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Jiang, HuaEffect of Changes in Flow Geometry, Rotation and High Heat Flux on Fluid Dynamics, Heat Transfer and Oxidation/Deposition of Jet Fuels
Doctor of Philosophy (Ph.D.), University of Dayton, 2011, Mechanical Engineering

Jet fuel is used in high-performance military flight vehicles for cooling purposes before combustion. It is desirable to investigate the influence of the flow and heating conditions on fuel heat transfer and thermal stability to develop viable mitigation strategies. Computational fluid dynamics (CFD) simulations and experiments can provide the understanding of the fuel physical phenomena which involves the fluid dynamics, heat transfer and chemical reactions. Three distinct topics are studied: The first topic considers the effect of flow geometry on fuel oxidation and deposition. Experiments and CFD modeling were performed for fuels flowing through heated tubes which have either a sudden expansion or contraction. It was found that the peak deposition occurs near the maximum oxidation rate and excess deposition is formed near the step. This study provides information for the fuel system designer which can help minimize surface deposition due to fuel thermal oxidation.

In the second area of study, the fuel passed heated rotational test articles to investigate the effect of rotation on fuel heat transfer. The coupled effects of centrifugal forces and turbulent flow result in fuel temperatures that increase with rotational speed. This indicates that the convective heat transfer is enhanced as rotational speed increases. This work can assist the understanding of using jet fuel to cool the turbine engine.

In the third segment of research, the fuel was exposed to “rocket-like” conditions. This investigation is to explore the effect of high heat flux and high flow velocity on fuel heat transfer and oxidation/deposition. Simulations show a temperature difference over several hundred degrees in the radial direction within the very thin thermal boundary layer under rapid heating. The fuel contacting the interior wall is locally heated to a supercritical state. As a result, the heat transfer is deteriorated in the supercritical boundary layer. Both simulated and measured deposit profiles show a peak deposit near the end of the heated section. These observations may eventually have an application to the design of high speed supersonic vehicles with improved cooling capabilities.

Committee:

Jamie S. Ervin, PhD (Advisor); Steven Zabarnick, PhD (Committee Co-Chair); Timothy J. Edwards, PhD (Committee Member); Kevin P. Hallinan, PhD (Committee Member)

Subjects:

Aerospace Engineering; Mechanical Engineering

Keywords:

jet fuel; heat transfer deterioration; high heat flux; temperature peak; supercritical; fuel properties; nozzle; sudden expansion/contraction in flow path; fuel deposition; turbulence models; rotation passage; recirculation flow; excess deposition

Balagurunathan, JayakishanInvestigation of Ignition Delay Times of Conventional (JP-8) and Synthetic (S-8) Jet Fuels: A Shock Tube Study
Master of Science (M.S.), University of Dayton, 2012, Mechanical Engineering
The global depletion of petroleum-based fuels has led the world to more closely examine alternate fuels. Therefore, alternate fuels produced from feedstocks such as coal, soybeans, palm oil or switch grass through methods such as coal liquefaction, biomass gasification, and Fischer-Tropsch synthesis have been tested. Among these techniques, fuels generated using Fischer-Tropsch technologies are of interest because they produce clean burning hydrocarbons similar to those found in commercial fuels. Therefore, in this study the Fischer-Tropsch derived S-8 fuel was evaluated as a drop-in replacement for the jet fuel JP-8. The jet fuel JP-8 is comprised of n-, iso- and cyclo- alkanes as well as aromatics while the S-8 fuel is primarily comprised of n- and iso- alkanes. The composition of the fuel affects its ignition characteristics chemically and physically by either advancement or delay of time to ignition. Since this study focused on the chemical effects, the fuels were completely pre-vaporized and pre-mixed. A high pressure, high temperature heated single pulse shock tube was used for this study. The shock tube is an established experimental tool used to obtain ignition delay data behind reflected shock waves under operating conditions relevant to modern engines. The experiments were conducted over a temperature range of 1000-1600 K, a pressure of 19±2 atm, equivalence ratios of 0.5, 1 and 3, within a dwell time of 7.6±0.2 ms and an argon dilution of 93% (v/v). Ignition delay times were measured using the signal from the pressure transducer on the end plate with guidance from the optical diagnostic signal. Along with JP-8 and S-8, the ignition delay of n-heptane was also studied. N-heptane was chosen to represent the n-alkanes in the fuels for this study since it was present in both fuels and also to prove the fact that the n-alkanes were rate controlling. The results indicate that both S-8 and JP-8 fuels have similar ignition delays at corresponding equivalence ratios. The fuel-rich mixtures ignited faster at lower temperatures (<1150 K) and the fuel-lean mixtures ignited faster at higher temperatures (>1150 K). In the transition period between lower to higher temperatures (~1100-1200 K), the equivalence ratio had no significant effect on the ignition delay time. The results also show that the ignition delay time measurements of S-8 and JP-8 fuels are similar to the ignition delay of n-heptane at the equivalence ratio of Φ=0.5 and thereby indicate that the n-alkanes present in these fuels controlled the ignition under these conditions. The ignition delay results of S-8 and JP-8 at Φ=3.0 from this study were also compared to prior work (Kahandawala et al., 2008) on 2-methylheptane and n-heptane/toluene (80/20 liquid vol.%), respectively and found to be indistinguishable. This data serves to extend the gas phase ignition delay database for both JP-8 and S-8 and is the first known data taken for both these fuels at higher temperatures (>1000 K) for an equivalence ratio of 3.0 with argon as the diluent gas.

Committee:

Sukh Sidhu, Dr (Committee Chair); Philip Taylor, Dr (Committee Member); Moshan Kahandawala, Dr (Committee Member)

Subjects:

Aerospace Engineering; Aerospace Materials; Alternative Energy; Automotive Engineering; Automotive Materials; Chemical Engineering; Chemistry; Energy; Engineering; Environmental Engineering; Mechanical Engineering; Petroleum Engineering; Technology

Keywords:

Ignition delay; shock tube; S-8; JP-8; Jet fuels; Fuel characteristics; heated shock tube; Fischer-Tropsch; Alternate fuels; alkanes; synthetic fuel; fuel; iso-alkanes; jayakishan balagurunathan

Yee, Shannon K.Nuclear Fuel Cycle Modeling Approaches For Recycling And Transmutation Of Spent Nuclear Fuel
Master of Science, The Ohio State University, 2008, Nuclear Engineering
Policy decisions regarding the direction of nuclear power utilize sophisticated fuel cycle models. Both static and dynamic models are used to determine how a proposed technology will integrate into existing nuclear fuel cycle strategy. Dynamic models in particular are useful because they can better evaluate what-if scenarios. However, some of these models rely on static fuel recipes for loading recycled nuclear fuel. This static approach will lead to considerable uncertainty because it cannot capture the dynamic changes in separated inventory. Thus a better approach for loading recycled fuel is necessary. This thesis presents a better approach to load recycled fuel dynamically in an attempt to best match an available composition to a target composition by employing a novel isotopic reactivity worth value assignment. Once fuel is loaded and consumed in reactors, the resultant spent fuel composition can be determined by utilizing the transmutation approach explained in this thesis. These two approaches allow for modeling of dynamic fuel recycling. This thesis describes these approaches and presents illustrative results that can be incorporated into larger nuclear fuel cycle models.

Committee:

Xiaodong Sun, PhD (Advisor); Vish Subramaniam, PhD (Advisor); Steven Piet, PhD (Committee Member)

Subjects:

Engineering; Mechanical Engineering; Nuclear Chemistry; Nuclear Physics; Physics

Keywords:

fuel cycle; spent nuclear fuel; nuclear fuel recycling; transmutation

Rohaly, Matthew JosephDecomposition of Aromatic Amines in a Jet Fuel Surrogate
Master of Science (M.S.), University of Dayton, 2014, Chemistry
The thermal decomposition of aromatic nitrogen containing compounds in a jet fuel surrogate was studied. The surrogate fuel's decomposition was compared to the decomposition found in natural jet fuels. Then high performance liquid chromatography was used to examine the formation of any polar products from the thermal decomposition of the surrogate fuel. Gas chromatography coupled with mass spectrometry and nuclear magnetic resonance were employed to try and identify the polar products. The large amount of hydrocarbons masking the polar products made fractional collection necessary before any identification could be attempted. After fractional collections were employed several oxygen polar compounds were found and identified from the thermal decomposition of the surrogate fuel. However no nitrogen-containing compounds could be found. This is most likely due to the low concentration of the nitrogen-containing compounds within the surrogate. Due to the effectiveness of the surrogate fuel's thermal decomposition it remains a good candidate for further jet fuel studies that look at reactivity. HPLC was also very effective at observing the formation of polar products within the jet fuel, although it could not identify these products. The fractional collection method that was employed did improve the results of the identification process, but it did not manage enough separation between the polar compounds and the hydrocarbons present in the surrogate. It is likely that a further separation method is needed. GCMS was relatively ineffective at separating and identifying polar products from this reaction. This is due to the bulk hydrocarbons masking the polar product signals. GCMS was able to identify a oxygen-containing compound, but only because the elution point from this compound was far from the elution point of any hydrocarbon. NMR was effective at identifying polar compounds that were present in significant quantities, however the extremely low concentration of the polar products made this process much less effective as well. Overall for GCMS or NMR to be considered effective techniques for this analysis a better separation process must be utilized.

Committee:

David Johnson (Advisor)

Subjects:

Chemistry

Keywords:

jet fuels; jet fuel decomposition; nitrogen contaminants in jet fuels; polar products from jet fuel decomposition; jet fuel separation techniques;

Gardner, PaulAerosol Jet Printing of LSCF-CGO Cathode for Solid Oxide Fuel Cells
Master of Science (MS), Wright State University, 2011, Chemistry
Solid oxide fuel cell (SOFC) technology has attracted great attention due to advantages such as low emissions and high efficiency. In this work, solid oxide fuel cells were fabricated by incorporating functional layers deposited by a novel aerosol jet® printing method. The buffer and cathode layers were printed from gadolinium doped ceria (Ce0.9Gd0.1)O1.95 (CGO) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) inks, respectively. The CGO layer was deposited on the sintered electrolyte and then LSCF was subsequently deposited onto the CGO layer. The polarization curves showed a 19% improvement in current density using LSCF as the cathode instead of LSM. Cathode grain size was shown to change by 85% over the sintering temperatures examined. Lastly, the effect that ethyl cellulose additive had on the resulting cathode was determined. It was discovered that the porosity of the microstructure was not correlated to the additive's molecular weight. The actual causes of the cathode porosity may be the order of polymer branching or the ethoxy content of the ethyl cellulose.

Committee:

Eric Fossum, PhD (Advisor); David Grossie, PhD (Committee Chair); Rachel Aga, PhD (Committee Chair)

Subjects:

Chemistry

Keywords:

solid oxide fuel cell; SOFC; LSCF; cathode; LSM; fuel cell; aerosol jet; aerosol jet deposition; aerosol jet deposition technique; Optomec; AJDT;

Blanchard, Tina-LouiseA Systems Engineering Reference Model for Fuel Cell Power Systems Development
Master of Science in Industrial Engineering, Cleveland State University, 2011, Fenn College of Engineering

This research was done because today the Fuel Cell (FC) Industry is still in its infancy in spite over one-hundred years of development has transpired. Although hundreds of fuel cell developers, globally have been spawned, in the last ten to twenty years, only a very few are left struggling with their New Product Development (NPD). The entrepreneurs of this type of disruptive technology, as a whole, do not have a systems engineering ‘roadmap", or template, which could guide FC technology based power system development efforts to address a more environmentally friendly power generation. Hence their probability of achieving successful commercialization is generally, quite low.

Three major problems plague the fuel cell industry preventing successful commercialization today. Because of the immaturity of FC technology and, the shortage of workers intimately knowledgeable in FC technology, and the lack of FC systems engineering, process developmental knowledge, the necessity for a commercialization process model becomes evident.

This thesis presents a six-phase systems engineering developmental reference model for new product development of a Solid Oxide Fuel Cell (SOFC) Power System. For this work, a stationary SOFC Power System, the subject of this study, was defined and decomposed into a subsystems hierarchy using a Part Centric Top-Down, integrated approach to give those who are familiar with SOFC Technology a chance to learn systems engineering practices. In turn, the examination of the SOFC mock-up could gave those unfamiliar with SOFC Technology a chance to learn the basic, technical fundamentals of fuel cell development and operations. A detailed description of the first two early phases of the systems engineering approach to design and development provides the baseline system engineering process details to create a template reference model for the remaining four phases. The NPD reference template model's systems engineering process, philosophy and design tools are presented in great detail. Lastly, the thesis draws an overall picture of the major commercialization challenges and barriers (both technical and non-technical) that SOFC developers' encounter.

Committee:

L. Kenneth Keys, PhD (Committee Chair); Paul P. Lin, PhD (Committee Member); Walter Kocher, PhD (Committee Member)

Subjects:

Alternative Energy; Business Costs; Business Education; Engineering; Environmental Engineering

Keywords:

Systems Engineering; Systems Development; Reference Model, Solid Oxide Fuel Cells; Fuel Cells; Commercialization

Rottmayer, Michael AProcessing and Properties of Nanocomposite Thin Films for Microfabricated Solid Oxide Fuel Cells
PhD, University of Cincinnati, 2017, Engineering and Applied Science: Materials Science
Microfabricated solid oxide fuel cells (mSOFCs) have recently gained attention as a promising technology, with the potential to offer a low temperature (as low as 300°C), reduced start-up time, and improved energy density for portable power applications. At present, porous Pt is the most common cathode being investigated for mSOFCs. However, there are significant technical challenges for utilizing pure metallic electrodes at the operating temperatures of interest due to their tendency towards Ostwald ripening, as well as no bulk ionic conductivity. Nanocomposite materials (e.g. Pt/YSZ) are a promising alternative approach for providing both microstructural and electrochemical stability to the electrode layer. The overall objective of this research was to explore the processing of nanocomposite metal / metal oxide materials (i.e. Pt/YSZ) for use as a high performance cathode electrode for mSOFCs. The Pt/YSZ nanocomposite cathodes were deposited through a co-sputtering process and found to be stable up to 600°C in air for extended periods of time through an exhaustive materials and electrochemical study. A percolation theory model was utilized to guide the design of the Pt/YSZ composition, allowing for a networked connection of ionic- and electron-conduction through the membrane, leading to an extension of the triple phase boundary (TPB). The Pt/YSZ composite deposition pressure was found to be a key in helping to stabilize the morphology of the film. By increasing the deposition pressure, this led to the formation of intergranular void spacing, or porosity, as well as a reduction of film strain in the post-annealed film. Surface analyses of the composite film demonstrated that the lower film strain led to a minimization of Pt hillock grain coarsening and de-wetting, even after exposure to high temperatures (600°C) for extended periods of time (tested up to 24hrs) in air. Analyses of the Pt/YSZ composite microstructure and composition by TEM confirmed an interconnected network of Pt and YSZ was maintained through the film’s thickness after exposure to high temperatures in air. A significant improvement in the stability of the electrical conductivity was demonstrated relative to the Pt electrodes, tested under constant current measurement conditions for up to 24hrs at 600°C. mSOFC testing results revealed that interconnectivity or percolation of the Pt and YSZ through the composite cathode was achieved, effectively leading to an increase in the TPB length, or increase in reaction sites for the oxygen reduction reaction to occur. The activation energy associated with the oxygen reduction reaction charge transfer kinetics in the Pt/YSZ was shown to be lower than a pure porous Pt electrode, along with a significant improvement in stability of the morphology during extended mSOFC operation. Mass diffusion of oxygen through the cathode to the TPB was found to be the rate determining step in the oxygen reduction reaction process. A further increase in porosity in the Pt/YSZ cathode should result in more efficient oxygen diffusion and a higher performance mSOFC cathode.

Committee:

Raj Singh, Sc.D. (Committee Chair); Relva Buchanan, Sc.D. (Committee Member); Hong Huang, Ph.D. (Committee Member); Rodney Roseman, Ph.D. (Committee Member)

Subjects:

Materials Science

Keywords:

micro fuel cell;solid oxide fuel cell;composite;thin film;nanomaterial;sputtering

Endo, MakotoNumerical modeling of flame spread over spherical solid fuel under low speed flow in microgravity: Model development and comparison to space flight experiments
Doctor of Philosophy, Case Western Reserve University, 2016, EMC - Mechanical Engineering
Flame spread over solid fuel presents distinctive characteristics in reduced gravity, especially when the forced flow velocity is low. The lack of buoyancy allows a blue, dim flame to sustain where the induced velocity would otherwise blow it off. At such low velocities, a quenching limit exists where the soot content is low and the effect of radiative heat loss becomes important. The objective of this study is to establish a high fidelity numerical model to simulate the growth and extinction of flame on solid fuels in a reduced gravity environment. The great importance of the spectral dependency of the gas phase absorption and emission were discovered through the model development and therefore, Statistical Narrow-Band Correlated-k (SNB-CK) spectral model was implemented. The model is applied to an experimental con figuration from the recent space experiment, Burning And Suppression of Solids (BASS) project conducted aboard the International Space Station. A poly(methyl methacrylate) (PMMA) sphere (initial diameter of 2cm) was placed in a small wind tunnel (7.6cm x 7.6cm x 17cm) within the Microgravity Science Glovebox where flow speed and oxygen concentration were varied. Data analysis of the BASS experiment is also an important aspect of this research, especially because this is the first space experiment that used thermally thick spherical samples. In addition to the parameters influencing the flammability of thin solids, the degree of interior heat-up becomes an important parameter for thick solids. For spherical samples, not only is the degree of internal heating constantly changing, but also the existence of stagnation point, shoulder, and wake regions resulting in a different local flow pattern, hence a different flame-solid interaction. Parametric studies using the numerical model were performed against (1) chemical reaction parameters, (2) forced flow velocity, (3) oxygen concentration and (4) amount of preheating (bulk temperature of the solid fuel). Flame Spread Rate (FSR) was used to evaluate the transient effect and maximum flame temperature, standoff distance and radiative loss ratio were used to evaluate the spontaneous response of the gas phase to understand the overall response of the burning solid fuel. After evaluating the individual effect of each parameter, the efficacy of each parameter was compared. Selected results of this research are: [1] Experimental data from BASS and numerical simulation both showed that within the time period between ignition until the flame tip reaches the shoulder of the sample, the flame length and time have almost a linear relation. [2] Decreasing forced flow velocity increases the radiative loss ratio whereas decreasing oxygen mole fraction decreases the radiative loss ratio. This fi nding must be considered in the effort to replicate the behavior of flame spread over thick solid fuels in microgravity on earth. [3] Although the standoff distance will increase when the forced flow velocity is decreased as well as when the oxygen mole fraction is decreased, the forced flow velocity has a much stronger effect on the standoff distance than the oxygen mole fraction. [4] Unlike the previous two comparisons, the effect of forced flow velocity and oxygen mole fraction on the maximum flame temperature was at similar level, reduction of either parameter would result in lowering the maximum flame temperature. [5] The effect of preheating on the flame spread rate becomes stronger when either the oxygen flow rate or forced flow velocity becomes larger. Depending on which element is more important, we can distinguish oxygen flow rate driven flame spread from preheating driven flame spread. Findings of this research are being utilized in the design of the upcoming space experiment, Growth and Extinction Limits of solid fuel (GEL) project. This research is supported by the National Aeronautics and Space Administration (NASA). This work made use of the High Performance Computing Resource in the Core Facility for Advanced Research Computing at Case Western Reserve University and the Ohio Supercomputer Center.

Committee:

James S. T'ien (Committee Chair); Yasuhiro Kamotani (Committee Member); Fumiaki Takahashi (Committee Member); Erkki Somersalo (Committee Member)

Subjects:

Aerospace Engineering; Mechanical Engineering

Keywords:

Numerical modeling; flame spread; solid fuel; spherical fuel; microgravity; combustion; space experiment; NASA; GEL; SoFIE; SNB-CK; Radiation; Heat transfer; Finite Element; FEM; FDS; Microgravity Experiment; NASA-STD-6001; BASS; SIFI; FSR; axisymmetric;

Stuckey, Philip A.Kinetic Studies and Electrochemical Processes at Fuel Cell Electrodes
Doctor of Philosophy, Case Western Reserve University, 2011, Chemical Engineering
Kinetic parameters that describe the operating efficiency and rate of a reaction are revealed in situ by applying normal pulse voltammetry to normally operating proton exchange membrane fuel cells. The Tafel slope for the oxygen reduction reaction is directly extracted from the steady state chronoamperometric response. Conditioning potential, temperature, and relative humidity are varied independently to observe their effect on the Tafel slope. Aqueous ex situ techniques commonly used to collect kinetic data only mimic the conditions within fuel cell and are unable to capture true operating processes, especially the effects of relative humidity. The observed Tafel slopes are 47-62 mV/decade for oxide covered platinum indicating a smaller activation overpotential than that for oxide free platinum with Tafel slopes of 91-119 mV/decade in initial studies. High temperature operation at 120°C showed no kinetic or mechanistic benefit compared to fuel cell operation at 80°C. If high efficiency is desired, the fuel cell should be operated in a potential range where oxide is present on the platinum surface. A novel technique is presented using pulse voltammetry measure platinum oxide coverage in situ on PEMFC electrodes. A linear logarithmic rate was noticed for oxide conditioning times longer than 1 second. Extended testing of relative humidity effects at 80 °C, combined with electrochemical active surface area measurements to normalize the oxide growth, showed a growth rate of 28 μC cm-2 (log s)-1 and also provided the ability to monitor platinum dissolution from the electrode. Concepts from both these projects are assimilated to develop novel pulse voltammetry waveforms that are applied in situ on normally operating proton exchange membrane fuel cells to reveal Tafel kinetics with control of adsorbed oxide on platinum. The results show that the Tafel slope decreases with increasing platinum oxide coverage on the electrode. The oxidation of higher order polyols such as glycerol would have profound impacts in the fuel cell arena considering the abundance of glycerol and its low price in the marketplace. Glycerol would provide a fuel with higher energy density than hydrogen. Preliminary results from glycerol oxidation studies on Pt, Pt-Ru, and Pt-Cr are reported.

Committee:

Thomas Zawodzinski, Jr. (Advisor); Jay Mann, Jr. (Committee Chair); Mohan Sankaran (Committee Member); David Schiraldi (Committee Member)

Subjects:

Alternative Energy; Analytical Chemistry; Chemical Engineering; Energy; Engineering; Mechanical Engineering

Keywords:

Fuel cell; electrochemistry; pulse voltammetry; Tafel slope; oxygen reduction reaction; platinum; oxide; in situ; kinetics; proton exchange membrane fuel cell; normal pulse voltammetry; chronocoulometry; chronoamperometry; glycerol; hydrogen

Gaone, Joseph MichaelA Mathematical Model of a Microbial Fuel Cell
Master of Science, University of Akron, 2013, Applied Mathematics
In this study a microbial fuel cell (MFC) computational model is developed. The purpose is to establish a one dimensional MFC model, at steady state, that contains a biofilm, anode, membrane, and cathode region and uses a conductive biofilm matrix that depends on pH. Biomass equations, chemical equations, and potential equations are developed to model the operation of each compartment. Numerics are utilized to solve the various sets of ordinary and partial differential equations. We examine the efficiency and optimization of this MFC. A parameter study was performed on this model to compare the results to previous models and experiments for validation and to observe the effects of new contributions. The results show that a non-constant conductivity is vital to MFC operation if large variation in pH is expected. Applied potential was found to be optimal at the lowest possible value that does not inhibit electron transport to the cathode. Electric potential can be maximized by making the distance between electrodes as small as possible to reduce the resistance. These features are essential in order to maximize efficiency and power output of an MFC. This model and investigation are significant because it unifies previously separate anode and cathode models as well as establish the basis of including pH dependent non-constant conductivity in MFC models.

Committee:

Gerry Young, Dr. (Advisor); Curtis Clemons, Dr. (Advisor); Kevin Kreider, Dr. (Advisor); J. Patrick Wilber, Dr. (Advisor)

Subjects:

Biochemistry; Mathematics

Keywords:

MFC; microbial fuel cell; conductive biofilm matrix; biofilm; fuel cell; mathematical model; computational model; model; nanowire; conductive nanowires

Guzman Montanez, FelipeElectrochemical and Photocatalytic Oxidation of Carbon and Hydrocarbons
Doctor of Philosophy, University of Akron, 2009, Chemical Engineering

Development of novel technologies for the conversion and storage of energy has been actively investigated in recent years. The use of a combined approach consisting of direct electrochemical and photocatalytic oxidation reactions could allow the efficient utilization of energy resources. Direct electrochemical oxidation in a fuel cell could offer significant advantages over conventional combustion technologies, in light of their increased energy efficiency, reduction in emission of toxic pollutants, and overall process simplicity. The majority of fuel cell research has focused on the use of hydrogen, an environmentally friendly fuel characterized by high energy density and production of H2O byproduct. Despite these advantages, commercialization of hydrogen powered fuel cells is currently limited by difficulties in hydrogen production and storage.

The high operation temperature of the solid oxide fuel cell (700-1000 °C) facilitates the direct use of hydrocarbon and carbon fuels, avoiding the complex and expensive reforming processes for the generation of concentrated H2 fuel. Exposure of gaseous hydrocarbons to the fuel cell at these high temperatures provides a thermodynamically favorable pathway for formation of carbon deposits (i.e., coking) which can lead to rapid and irreversible anode electrode degradation. This dissertation presents a study of the use of a novel Cu/Ni-YSZ anode electrode that reduces the formation of coke deposits and allows the energy efficient operation of the solid oxide fuel cell in hydrocarbon and carbon fuels. The microstructure of the Cu/Ni-YSZ anode electrode is extensively characterized by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The performance of the Cu/Ni-YSZ anode and the energy efficiency during the operation on carbon (i.e., coke, a devolatized form of coal) is experimentally measured with the aid of in situ electrochemical analysis and, mass spectrometry (MS) and gas chromatograph (GC), demonstrating higher energy efficiencies compared with combustion technologies.

Photocatalytic reactions over semiconductor catalysts such as TiO2 have received significant attention due to their potential applications for conversion and storage of solar energy to chemicals and the degradation of harmful pollutants present in air streams and wastewaters. Excitation of photocatalysts by exposure to light of appropriate energy causes promotion of electrons from the valence band to the conduction band, resulting in the generation of electron/ hole pairs that can initiate redox reactions with species adsorbed on the surface of the photocatalyst. Hydrogen can be produced by the photocatalytic reduction of water (i.e. splitting reaction). Addition of alcohol molecules have been shown to improve the photocatalytic evolution of H2 from H2O due to hole scavenging oxidation reactions that limit electron/hole recombination. Detail knowledge of the mechanisms governing the photocatalytic oxidation of alcohols could facilitate the development of highly efficient photocatalysts for water splitting and degradation of volatile organic compounds (VOC).

The photocatalytic evolution of H2 from aqueous solutions containing methanol (CH3OH) hole scavenging reagents was studied by tracing the reaction of D2O over a Cu/S-TiO2 catalyst under UV illumination. Use of D2O/CH3OH produced higher formation rates of HD and D2 than that of H2. The low H2 formation rates indicate that the direct reaction of CH3OH with photogenerated holes does not proceed to an appreciable extent in the presence of high concentrations of D2O. The role of CH3OH in accelerating hydrogen formation can be attributed to its ability to produce an electron donor, injecting its electrons to the conduction band.

The photocatalytic oxidation of alcohols was further studied at 30 °C and 1 atm by in situ infrared methods, using ethanol as a model compound. Results from these studies have shown ethanol adsorbs on TiO2 in the presence of high contents of water as molecularly adsorbed ethanol (CH3CH2OHad), which exhibit a lower initial C-H scission and CO2 formation rate than ethoxy CH3CH2Oad produced from ethanol adsorbed low water content TiO2 catalysts. CH3CH2OHad photooxidation produced formic acid (HCOOHad) and formate (HCOO-ad) species, whereas CH3CH2Oad reactions proceed via formation of acetaldehyde (CH3CHOad) and acetate (CH3COO-ad). CH3CHOad was found to react on TiO2 via hydrogen abstraction of the -Carbon producing CH3COO-ad which can be further oxidized to HCOO-ad and CO2. The rate of ethanol photooxidation was found to decrease due to the accumulation of CH3COO-ad species on the TiO2 surface. In the presence of excess H2O, weakly adsorbed species (i.e., acetic acid CH3COOHad) can be redistributed in the surface and dissociated producing acetate.

Committee:

Steven S. Chuang, PhD (Advisor)

Subjects:

Chemical Engineering

Keywords:

fuel cell; fuel; TiO2; PHOTOCATALYTIC; anode; PHOTOCATALYTIC OXIDATION; H2O

Ghosh, UjjalOne dimensional modeling of planar solid oxide fuel cell
Master of Science (MS), Ohio University, 2005, Mechanical Engineering (Engineering)
Using modeling and simulation, the present work offers parametric study for Planar Solid Oxide Fuel Cell (PSOFC) as a function of fuel gas composition. The study comprises of one-dimensional steady and dynamic state modeling of single PSOFC in Aspen Custom Modeler. The simulations are performed at the interface of fuel channel and anode, and the reaction kinetics, the spatial distributions of temperature and specie concentrations inside the PSOFC are calculated. Steady state model estimates the cell performance as function of CO, and the dynamic model estimates the transient performance degradation, due to Area Specific Resistance (ASR) degradation. Additionally, the dynamic model analyzes the sensitivity of cell performance on input variables, and recovery time for the small variations. The analysis shows that temperature, current density, flow-rate, ASR and fuel composition affect the cell performance. At low current densities, the cell performances are comparable, up to 80% CO in the fuel gas.

Committee:

David Bayless (Advisor)

Subjects:

Engineering, Mechanical

Keywords:

One Dimensional Modeling; Planar Fuel Cell; Solid Oxide Fuel Cell

Kauffmann, Joseph ChesterInvestigation of the influence of gasoline engine induction system parameters on the exhaust emission
Doctor of Philosophy, The Ohio State University, 1972, Mechanical Engineering

Committee:

Helmuth Engelman (Advisor)

Keywords:

MANIFOLD; ENGINE; Fuel; EXHAUST; Fuel Ratios; API; Cylinder

Allen, Christopher T.Global Optimization of an Aircraft Thermal Management System through Use of a Genetic Algorithm
Master of Science in Engineering (MSEgr), Wright State University, 2008, Mechanical Engineering

Optimization algorithms utilize known information about the system to identify solutions that are more efficient and meet the requirements of the user. The algorithms require an objective function, or formula (linear or nonlinear) that models what the user is looking to optimize, in order to begin the search for a more feasible solution. Because optimization problems can involve either linearor non-linear functions, various algorithms have been created that can locate optimum solutions faster depending on the type of objective function being optimized.

This research focuses on optimizing an aircrafts thermal management system by using one such algorithm. This was performed in a three step process: initial research and testing, algorithm search method implementation, and post processing and analysis. The aircraft was modeled using complex Matlab Simulink block diagrams to simulate the thermal response of the system for any given type of mission. Using the provided parametric data, areas of user control within the model were located and optimization methods for these areas were devised. The function characterizing the fuel feed temperatures was chosen as the objective function to be minimized. Baseline data proved the function to be nonlinear. Optimization software incorporating a genetic algorithm (GA) was chosen since they are known to be best suited for nonlinear objective functions.

Optimization method implementation results showed a decrease in fuel temperature and convergence times. Data pulled from the GA detailed feasible fuel drainage sequences that would reduce fuel temperatures to 132F from the baseline temperature of 143F. Currently, methods using smaller drain sequences have been unable to match these results due to the coarse control over the fuel drainage these sequences provide. Because numerous computations are ran during each test, only feasible sequences shown to decrease the temperature were validated. Results show a need for physical hardware testing to verify the computational results shown.

Committee:

Joseph C. Slater, PhD (Advisor); Thomas Baudendistel, PhD (Committee Member); J. Mitch Wolff, PhD (Committee Member); George P. Huang, PhD (Other); Joseph F. Thomas, Jr., PhD (Other)

Subjects:

Engineering

Keywords:

x_DHO; Tanks; drain sequences; dot; fuel; drain; fuel temperature

Garcia, Andrew MichaelFeed-Forward Air-Fuel Ratio Control during Transient Operation of an Alternative Fueled Engine
Master of Science, The Ohio State University, 2013, Mechanical Engineering
With the increasing government regulations for higher vehicle fuel economy and lower tailpipe emissions, today’s automotive engineers are pushed to develop advanced vehicles. Further, due to the high prices of oil, the consumer market is demanding for more fuel efficient vehicles. To adapt to the increasing demands, automotive manufacturers have been investing in the research of advanced vehicle technologies. The work described in this thesis details the development of a methodology to improve the feed-forward air-fuel ratio control during transient operation of an alternative fueled engine. Due to transport delays between the induction of the air-fuel mixture into the cylinder and the reading of the combustion exhaust gases from the oxygen sensor, conventional feedback control cannot be accurately used in transient operation. Since the engine used in this thesis is port-fuel injected, the fuel injection is made a discrete amount of time before the intake valve opening. This gives the fuel time to vaporize in the intake runner before being inducted. Therefore, in order to achieve stoichiometric combustion, the amount of inducted air will have to be determined a discrete amount of time into the future. This work outlines the development of a control algorithm that improves the transient air-fuel ratio control by predicting the intake manifold air pressure forward in time. Using model-based calibration techniques and engine dynamometer data, an intake manifold model was created. Coupling this model with a Forward Euler approximation, a predictive intake manifold pressure algorithm was developed. Adaptive models were implemented into the control algorithm to account for day-to-day variations in engine operation as well as calibration errors in the intake manifold model. The algorithm was verified in software validation with a mean value engine model and hardware validation in the engine dynamometer test cell. With the implementation of the predictive control algorithm, there was a vast improvement in air-fuel ratio control performance over the engine’s previous control strategy. Oxygen sensor results showed a significant reduction in deviations from stoichiometric combustion, allowing the three-way catalyst to operate in its most efficient range. The research detailed in this thesis shows the effectiveness of using a model-based approach to air-fuel ratio control and the importance of adaptive algorithms for day-to-day changes in engine operation.

Committee:

Shawn Midlam-Mohler, Dr. (Advisor); Giorgio Rizzoni, Dr. (Committee Member)

Subjects:

Automotive Engineering; Mechanical Engineering

Keywords:

air-fuel ratio control; tailpipe emissions reduction; feed-forward air-fuel ratio control; model-based calibration; intake manifold modeling; Forward Euler approximation

Shi, LimingComputational Fluid Dynamics Simulation of Steam Reforming and Autothermal Reforming for Fuel Cell Applications
Master of Science (MS), Ohio University, 2009, Chemical Engineering (Engineering and Technology)
With the increasing demand for fuel cell applications in transportation, the performance of reformers using gasoline or diesel as the fuel needs to be optimized. Numerical models based on computational fluid dynamics (CFD) were used to simulate the performance of these reformers. A CFD model of steam reforming and a CFD model of autothermal reforming were developed and validated for two reformers. Each model included submodels for the reactor and reaction chemistry. A single channel was used in the model of steam reforming and a whole reactor was modeled in the model of autothermal reforming. A reaction rate expression was developed for the steam reforming reaction to form hydrogen and carbon dioxide. The CFD results provided an adequate match to the experimental data from the literature. The percentage of difference between each experimental measurement of the mole fraction of hydrogen and the corresponding CFD prediction was less than 17.7% for the model of steam reforming and 16.8% for the model of autothermal reforming. The CFD models were used to predict reformer performance. For steam reforming, the inlet steam-to-carbon molar ratio had a negligible effect on reforming efficiency when it was varied from 2 to 4. The reforming efficiency decreased slightly as the inlet velocity was increased from 2.9 to 8.7 m/s, which was mainly caused by the steam reforming reaction. For autothermal reforming, the thermal conductivity of the catalyst support affected the temperature profile in the reactor, but its effect on the mole fraction of hydrogen in the products was negligible. The reforming efficiency decreased by 11.5% as power input was increased from 1.7 to 8.4 kW.

Committee:

Michael E. Prudich (Advisor)

Subjects:

Chemical Engineering; Energy

Keywords:

Steam Reforming; Autothermal Reforming; CFD; Modeling; Fuel Processing; Fuel Cells

Ramirez, Steven AbrahamSupervisory Control Validation of a Fuel Cell Hybrid Bus Using Software-in-the-Loop and Hardware-in-the-Loop Techniques
Master of Science, The Ohio State University, 2013, Mechanical Engineering
The work presented within this thesis consists of the validation of a supervisory controller and vehicle simulator for the ECO Saver IV demonstration bus being developed as part of the National Fuel Cell Bus Program (NFCBP). The goal of the NFCBP is to develop fuel cell transit buses such that a U.S. industry for fuel cell bus technology can be established through both technology innovation and increased public awareness of fuel cell vehicles. The use of fuel cells in vehicles is desirable due to their high efficiencies and zero emissions, allowing the transportation sector to rely less heavily on petroleum and carbon based fuels that emit hazardous greenhouse gases. The ECO Saver IV, as designed by the DesignLine Corporation through a contract with the Center for Transportation and the Environment, is a battery dominant fuel cell hybrid bus that takes advantage of the benefits of hybridization in conjunction with the benefits of the fuel cell. The team of researchers at The Ohio State University (OSU) Center for Automotive Research (CAR) served as a subcontractor to develop a supervisory controller and fuel cell hybrid bus simulator, modeled after the chosen powertrain architecture. The validation performed involved the use of software-in-the-loop and hardware-in-the-loop simulations, where the results were compared to baseline model-in-the-loop simulations. The driving conditions of the intended application of the demonstration bus, i.e., integration into the OSU Campus Area Bus Services (CABS) fleet, were taken into consideration through the development of real-world drive cycles that were representative of actual CABS bus routes. A new driver model was developed that solved issues related to tracking distance, velocity and road grade to enable the use of real-world drive cycles. The results of the validation are to be used in the final phases of development and construction of the ECO Saver IV fuel cell hybrid transit bus to prove the effectiveness of using the developed control algorithm within the bus’ control hardware. To aid in the evaluation phase of the demonstration bus project, a CAN based data acquisition system was developed and tested on the HIL test bench. The logged data will be used to evaluate the successfulness of the fuel cell hybrid transit bus while providing evidence of the viability of such a vehicle.

Committee:

Shawn Midlam-Mohler, Dr. (Advisor); Yann Guezennec, Dr. (Committee Member)

Subjects:

Automotive Engineering; Engineering; Mechanical Engineering

Keywords:

Fuel Cell; Hybrid; Bus; Hardware in the Loop; HIL; Software in the Loop; SIL; supervisory control; data acquisition; National Fuel Cell Bus Program; real world drive cycle

McHenry, John Carl IzaakThe Challenges of Biofuels in Ohio: From the Perspective of Small-Scale Producers
Master of Science (MS), Ohio University, 2008, Environmental Studies (Arts and Sciences)

The increased interest in renewable biofuels, such as biodiesel and ethanol, has come in the wake of higher domestic fuel costs after many years of low consumer prices. With the increase in the price of petroleum-based fuels and growing concern over the reliance on foreign oil from unstable parts of the world there has been more interest to look for cheaper, more sustainable energy resources.

While domestically produced sustainable energy sources have the potential to spur growth for domestic farming communities, they have also been touted as being more environmentally friendly. There is also discussion about the potential for biofuels powering a large number of vehicles for the United States transportation sector while producing lower emissions and greenhouse gases. Some see this as a way to help reduce the effects of global warming but issues such as the availability of limited feedstock to produce the biofuels and bigger pictures such as food versus fuel are also a growing concern.

There are technical drawbacks to biofuels such as decrease in power, solvency issues, public perception, price competitiveness, feedstock availability, the waste stream produced and whether or not this waste can be dealt with in a sustainable manner. There are also issues related to the net energy gain from producing biofuels, which must also be addressed.

In terms of acres harvested, Ohio is one of the top ten agricultural states in the country and produces significant amounts of corn and soybeans, the main feedstock for biofuels. Many view biofuels as a way to stimulate the state economy while producing a more environmentally friendly domestic fuel. With new alternative fuels there are certain challenges in order to make these fuels more widely available. In this thesis I will explore the challenges of biofuels from the perspective of small-scale producers in Ohio that have a production rate of less than 5 million gallons per year.

Committee:

Michele Morrone (Advisor)

Subjects:

Environmental Sciences

Keywords:

Biofuels; Biodiesel; Ethanol; renewable fuel; alternative fuel; Ohio

Kazungu, Conny SidiAssessing the Energy Efficiency of Small Transit Systems; A Case Study of the Miami Metro Bus Service
Master of Science, Miami University, 2012, Environmental Sciences
In the recent past there has been an emphasis on energy and fuel efficiency in transit systems across the United States. Transit systems continue to attempt to reduce their greenhouse gas emissions while enhancing efficiency and aiming to do so in a cost-effective manner. This study which was conducted in the months of May- August 2011 looks at a small transit system, the Miami Metro Bus Service, which serves the students, faculty and staff of Miami University in Oxford, Ohio. In determining the relationship between route planning and energy efficiency, the existing bus routes and the proposed changes to the bus routes are analyzed. The key factors which are used in this analysis include; the total miles driven, energy savings, fuel costs savings (mpg) and emissions (GHG) associated with the existing and the proposed bus routes. The results indicate the proposed changes to the bus routes are more fuel and energy efficient.

Committee:

David Prytherch, PhD (Advisor); Steve Elliott, PhD (Committee Member); Sandra Woy-Hazleton, PhD (Committee Member)

Subjects:

Energy; Environmental Science; Sustainability; Transportation; Transportation Planning

Keywords:

Energy efficiency;fuel efficiency;small transit systems;total miles driven;energy savings;fuel cost savings;emissions;GHG;Miami Metro

Baderuddin, Feroze KhanMicroextrusion 3D-Printing of Solid Oxide Fuel Cell Components
Doctor of Philosophy in Materials Science and Engineering, Youngstown State University, 2016, Department of Chemistry
The aim of this research was to investigate microextrusion 3d printing which is a type of Additive Manufacturing (AM) technique for the fabrication of a solid oxide fuel cell. The solid oxide fuel cell or SOFC is a fuel cell for which the electrolyte consists of an O2--conducting metal oxide. They have proven to be an efficient and cost effective method for conversion for a wide variety of fuels such as hydrocarbons, coal gas and gasified carbonaceous solids into electricity. An SOFC typically is operated from around 600-1000 °C, hence, its needed to be made of ceramic components. Current ceramic technologies of fabrication limit SOFC design options and ultimate efficiencies. On the other hand, 3D printing technology enables intricate geometries which could provide higher levels of performance. An SOFC consists of three main components: electrolyte, cathode and an anode. The respective materials of choice were 8%Y2O3-ZrO2 (YSZ), Sr-doped LaMnO3 blended with 50 % YSZ and (40%)Ni/(60%)YSZ cermet. Paste formulations were prepared for each of the SOFC components and test disks or buttons were 3d printed. Various printed layers of an SOFC were evaluated according to ionic conductivity, electronic conductivity, gas permeability, density and shrinkage. By varying the compositions of the pastes according to particle size, binder ratio and solvent paste viscosity and consistency was controlled. The formulation pastes of all the components of the SOFC were designed to achieve uniform shrinkage upon cosintering at 1300 °C. The functionality of the 3d printed fuel cell was demonstrated by testing its galvanic performance and the microstructure was verified under an SEM.

Committee:

Clovis Linkous, PhD (Advisor); Sherri Lovelace-Cameron, PhD (Committee Member); Tim Wagner, PhD (Committee Member); Guha Manogharan, PhD (Committee Member); Brett Conner, PhD (Committee Member)

Subjects:

Chemical Engineering; Chemistry; Energy; Engineering; Inorganic Chemistry; Materials Science; Nanoscience; Nanotechnology; Sustainability

Keywords:

Solid Oxide Fuel Cells; Additive Manufacturing; 3D Printing; Co-Sintering; Nanoparticles; SOFCs; Fuel Cells

Dell, Twyla J.Flame, Furnace, Fuel: Creating Kansas City in the Nineteenth Century
Ph.D., Antioch University, 2009, Antioch New England: Environmental Studies
Though this work is a fuel and energy history of Kansas City from 1820 to 1920, it also provides a tool to describe and analyze fuel and energy transitions. The four parts follow the rise and fall of wood, coal and oil as their use grows to a peak and, in the case of wood, declines. The founding and growth of Kansas City as an “instant city” that grew from zero population to over three hundred twenty thousand in a hundred years embodies the increased use of fuels and energy in an urban setting and serves as a case study. This work differentiates between these two elements throughout the one-hundred-year-history to offer a clarification in terminology and theory. The narrative begins in the Wood age, continues to the peak of the Coal Age and introduces the Oil Age as it was to 1920.

Committee:

Alesia Maltz, Ph.D. (Committee Chair); Thomas N. Webler, Ph.D. (Committee Member); Martin V. Melosi, Ph.D. (Committee Member)

Subjects:

Environmental Studies

Keywords:

energy history; fuel history; urban history; instant cities; environmental history; Wood Age; Coal Age; Oil Age; model for description and analysis of fuel history

Tanim, Tanvir R.Modeling of a 5 kWe Solid Oxide Fuel Cell Based Auxiliary Power Unit Operating on JP-8 Fuel
Master of Science (MS), Ohio University, 2012, Mechanical Engineering (Engineering and Technology)

Solid Oxide Fuel Cells (SOFC) offer potential for high conversion efficiency, high energy utilization, low emissions and quiet operation. Because of the cost associated with hydrogen storage, coupling an onboard fuel reformer with a SOFC stack is an attractive option for small decentralized and Mobile Electric Power (MEP) generation and as an Auxiliary Power Unit (APU) for motor vehicles. In this study Aspen Plus simulation software is used to develop a 5 kWe APU model using JP-8 as a fuel. JP-8 is selected because of its near ubiquitous use by the U.S. Army and Air Force for ground and air operations. The SOFC platform is selected due to its inherent advantages including: high fuel conversion efficiency, compact design, low noise and emissions. In this study desulfurized JP-8 surrogate fuel is reformed in an onboard autothermal reformer (ATR). The resultant H2 and CO mixture is used as fuel for the SOFC stack. The steam rich anode exhaust is recycled to supply the ATR with thermal energy and steam required to reform the fuel. Such an implementation makes the proposed system lighter and more compact, avoiding the need for an external steam generator and additional heat source for the ATR” (Tanim & Bayless, 2011). Ni-YSZ based tubular and planar SOFC stacks operating at 910 °C and 850 °C, respectively are evaluated as part of the study. ATR performance from 700 °C to 850 °C in the H2O/C ratio range of 0.10-1.0 is investigated.

The tubular cell based system (T-SOFC) showed a maximum net AC efficiency of 39.55% at 700 °C reformer temperature and a minimum of 32.60% at 850 °C. The planar cell based system (P-SOFC) demonstrated a maximum and minimum efficiency of 37.10% and 29.20% at 700 °C and 800 °C reformer temperatures, respectively. Sensitivity analyses are conducted evaluating the effect of the fuel utilization factor (Uf) and the current density (j) to determine optimum system operating windows. Finally, the T-SOFC and P-SOFC systems are compared and the results are analyzed in terms of voltage, net AC efficiency and power density. The anode supported P-SOFC system demonstrated a higher operating current density range achieving higher efficiency and power density compared to T-SOFC system.

Committee:

Jason Trembly, PhD (Committee Chair); David Bayless, PhD (Committee Co-Chair); Gregory Kremer, PhD (Committee Member); JungHun Choi, PhD (Committee Member); Hugh Richardson, PhD (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

JP-8 Fuel; Autothermal Reformer; Solid Oxide Fuel Cell

Moda, Sunil Udaya SimhaComputational Modeling and Analysis of Heavy Fuel Feasibility in Direct Injection Spark Ignition Engine
Master of Science in Engineering (MSEgr), Wright State University, 2011, Mechanical Engineering

Direct Injection spark ignition (DISI) technology is helpful for the present day engine to increase the fuel efficiency. Power output and the choice of fuel as the demand and scarcity for fossil fuels are increasing. As a new technology DISI engines are employed in some commercial cars like the Pontiac Solstice using gasoline fuel. The advantages of DISI engines like use of different fuels, reduced compression ratio, reduced injection pressure and reduced operating pressures in DISI engines has not been widely tested. As a new technology DISI engines lack experimental results and combustion co-relations that can be directly used as in the case of conventional engines. The experimental analysis of this technique is very expensive as it involves large number of parameters to be changed each and every time the experiment is done. This makes the experimental analysis of DISI engine a costly and time consuming task. Computational fluid dynamics on the other hand can simulate the combustion process and let researches visualize the process of combustion inside the cylinder.

The ability of DISI engine to work on different fuels in the engine is successfully tested. Two engines, reciprocating and rotary, equipped with DISI technology is simulated in FLUENT. The engines are selected in such a way that they represent the major part of engine family to show that DISI technology is feasible in any type of IC engines. Because of unavailable experimental data on DISI diesel engines, the models used in the thesis are validated with a gasoline DISI reciprocating engine. The validated model is used for parametric study of diesel fuel in DISI engine. It was found that the engine parameters need to be tuned to avoid the undesired effects of diesel fuel. After several parametric changes, combustion and power output which is identical to the experimental validated case are obtained. Hence it has been proved that the diesel fuel can be successfully utilized in DISI engine. This technology is then applied to the rotary engine. Because of the change in geometry and many other specifications, the parameters used for reciprocating engine are not feasible for rotary engine. Therefore a parametric study on rotary engine is carried out to obtain a good combustion and power output.

It is proven successfully in this thesis that DISI technology can be applied to any engine and can use any kind of fuel. However, each and every engine needs to be tuned according to its specifications and geometrical constrains to obtain the maximum fuel to air mixture and therefore the maximum power output. The thesis explains the influence of parameters on the power output considering the important properties of fuel such as cold start ability, flash point detonation, volatility and density. The behavior of fuel and flow physics inside the cylinder is visually explained. The fuel air interaction, which is very important to have a good air fuel mixture formation, is extensively studied and the methods are developed to time the injector depending on the air turbulence inside the cylinder. The conclusions in this thesis demand the importance of further studies of this technology. The results of the thesis show that this technology can be used as a more energy efficient and echo friendly technology. However, further studies on this technology are essential to build a flawless more efficient technology in the field of IC engines.

Committee:

Haibo Dong, PhD (Committee Chair); Greg Minickweicz, PhD (Committee Member); Hui Wan, PhD (Committee Member); George Huang, PhD (Other); Andrew Hsu, PhD (Other)

Subjects:

Engineering

Keywords:

Direct Injection Spark Ignition; Reciprocating Engine; Solstice; Multiple Plume Injection; Rotary Engine; DISI; Heavy fuel; Heavy Fuel Feasibility;Computatinal modeling;Parametric study

Stalcup, Erik JamesNumerical Modeling of Upward Flame Spread and Burning of Wavy Thin Solids
Master of Sciences, Case Western Reserve University, EMC - Aerospace Engineering
Flame spread over solid fuels with simple geometries has been extensively studied in the past, but few have investigated the effects of complex fuel geometry. This study uses numerical modeling to analyze the flame spread and burning of wavy (corrugated) thin solids and the effect of varying the wave amplitude. Sensitivity to gas phase chemical kinetics is also analyzed. Fire Dynamics Simulator is utilized for modeling. The simulations are two-dimensional Direct Numerical Simulations including finite-rate combustion, first-order pyrolysis, and gray gas radiation. Changing the fuel structure configuration has a significant effect on all stages of flame spread. Corrugated samples exhibit flame shrinkage and break-up into flamelets, behavior not seen for flat samples. Increasing the corrugation amplitude increases the flame growth rate, decreases the burnout rate, and can suppress flamelet propagation after shrinkage. Faster kinetics result in slightly faster growth and more surviving flamelets. These results qualitatively agreement with experiments.

Committee:

James T'ien (Committee Chair); Joseph Prahl (Committee Member); Yasuhiro Kamotani (Committee Member)

Subjects:

Aerospace Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

modeling;simulation;numerical modeling;combustion;computational combustion;direct numerical simulation;flame spread;burning;wavy;corrugated;fire dynamics simulator;FDS;fuel structure;fuel geometry;complex geometry;cardboard;

Meeboon, NonDesign and Development of a Porous Injector for Gaseous Fuels Injection in Gas Turbine Combustor
MS, University of Cincinnati, 2015, Engineering and Applied Science: Aerospace Engineering
A novel porous injector is designed for injection of gaseous fuel in land based gas turbine combustors. The injector is tested at atmospheric conditions at Combustion Research Laboratory, University of Cincinnati. In the present study, seven injector configurations are tested for mixing quality, LBO limits and emissions. For mixing studies, the CO2 technique is adopted to evaluate the fuel-air mixing under atmospheric conditions of the porous injector. The experiments are carried out at 4% pressure drop condition across the injector. The CO2 concentrations are converted to fuel mass fractions for the comparison. A comparison between the top/bottom injections, center/no center injection and 7/30 micron porous tubes show that these configurations do not impact the fuel-air mixing distribution. PIV measurements are carried out in non-reacting as well reacting conditions. Velocity profiles are obtained at a 1%-4% pressure drop condition. The experiments are carried out with and without combustor. A weak outer recirculation zone is observed downstream of the injector in the combustor. The velocity profiles are same at the exit plane of the injector with and without combustor. The velocity decreases gradually along the combustor. The ignition and lean blow out limit are observed to increase as the pressure drop increases. The flame liftoff distance is found to increase as the pressure drop increases. The NO, CO, and O2 emissions are evaluated at the downstream of the porous injector at 6" from the entrance of the combustor. The results show that the NOx emissions are ~ 7 ppm @ 15% O2.

Committee:

San-Mou Jeng, Ph.D. (Committee Chair); Umesh Bhayaraju, Ph.D. (Committee Member); Samir Tambe, Ph.D. (Committee Member)

Subjects:

Aerospace Materials

Keywords:

Porous;Injector;Gaseous fuel;Gas turbine;Combustor;Fuel-air mixing

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