (average particle size 15.3 nm) for the fabrication of ZnO varistors. The xerogels, calcined powders and sintered materials were fully characterised. The preparation of varistors from nanopowders has been optimised by studying the effect of temperature on grain growth, densification and breakdown voltage. The varistors are prepared by sintering at 1050 C for 2 hours, a temperature that is significantly lower than that used in the current industrial process. Highly dense varistor discs prepared from the sintered material produce devices, with …

Electrical, Structural, And Chemical Properties Of Semiconducting Metal Oxide Nanofiber Yarns, A. F. Lotus, E. T. Bender, E. A. Evans, R. D. Ramsier, Darrell Hyson Reneker

College of Polymer Science and Polymer Engineering

The electrical, structural, and chemical properties of twisted yarns of metal-oxide nanofibers, fabricated using a modified electrospinning technique, are investigated in this report. In particular, synthesized zinc oxide and nickel oxide yarns having diameters in the range of 4-40 mu m and lengths up to 10 cm were characterized, whose constituent nanofibers had average diameters of 60-100 nm. These yarns have one macroscopic dimension for handling while retaining some of the properties of nanofibers. (C) 2008 American Institute of Physics.

Effect Of Carbon Nanofiber-Matrix Adhesion On Polymeric Nanocomposite Properties—Part Ii, Khalid Lafdi, William Fox, Matthew Matzek, Emel Yildiz

Chemical and Materials Engineering Faculty Publications

A successful integration of two independent phases with good adhesion is imperative for effective translation of superior carbon nanofiber filler properties into a physically superior carbon nanocomposite. Carbon nanofibers were subjected to electrochemical oxidation in 0.1 M nitric acid for varying times.

The strength of adhesion between the nanofiber and an epoxy matrix was characterized by flexural strength and modulus. The surface functional groups formed and their concentration of nanofibers showed a dependence on the degree of oxidation. The addition of chemical functional groups on the nanofiber surface allows them to physically and chemically adhere to the continuous resin matrix. …

Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya

Faculty Publications

A high-throughput high-sensitivity optical technique for measuringmagnetostriction of thin-film composition-spread samples has been developed. It determines the magnetostriction by measuring the induced deflection of micromachined cantilever unimorph samples. Magnetostrictionmeasurements have been performed on as-deposited Fe–Ga and Fe–Ga–Al thin-film composition spreads. The thin-film Fe–Ga spreads display a similar compositional variation of magnetostriction as bulk. A previously undiscovered peak in magnetostriction at low Ga content was also observed and attributed to a maximum in the magnetocrystalline anisotropy. Magnetostrictive mapping of the Fe–Ga–Al ternary system reveals the possibility of substituting up to 8at.%Al in Fe₇₀Ga₃₀ without significant degradation of magnetostriction.

High-Throughput Screening Of Shape Memory Alloy Thin-Film Spreads Using Nanoindentation, Arpit Dwivedi, Thomas J. Wyrobek, Oden L. Warren, Jason R. Hattrick-Simpers, Olubenga O. Famodu, Ichiro Takeuchi

Faculty Publications

We have demonstrated the utility of nanoindentation as a rapid characterization tool for mapping shape memoryalloy compositions in combinatorial thin-film libraries. Nanoindentation was performed on Ni–Mn–Al ternary composition spreads. The indentation hardness and the reduced elastic modulus were mapped across a large fraction of the ternary phase diagram. The large shape memoryalloy composition region, located around the Heusler composition (Ni₂MnAl), was found to display significant departure in these mechanical properties from the rest of the composition spread. In particular, the modulus and the hardness values are lower for the martensite region than those of the rest of the …

Hydrogen Peroxide Formation Rates In A Pemfc Anode And Cathode: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Sathya Motupally, Lesia V. Protsailo

Faculty Publications

Hydrogen peroxide (H₂O₂) formation rates in a proton exchange membrane fuel cell (PEMFC) anode and cathode were estimated as a function of humidity and temperature by studying the oxygen reduction reaction (ORR) on a rotating ring disk electrode. Fuel cell conditions were replicated by depositing a film of Pt/Vulcan XC-72 catalyst onto the disk and by varying the temperature, dissolved O₂ concentration, and the acidity levels in hydrochloric acid (HClO₄). The HClO₄ acidity was correlated to ionomer water activity and hence fuel cell humidity. The H₂O₂ formation rates showed …

Structure Property Relationships In Electron Donating Systems For Potential Photovoltaic Applications., Jonathan Moghal

Doctoral

Conjugated polymers are considered to be one-dimensional semiconductors. In conjugated polymers single and double bonds alternatively bond the carbon atoms along the polymer chain. The loosely bound electrons determine the electronic properties of conjugated polymers. In order to utilise the properties of conjugated polymers in terms of a photovoltaic (PV) device application an acceptor material must be added. The acceptor material used in this study is used in buckminsterfullerence (C60). C60 was selected for this purpose due to its size and the fact that it can accept up to six additional electrons. Ultrafast charge transfers from a conducting polymer onto …

Emulsification And Dispersant Properties Of Sugar Ester Glycolipid In Water In Oil And Oil In Water Emulsion., Azrah Abdul Aziz

Student Works (2010-2019)

The influence of different dispersing agent on the rheological behaviors of paraffin oil-water emulsion with addition of TiO2 for uv-protect and moisturizing active ingredient was studied. While making creams with minimal structural defects and longer storage stability, it is important that preparation conditions be optimized. Settle volume properties, Zeta potential, effective diameter and settle volume of TiO2 suspension were studied in the presence of glycolipid (DDM and Carrageenan), nonionic (PEG 10,000 and Brij 35P) as well as anionic surfactants (sodium dodecyl sulfate, SDS). In the experiments, the higher concentration of dispersing agents shows higher settle volume percentage, higher zeta potential …

Sulphur Removal Using Regenerable Sorbents Of Rare Earth/Transition Metal Oxides, Vikram Reddy Kalakota

LSU Master's Theses

Hot gas desulfurization of gases from primary gasifier can be accomplished using sorbents composed Zn, calcium and transition metal oxide sorbents. The problem with metal oxide sorbents alone is that they are easily reduced at high temperature above 873 K to metallic state under reducing atmosphere decreasing their desulfurization capacity. Sorbents studied for hot gas desulfurization were based on Ce/La/M (M = transition metal) oxides and Ce/La/RE (RE = a rare earth) oxide. Sorbents were prepared using sol-gel method and the rare earth oxides were doped with transition metals using incipient wetness impregnation. Sulfidation experiments were carried out at 873 …

Experimental Study Of A Foam Flow In Horizontal Pipes: Two Flow Regimes And Its Implications, Miodrag Bogdanovic

LSU Master's Theses

Although foam has been widely used in many scientific and engineering applications, the current understanding of foam rheology in pipes is still very limited because of its complex nature. This experimental study, for the first time, investigates the flow rheology of foams in pipes by placing a special emphasis on two distinct foam flow regimes. A wide range of experimental conditions are examined in this study, which include five different surfactant formulations (Cedepal FA-406, Petrostep CG-50, Stepanform 1050, Aquet TD-600, and Ultra-Palmolive), three different surfactant concentrations (0.1, 1, and 5 wt %), two different pipe diameters (0.5 and 1 inch …

Model-Based Framework For Alloy Electrodeposition Processes, Miguel Eduardo Estrada

LSU Master's Theses

The electrodeposition of iron-group alloys has been widely studied due to their interest as materials used for their magnetic and thermo-physical properties. Models such as ternary NiCoFe and quaternary NiCoFeCu multilayer alloys have been previously developed to simulate mass transfer and reaction kinetics. The reactions involved in the models contain kinetic parameters such as rate constants and inverse Tafel slopes which are estimated using trial and error techniques. The previous models are limited to a set of kinetic parameters for each change in concentrations of the electrolyte. Although deposition behaviors such as anomalous codeposition are captured, functionalities to use the …

Evaluation Of Sweep Efficiency Of A Mature Co2 Flood In Little Creek Field, Mississippi, Didem Senocak

LSU Master's Theses

CO2 displacement is the most widely used EOR process, but poor sweep efficiency and large CO2 utilization rates are limitations to the economic and technical success of CO2 floods. Developing a methodology to maximize the sweep efficiency and minimize the CO2 utilization rate would greatly improve the economics of these fields. This thesis evaluates the sweep efficiency of a successful, late-in-life, continuous injection CO2 flood at the Little Creek Field, Mississippi. In this work, we evaluate several heterogeneity measures in terms of recovery efficiency and utilization rate. Core studies available from 41% of the wells in the field were used …

Photocatalytic Oxidation Of Ethanol Using Macroporous Titania, Gibert Merle Magpantay

LSU Master's Theses

Photocatalytic oxidation (PCO) using TiO2 is a potential means of remediating poor indoor air quality that is attributed to low levels of volatile organic compounds (VOC). In this work, ethanol is chosen as a simple compound representative of VOC’s. The aim of this research is to establish a baseline for the photocatalytic activity of TiO2 in ethanol PCO as well as the photonic efficiency of the photoreactor. The PCO conversion could then be enhanced by using photocatalyst having a macroporous structure. A flat plate photoreactor, UV light delivery and a flow system was designed in this work to accomplish ethanol …

Fog-Smog Reactor And Photooxidation Of Naphthalene Within The Fog Condensate In A Uv Light Setup, Neha Shrikant Damle

LSU Master's Theses

Polycyclic aromatic hydrocarbons (PAHs) form a major class of air pollutants. Naphthalene is a commonly found PAH in the atmosphere. Atmospheric fog water contains naphthalene absorbed from surrounding air. The partition coefficient of naphthalene is defined as the ratio of total naphthalene concentration in fog water to total naphthalene concentration in air. The purpose of this research was to determine the partition coefficients of naphthalene for varying reactor temperature. Fog was artificially formed in a predesigned reactor. NaCl aerosols were used as condensation nuclei for fog formation. Fog droplets were exposed to naphthalene vapors in the reactor. The reactor provided …

Groundwater Circulation Well Operation Using Wind Turbine–Generated Energy, Ron Gallagher, Andrew Curtis Elmore

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

An investigation was conducted regarding the potential economic benefits associated with using a wind turbine to power a groundwater circulation well (GCW) at the former Nebraska Ordnance Plant Superfund site. the first phase of the investigation used a 10-kilowatt-rated grid inter-tie wind turbine to partially offset the purchase of electricity from the utility company. the second phase consisted of the conversion of the grid inter-tie system to an off-grid system that stored energy using batteries. during the second phase, the GCW system was operated using either wind turbine power or utility power, and the other system components were operated using …

A Comparison Of Alternating Minimization And Expectation Maximization Algorithms For Single Source Gamma Ray Tomography, R. Varma, S. Bhusarapu, J. A. O'Sullivan, M. (Muthanna) H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Lange and Carson (1984 J. Comput. Assist. Tomogr. 8 306-16) Defined Image Reconstruction for Transmission Tomography as a Maximum Likelihood Estimation Problem and Derived an Expectation Maximization (EM) Algorithm to Obtain the Maximum Likelihood Image Estimate. However, in the Maximization Step or M-Step of the EM Algorithm, an Approximation is Made in the Solution Which Can Affect the Image Quality, particularly in the Case of Domains with High Attenuating Material. O'Sullivan and Benac (2007 IEEE Trans. Med. Imaging 26 283-97) Reformulated the Maximum Likelihood Problem as a Double Minimization of an I-Divergence to Obtain a Family of Image Reconstruction Algorithms, …

Effect Of Hydrodynamic Multiplicity On Trickle Bed Reactor Performance, Werner Van Der Merwe, Willie Nicol, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Multiple Hydrodynamic States in Trickle Bed Reactors Have Been the Subject of Numerous Hydrodynamic Investigations. the Extent of Variation in the Hydrodynamic Parameters (Like Holdup and Pressure Drop) is Large and This Variation Can Be Expected to Have a Significant Impact on the Conversion in a Reaction System. This Study Presents Reaction Data for Α-Methyl Styrene Hydrogenation in a Trickle Bed Reactor over a Range of Conditions that Include Gas and Liquid Limitations. It is Seen that Liquid Flow Rate Variation Induced Hysteresis Has a Large Impact on the Conversion. for Gas-Limited Reactions, the Upper Branch of the Pressure Drop …

Carbon Nanoadditives To Enhance Latent Energy Storage Of Phase Change Materials, Shadab Shaikh, Khalid Lafdi, Kevin P. Hallinan

Chemical and Materials Engineering Faculty Publications

Latent energy storage capacity was analyzed for a system consisting of carbon nanoparticlesdopedphase changematerials (PCMs). Three types of samples were prepared by doping shell wax with single wall carbon nanotubes(SWCNTs), multiwall CNTs, and carbon nanofibers. Differential scanning calorimetry was used to measure the latent heat of fusion. The measured values of latent heat for all the samples showed a good enhancement over the latent heat of pure wax. A maximum enhancement of approximately 13% was observed for the wax/SWCNT composite corresponding to 1% loading of SWCNT. The change in latent heat was modeled by using an approximation for the intermolecular …

Nitrogen And Hydrogen Plasma Treatments Of Multiwalled Carbon Nanotubes, John G. Jones, A. R. Waite, Christopher Muratore, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

This article investigates plasma treatment of vertically aligned multiwall carbon nanotube (CNT) films in different plasma environments for modification of surface chemistry and morphology. The surfaces of the CNTs were functionalized with a pulsed dc plasma treatment, where the power was directly applied to the nanotube film in low pressure argon/nitrogen and argon/hydrogen backgrounds. Optical emission spectroscopy was used to detect atomic and molecular excitations in the gas mixtures as well as in pure gases in the vicinity of the CNT films. In situx-ray photoelectron spectroscopy was performed on the treated samples to examine CNT surface chemistry after treatment. …

Durability Of Perfluorosulfonic Acid And Hydrocarbon Membranes: Effect Of Humidity And Temperature, Vijay A. Sethuraman, John W. Weidner, Andrew T. Haug, Lesia V. Protsailo

Faculty Publications

The effect of humidity on the chemical stability of two types of membranes [i.e., perfluorosulfonic acid type (PFSA, Nafion 112) and biphenyl sulfone hydrocarbon type, (BPSH-35)] was studied by subjecting the membrane electrode assemblies (MEAs) to open-circuit voltage (OCV) decay and potential cycling tests at elevated temperatures and low inlet-gas relative humidities. The BPSH-35 membranes showed poor chemical stability in ex situ Fenton tests compared to that of Nafion membranes. However, under fuel cell conditions, BPSH-35 MEAs outperformed Nafion 112 MEAs in both the OCV decay and potential cycling tests. For both membranes, (i) at a given temperature, …

Enhanced Dielectric Properties In Single Crystal-Like Bifeo3 Thin Films Grown By Flux-Mediated Epitaxy, S.-H. Lim, M. Murakami, J. H. Yang, S.-Y. Young, Jason R. Hattrick-Simpers, M. Wuttig, L. G. Salamanca-Riba, I. Takeuchi

Faculty Publications

We have fabricated single crystal-like BiFeO₃ (BFO) thin films by flux-mediated epitaxy using pulsed laser deposition(PLD). The Bi–Cu–O flux composition and its thickness were optimized using composition spread, thickness gradient, and temperature gradient libraries. The optimized BFO thin films grown with this technique showed larger grain size of ∼2μm and higher dielectric constant in the range of 260–340 than those for standard PLD grown films. In addition, the leakage current density of the films was reduced by two orders of magnitude compared to that of standard PLD grown films.

The Role Of Filler-Matrix Interaction On Viscoelastic Response Of Biomimetic Nanocomposite Hydrogels, Alireza S. Sarvestani, Xuezhong He, Esmaiel Jabbari

Faculty Publications

The effect of a glutamic acid (negatively charged) peptide (Glu6), which mimics the terminal region of the osteonectin glycoprotein of bone on the shear modulus of a synthetic hydorgel/apatite nanocomposite, was investigated. One end of the synthesized peptide was functionalized with an acrylate group (Ac-Glu6) to covalently attach the peptide to the hydrogel phase of the composite matrix. The addition of Ac-Glu6 to hydroxyapatite (HA) nanoparticles (50 nm in size) resulted in significant reinforcement of the shear modulus of the nanocomposite (~100% increase in elastic shear modulus). The reinforcement effect of the Glu6 peptide, a sequence in the terminal region …

Parameter Estimation And Life Modeling Of Lithium-Ion Cells, Shriram Santhanagopalan, Qi Zhang, Karthikeyan Kumaresan, Ralph E. White

Faculty Publications

Lithium-ion pouch cells were cycled at five different temperatures (5, 15, 25, 35, and 45°C ), and rate capability studies were performed after every hundred cycles. The data were used with a simple physics-based model to estimate parameters that capture the capacity fade in the cell, with cycling. The weight of active material within each electrode was estimated as a function of time, using rate capability data at the C/33 rate. The C-rate for these cells is 1.656 A. The capacity fade due to the loss of active material and that due to the loss of cyclable lithium …

Thermal Model For A Li-Ion Cell, Karthikeyan Kumaresan, Godfrey Sikha, Ralph E. White

Faculty Publications

A thermal model for a lithium-ion cell is presented and used to predict discharge performance at different operating temperatures. The results from the simulations are compared to experimental data obtained from lithium-ion pouch cells. The model includes a set of parameters (and their concentration and temperature dependencies) that has been obtained for a lithium-ion cell composed of a mesocarbon microbead anode, LiCoO₂ cathode in 1 M LiPF₆ salt, in a mixture of ethylene carbonate, propylene carbonate, ethyl-methyl carbonate, and diethyl carbonate electrolyte. The parameter set was obtained by comparing the model predictions to the experimental discharge profiles obtained …

Analytical Expression For The Impedance Response For A Lithium-Ion Cell, Godfrey Sikha, Ralph E. White

Faculty Publications

An analytical expression to predict the impedance response of a dual insertion electrode cell (insertion electrodes separated by an ionically conducting membrane) is presented. The expression accounts for the reaction kinetics and double-layer adsorption processes at the electrode-electrolyte interface, transport of electroactive species in the electrolyte phase, and insertion of species in the solid phase of the insertion electrodes. The accuracy of the analytical expression is validated by comparing the impedance response predicted by the expression to the corresponding numerical solution. The analytical expression is used to predict the impedance response of a lithium-ion cell consisting of a porous LiCoO …

A Mathematical Model For A Lithium–Sulfur Cell, Karthikeyan Kumaresan, Yuriy Mikhaylik, Ralph E. White

Faculty Publications

A mathematical model is presented for a complete lithium–sulfur cell. The model includes various electrochemical and chemical (precipitation) reactions, multicomponent transport phenomena in the electrolyte, and the charge transfer within and between solid and liquid phases. A change in the porosity of the porous cathode and separator due to precipitation reactions is also included in the model. The model is used to explain the physical reasons for the two-stage discharge profiles that are typically obtained for lithium–sulfur cells.

Release And Removal Of Microcystins From Microcystis During Disinfection Treatments, Jie Ding

Masters Theses

"The presence of algal toxins, or cyanotoxins, in surface water has been increasingly reported. These highly hazardous toxins are potential threat to both human health and animals by contaminating drinking water sources over the world. In this research project, inactivation of Microcystis aeruginosa cells and release and removal of intracellular microcystins during several oxidative and physical treatments was studied. The results of this study show that chlorine dioxide, sonication, low salinity and quick blending with tissuemiser caused immediate release of microcystin-LR to water after treatment. No significant increase of toxin level was observed after treatment with free chlorine, ozone, permanganate, …

A Coarse-Grain Molecular Dynamics Study Of The Nanotribological Properties Of Nanoparticle Solutions, Ramesh Chembeti

Masters Theses

"In this study, solutions of alkanethiol-capped nanoparticles in alkane are examined using molecular dynamics simulations for their nanotribological potential based on the hypothesis that fluid molecules of very different sizes may interrupt each other's layering tendency to result in less layered or non-layered configurations and provide better lubrication for nanodevices. An effective nanoparticle-nanoparticle pair potential based on previous atomistic approach is used and the temperature and parallel pressure are controlled in place of chemical potential for defining thermodynamic state. When compressed, the confined nanoparticle-containing alkane films generate reduced oscillations in perpendicular forces and smoother expansion in lateral dimensions, indicating lesser …