Master of Science (MS), Ohio University, 2009, Mechanical Engineering (Engineering and Technology)

The increasing concerns related to long term availability of petroleum-based fuels and the emissions from diesel-powered vehicles have given rise to a growing search for an alternate source of fuels for use in diesel vehicles. One of the most recent and promising findings in this field is “Bio-diesel”. The thesis uses a comparative study of NOx emission characteristics for regular diesel fuel and soy based biodiesel for a four cylinder, 60 HP turbocharged diesel engine for validation of the engine and the emission test rig. Modifications are recommended for the current test setup and test procedure to enable research quality testing of Algae based biodiesel.

Committee: Gregory G Kremer (Advisor); David Bayless (Committee Member); Ben Stuart (Committee Member); Helmut Paschold (Committee Member) Subjects: Mechanical Engineering

MS, University of Cincinnati, 2001, Engineering : Environmental Engineering

This paper summarizes the findings of a study on the effect of the chemical and physical properties of Ohio coals on NO x emissions, as well as combustion conditions that promote lower levels of pollutant release. The results were obtained in a drop-tube reactor under controlled laboratory conditions with well-characterized samples of Ohio coals. Ten Coal samples were obtained from the Penn State Coal Sample Bank and selected based on their levels of fixed carbon, volatility and nitrogen content. The heat contents of the 10 coals were similar. Tests on monodispersed sized coal particles were conducted in the ceramic drop-tube reactor at 1200°C and a gas residence time of 0.5 sec. The diameter of the ceramic drop tube reactor was 5.08 cm and its length was 110.5 cm. The air/fuel (A/F) ratio was maintained at 1.1 and the coal feed rate was 7 – 9 mg/min. The percent nitrogen in the raw coal ranged from 1.24 to 2.5%wt. For a majority of the experiments, samples were prepared in sizes between 15 to 25 micrometers. From the experimental results, it was found that relative NO x emissions varied by as much as 100% and that a linear relationship exists between relative NO x formation and the chemical and physical properties of Ohio coals. NO x emissions depend on the properties of fixed carbon (FC), volatile matter (VM) and nitrogen (N) in the raw coals. As a result, relative NO x gas emissions were predicted, which may be useful in terms of coal selection for any source using Ohio coals.

Committee: Dr. Tim C. Keener (Advisor) Subjects: Engineering, Environmental

Doctor of Philosophy, The Ohio State University, 2005, Mechanical Engineering

Diesel engines require the use of alternative catalytic methods to meet future emissions standards. One such alternative system is the bypass-regeneration, Lean NOx Trap (LNT), which is the focus of this work. A novel method of providing reductants for management of this system is presented, which is referred to as flame reforming. This method uses rich, premixed combustion of Diesel fuel to generate carbon monoxide, hydrogen, and light-chain hydrocarbons for LNT management. Through the development of a prototype flame reformer and experimental testing, this concept is demonstrated to offer advantages over traditional methods in cost and dynamic response. A technique, which is referred to as exotherm analysis, is developed which allows the observation of chemical phenomena inside the catalyst using substrate temperature measurements. Through the proper analytical methods, it is demonstrated experimentally that the temperature rise in the catalyst can be correlated to the rate that key reactions are taking place, as well as the mass of NOx stored and the effects of sulfur poisoning. These key reactions include the reduction of stored oxidizers as well as the readsorption of oxygen by the catalyst. This technique is exclusive to the bypass-regeneration system because of the low gas flow rates involved. A control-oriented model of the storage and regeneration process is also developed. This model is used to develop a complete LNT NOx management algorithm using the techniques of model-based control. This algorithm, which uses catalyst temperatures as the primary feedback signals, contains an adaptive engine-out NOx estimator as well as an adaptive catalyst-out NOx estimator. In this way, the algorithm automatically compensates for sulfur poisoning of the catalyst. The model also is used to develop a virtual LNT system simulator with all of associated control algorithms and adaptive estimators. With this tool, the LNT management algorithm is evaluated for an intended Tie (open full item for complete abstract)

Committee: Yann Guezennec (Advisor) Subjects: Engineering, Automotive

Doctor of Philosophy, Case Western Reserve University, 2008, Biochemistry

The most well known receptor for NO is soluble guanylate cyclase (sGC), which converts guanosine-5'-triphosphate (GTP) to cyclic guanosine-3', 5'-monophosphate (cGMP) upon NO activation. cGMP serves as an important second messenger to regulate a wide range of physiological process in cardiovascular and neurological systems. This pathway is targeted for therapeutic purposes as Glyceryl trinitrate (GTN), which generates the signaling molecule NO inside the cell, has been used to treat angina pectoris and heart failure for more than a century. sGC is a heterodimeric hemoprotein composed of two different subunits: α (73-82 kDa) and β (70-76 kDa). Both subunits share a similar domain organization: an N-terminal domain (which harbors a heme only in β1 called H-NOX), a central H-NOXA domain, a Coiled-coil (CC) domain and a C-terminal guanylyl cyclase domain. An appreciation of the atomic details of the mechanism by which NO activates sGC is critical to our understanding of how such a small gaseous molecule NO is able to recognized by the target cell and in turn elicit a wide variety of responses. This thesis is focused on the structural characterization of H-NOX domain, H-NOXA domain and CC domain, little structural information was available by the time this project was initiated. The first target was the stand-alone H-NOX domain from Nostoc sp PCC 7120, which shares 33% sequence identity with human sGCβ1. We have determined three Ns H-NOX structures including unliganded, NO bound and CO bound form at 2.1A, 2.5A and 2.6A respectively. We have identified a critical aromatic residue above the heme plane conferring binding advantage to NO over CO by steric hindrance. Comparison of these structures and previously published Tt H-NOX structure has revealed a heme pivot-bend mechanism that correlates with the H-NOX structural changes with respect to their presumed activation state. The second target was the H-NOXA domain from a STHK gene in the Nostoc punctiforme PCC 73102 geno (open full item for complete abstract)

Committee: Menachem Shoham PhD (Committee Chair); Focco van den Akker PhD (Advisor); Paul Carey PhD (Committee Member); Irene Lee PhD (Committee Member); Saurav Misra PhD (Committee Member) Subjects: Biochemistry; Biophysics

Master of Science (MS), Wright State University, 2024, Biological Sciences

Excess anthropogenic nitrogen (N), primarily from agricultural field fertilization, causes nutrient runoff that stimulates harmful algal blooms (HABs) in western Lake Erie. As a critical tributary to Lake Erie, nutrient loading from the Maumee River drives the intensity of the annual summer HABs in the western basin. Knowledge gaps around rates of N transformations in the Maumee River currently hinder the calibration of in-river parameters in Soil and Water Assessment Tool (SWAT) models for the Maumee watershed. To address these gaps, this research quantified rates of ammonium uptake, ammonium remineralization, nitrification, and bacterial respiration alongside physicochemical parameters of the river. Monthly sampling was conducted along the Maumee River at International Park (river mile 4.53), Mary Jane Thurston (river mile 31.88), and Independence Dam (river mile 59.31) over the course of a year. Ammonium uptake rates ranged from 1.2 to 8.7 µmol N L-1 hr-1 for water samples incubated under light conditions and from 0.2 to 1.9 µmol N L-1 hr-1 under dark conditions, while ammonium regeneration ranged from <0.01 to 12.0 µmol O2 L-1 hr-1. Bacterial respiration rates averaged 525.0 ± 28.5 µM O2. Respiration and both NH₄⁺ uptake & regeneration rates correlated overall with seasonal temperatures and biomass. Respiration rates closely followed temperature, with warmer months having the highest rates. November 2022 samples exhibited higher rates of respiration and both NH₄⁺ uptake & regeneration at all sites as chlorophyll was >200 µg/L during the fall river bloom. Despite not being at peak temperature in the study, the highest rates of microbial activity in April and May., with the lowest observed during the coldest months, January and March. The timing of peak rates at the three sites along the river-to-lake continuum shifted with biomass, indicating the importance of parameterizing the SWAT model with models with spatially and temporally dynamic values. These findin (open full item for complete abstract)

Committee: Stephen J. Jacquemin Ph.D. (Committee Chair); Silvia E. Newell Ph.D. (Committee Co-Chair); Katie Hossler Ph.D. (Committee Member) Subjects: Biogeochemistry; Environmental Management; Environmental Science; Environmental Studies; Hydrologic Sciences; Hydrology; Water Resource Management

Doctor of Philosophy, The Ohio State University, 2024, Chemical Engineering

Humankind is constantly engaged in the pursuit of innovative approaches to improve process efficiency, economics, and safety. Chemical looping, a novel methodology involving a reaction carried out in multiple stages facilitated by a solid intermediate called a carrier, offers additional degrees of freedom for process intensification and product optimization. This dissertation involves the development and scale-up of new alternatives for several conventional catalytic processes, leveraging the benefits offered by the chemical looping platform to enhance operational flexibility, product yields, and process safety. The first part of this dissertation focuses on the development of alternative processes for the removal of two common industrial pollutants, NOx and H2S. NOx, a harmful pollutant generated during the processing of fossil fuels, is conventionally treated using the Selective Catalytic Reduction (SCR) process, which faces challenges such as high costs and limited operational flexibility. The chemical looping process achieves over 99% NOx removal efficiency, demonstrating significant improvements of 9% and 18% in exergy and effective thermal efficiency, respectively, over the state-of-the-art SCR process. H2S, another harmful pollutant generated during the processing of fossil fuels, is conventionally removed using the Claus Process, which encounters drawbacks such as thermodynamic limitations on conversion and the loss of valuable H2 in the form of H2O. This dissertation introduces a nano-scaled iron sulfide carrier, demonstrating ~70% enhancement in reactivity over traditional bulk carriers in chemical looping H2S splitting into H2 and sulfur. Furthermore, process analyses indicate an improvement of ~22 percentage points in energy and ~8 percentage points in exergy efficiency over the Claus process. The second part of this dissertation involves the development of new processes for commodity chemical production. Formaldehyde, an essential organic chemical wit (open full item for complete abstract)

Committee: Prof. Liang-Shih Fan (Advisor); Prof. Jeffrey Chalmers (Committee Member); Prof. Lisa Hall (Committee Member); Prof. Dawn Anderson-Butcher (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

The growing global energy demand, intensified by industrial development and improved living standards, is exacerbating environmental pollution. Conventional fossil fuel-fired power plants, which are primary sources of electricity, generate substantial quantities of pollutants such as carbon dioxide and nitrogen oxides. A viable solution for generating clean energy and mitigating pollution is chemical looping (CL). Chemical looping is an innovative redox platform that employs solid oxygen carriers to facilitate oxygen transfer between oxidizing and reducing agents. This process prevents their direct contact, thereby eliminating the need for downstream gas purification and resulting in increased cost savings. Moreover, chemical looping technologies inherently improve energy efficiency, consequently reducing entropy generation and exergy loss. In the first part, we investigated a novel approach to NOx purification based on CL principles. This method uses cheaper natural gas as the reductant to effectively eliminate nitrogen oxides instead of NH3. Compared to the traditional selective catalytic reduction (SCR) process, our technique demonstrated an improvement in both exergy efficiency and effective thermal efficiency. The key to this method was employing Nickel Oxide (NiO) as the solid oxygen carrier, which enables the transfer of oxygen from NOx to CH4 without direct contact, thus avoiding environmental issues related to the SCR process such as “Ammonia slip” and catalyst instability. Tests with various oxide-based supports were conducted, with alumina-supported NiO showing superior performance in terms of NOx purification and CH4 regeneration. This NOx purification method was tested in a fixed-bed reactor, displaying optimal reaction kinetics at lower residence times and high CH4 conversion rates, thus proving its potential in mitigating NOx emissions. In the second part of our study, we explored Ca2Fe2O5 as the oxygen carrier for the production of syngas, a cruci (open full item for complete abstract)

Committee: Prof. Liang-Shih Fan (Advisor); Prof. Andre Palmer (Committee Member); Prof. X. Margaret Liu (Committee Member); Prof. Kelley Tilmon (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2022, Arts and Sciences: Chemistry

Reactive oxygen species (ROS) are essential to cellular function but in diseased states elevated levels cause oxidative stress. Skin cancer reported as the most prevalent type of diagnosed cancer in the world is primarily caused by ultraviolet radiation (UVR). Studies show UVR exposure leads to several damaging signaling cascades detrimental to cell survival. One mechanism of damage is the overproduction of ROS through activation of NADPH Oxidase (NOX). NOX is a family of holoenzymes comprised of several subunits required for activations. Upon unique complex assembly, NOX produce ROS such as O2.- ,H2O2, OH- which can cause oxidative damage to lipids, protein, and nucleotides. Recent literature has identified NOX1 activation after UV in skin cells. Thus, NOX1 specific inhibitors are promising candidates for prevention of skin cancers. This research examines the efficacy of novel NOX1 inhibitors designed to decrease damage after UVR exposure. Through disruptions of the binding interaction between NOX1 cytosolic subunit NOXO1 and the membrane bound CYBA peptide these inhibitors are proposed to decrease ROS production by stopping UV induced NOX1 complex activation. Using in vitro based cellular studies in primary keratinocytes inhibitor toxicity and ability to protect cell viability after UV are assessed. Additional studies using an optimized skin explant model demonstrate the ability of inhibitors to decrease cellular stress and UV induced DNA damage. Methods are evaluated for the ability to detect inhibitor modulation of direct ROS species production using glutathione and oxidate burst quantification to detect NOX1 inhibition. These studies in combination with key computation design and biophysical evaluation of CYBA-NOXO1 binding interaction produce several plausible drug candidates for further evaluation as NOX1 specific inhibition.

Committee: Pearl Tsang Ph.D. (Committee Member); Ana Luisa Kadekaro Ph.D. (Committee Member); Peng Zhang Ph.D. (Committee Member); Edward Merino Ph.D. (Committee Member); In-Kwon Kim Ph.D. (Committee Member) Subjects: Chemistry

PhD, University of Cincinnati, 2022, Arts and Sciences: Chemistry

Reactive oxygen species are a group of highly reactive oxygen-containing entities that are important at a cellular level for multiple biological processes. Low concentrations of ROS can be beneficial as powerful signaling molecules in those biological processes, although excessive concentrations can promote high levels of DNA damage and a variety of diseases such as skin cancer. A newly identified intracellular ROS production source in skin cells is NADPH oxidases. Out of the NOX enzyme family, the NOX1 holoenzyme is most abundantly expressed in the human keratinocyte cells. UV radiation can trigger the activation of NOX1 isoforms which stimulate the assembling of member CYBA and the cytoplasmic protein NOXO1. Inhibition of these enzymes represents a catalytic approach toward reducing ROS for the prevention of ROS inducible diseases. Key disease states include melanoma induced by UV exposure. The first half of the dissertation focuses on investigating new small molecule inhibitors of a key NOX1 holoenzyme to address these challenges. We designed a series of molecules by optimizing the structure of diapocynin and evaluated by in-silico docking methods to determine the binding affinity with NOXO1 cytoplasmic protein (1WLP crystal structure). And have synthesized the series of target molecules for the structure-activity relationship studies. In the first section of the project, we discovered that inhibitor NOX_inh_5 was not cytotoxic, but instead improved the viability of human primary cells from UV exposure, decreased the cellular stress in human skin through the p53 pathway, and reduced the UV-induced DNA damage as monitored by quantification of cyclobutane dimer formation after UV exposure. Then, we characterized the inhibition potential of NOX_inh_5 by using an Isothermal calorimetric (ITC) binding assay and heteronuclear single quantum coherence (HSQC) technique and revealed that the candidate molecule can prevent the complex formation of NOXO1 and CYBA me (open full item for complete abstract)

Committee: Edward Merino Ph.D. (Committee Member); Peng Zhang Ph.D. (Committee Member); In-Kwon Kim Ph.D. (Committee Member) Subjects: Pharmaceuticals

MS, University of Cincinnati, 2019, Engineering and Applied Science: Aerospace Engineering

Gas turbine combustors are used to extract chemical energy from the combustion of fuel in presence of an oxidizer to power turbines. Environmental concerns provide motivation to develop more efficient and less polluting gas turbine engines. To achieve good emission performance, lean burn combustors with low pollutant emissions have been developed. These combustors operate at fuel lean conditions and they can be classified into lean premixed and pre-vaporized (LPP) combustor, where the fuel and oxidizer are premixed and pre-vaporized to form a homogeneous mixture in a dedicated region, premixer, just before the fuel-oxidizer mixture enters the combustion chamber, and lean direct injection (LDI) combustor, where the fuel is directly injected into the flame zone without any premixing with oxidizer. The premixing and pre-vaporizing reduce the residence time, the amount of time the gases are in the combustion chamber. The reduction in residence time reduces the NOx emissions, as the high NOx emissions are produced with a long residence time in the combustion chamber. The flow behavior of non-reacting and reacting flow in a lean premixed swirl combustor, adapted from KAUST experimental rig, has been studied using RANS in the commercial software, Ansys - Fluent. Turbulence is modeled using the two equation realizable k-epsilon model and the turbulence - chemistry interaction is modeled by a flamelet generated manifold (FGM) technique with methane-air mixture at an equivalence ratio of 0.67. GRI 3.0 mechanism was used for modeling chemistry, which had 325 chemical equations and 53 species to solve. A central toroidal recirculation zone (CTRZ) was observed from a swirl number, S = 0.52 in the case with a central rod, and from S = 0.54 in the case without a central rod and it helped to stabilize the flame. At low swirl numbers, the central rod, which was in the injection tube, helped the flow and flame to stabilize on top of it. In the absence of this c (open full item for complete abstract)

Committee: Ephraim Gutmark Ph.D. (Committee Chair); Prashant Khare Ph.D. (Committee Member); Rodrigo Villalva Gomez Ph.D. (Committee Member) Subjects: Aerospace Materials

PhD, University of Cincinnati, 2018, Engineering and Applied Science: Aerospace Engineering

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform liquid sheet under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery by using a porous stainless-steel material with 30 µm porosity. The porous tube also acted as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. The current study investigates the aerodynamics, spray quality, fuel-air mixing and emission characteristics of the novel injectors at 4% pressure drop and atmospheric conditions. The injectors have two configurations with different counter-rotating radial-radial swirlers. And the injector 1 has a SN of 0.75 and SN of injector 2 is 0.6. The characteristics of the novel injectors are also compared with a typical airblast injector having a peanut nozzle with flow number of 1. A Central Toroidal Recirculation Zone (CTRZ) and Corner Recirculation Zone (CRZ) are observed from the aerodynamics study. Spray measurements are carried out at various equivalence ratio conditions without a confinement. D10, D32 and D0.5 are investigated on Jet-A, GTL and blended fuels. There is no significant influence of fuel types on the spray behavior due to their similar physics properties. The porous injectors generate a fine spray with weighted SMD ~45 µm at equivalence ratio of 0.6. Gaseous Fuel-air mixing studies are carried out at different equivalence ratios with and without a confinement. A fully premixed mixing profile was obtained at 0.43” downstream of the injector exit. Flame characterization (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Jun Cai Ph.D. (Committee Member); Jongguen Lee Ph.D. (Committee Member); Bassam Mohammad Abdelnabi Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science, University of Toledo, 2018, Civil Engineering

The main objective of this experimental thesis was to present a comprehensive analysis of exhaust emissions from transit buses during daily routine operations. The pollutants monitored in this study are Particulate Matter (PM), NOx, CO2, and HC released from three different buses with different exhaust control systems such as NON-EGR bus, EGR- bus with EGR+DPF+DOC and hybrid bus with EGR+DPF+DOC+SCR. All these buses were tested on the same route each day. To further categorize and elaborate our findings, the runtime was divided into both idle and running conditions. With a specific end goal to accomplish extensive outcomes, the idle condition was additionally divided into two distinct cases, i.e., cold idle and hot idle conditions. The running conditions were also divided into acceleration, deceleration, variable speed, and intersections. The NOx, CO2 and HC emission were gathered and analyzed for every one of the conditions and modes depicted above. The particulate emission was collected and analyzed in idle conditions. In idle condition NOx, CO2 and HC decrease with time and stay constant after they reach 15 minutes of idle time. The cold idle emissions are observed to be very high when compared to the hot idle condition, this is because the hot idle emissions are collected after the bus gets back to the garage from its daily route with a hot engine and this delivers the appropriate amount of fuel into the engine for complete combustion. Whereas cold idle mode does not run at its optimum temperature that leads to incomplete combustion and increases in emission formation. The NOx and HC emissions decreased from NON-EGR to EGR to the hybrid bus because of the emission control systems: SCR, DOC, and EGR, Whereas CO2 emissions, increase by using the same emissions control systems from NON-EGR to EGR to the hybrid bus. The study shows that hybrid bus emits less amount of NOx when compared to EGR and NON- EGR buses, this is because of the exhaust control syste (open full item for complete abstract)

Committee: Ashok Kumar (Committee Chair); Kim Dong Shik (Committee Co-Chair); Hu Liangbo (Committee Member) Subjects: Civil Engineering; Environmental Engineering

PhD, University of Cincinnati, 2018, Engineering and Applied Science: Aerospace Engineering

The goal of this work is to design and develop an injector with a novel porous injection technology (PIT) for dry low NOx combustor (DLN). One of the key factors that is essential for lowering NOx levels is the efficient mixing of fuel-air in both spatial and temporal domains. The porous injection technology has the potential to reduce the spatial and temporal gradients to a minimum. This novel injector design utilized different concepts such as lean premixing, micro-mixing and straight flow with bluff bodies' stabilization mechanism. The micro-mixer is a multi-injector block with nine injectors arranged in an equally spaced rectangular 3 by 3 array. Each injector in the multi-injector block has a porous tube through which fuel is injected. The porous tube is made of stainless steel with 30 µm porosity. Each porous tube is surrounded by eight smaller tubes through which compressed air is passed. The centerbody is mounted above the porous tube. The fuel and air mix in the annular space between the injector wall and the porous tube. The reacting and non-reacting flows of the micro-mixer under atmospheric conditions and a pressure drop of 4% were investigated as part of the injector development process. To evaluate the fuel-air mixing quality, two measurement techniques were used. The CO2 mixing technique - developed in-house, was used to quantify the spatial variations in the fuel mass fraction. Planar Laser Induced Fluorescence (PLIF) was used to obtain both spatial and temporal fuel mass fractions. The CO2 mixing measurements were used to validate the PLIF data for quantification. The RMS fluctuations in spatial and temporal domains were quantified from PLIF data. The length of the upper block was optimized and decided based on the mixing quality. Furthermore, Particle Image Velocimetry (PIV) measurements were conducted to study the injector's aerodynamics under the same operating conditions. The PIV measurements showed a Central Toroidal Recirculation Zone (CT (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Jun Cai Ph.D. (Committee Member); Jongguen Lee Ph.D. (Committee Member); Bassam Mohammad Abdelnabi Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science, University of Toledo, 2016, Civil Engineering

Biodiesel is an alternate to diesel for transit buses due to its environmental benefits. However, NOx and particulate matter emissions may be an issue in the use of biodiesel. The major objective of this experimental thesis was to study tail pipe emissions from transit buses during daily routine operations. This thesis focuses on the trends of NOx and particulate matter emissions collected from buses with EGR and NON-EGR engines during their total run times. To further categorize and elaborate our findings, the run time was divided into both idling and running conditions. In order to achieve comprehensive results, the idling and running conditions were further segregated into two different cases, i.e., cold idling and hot idling conditions. The running conditions were divided into acceleration, deceleration, motion in variable speeds and partial idle modes. The NOx emission values were collected and analyzed for all the conditions and modes described above. The particulate matter emissions were collected and analyzed in idle conditions. It was learned that hotter engines produced lower emissions when compared to cold engine conditions. The experiments and analysis of NOx emissions concluded that maximum emissions were found in the acceleration condition. A Mexa-720 Horiba NOx analyzer was used to measure NOx emissions and Cummins in-site 6 equipment and software program were used for engine data collection during the field study. The experiments were carried out on both transit buses with EGR and NON-EGR engines. The particulate matter emissions collection was carried out with quartz filter papers and a CATCH CAN instrument. An EDS X-Max 50mm2 / FEI Quanta 3D FEG Dual Beam Electron Microscope was used for the EDS analysis of PM emissions and the ICP-MS was carried out using Xseries 2. The transit buses are used by Toledo Area Regional Transit Authority (TARTA). Both the buses were fueled with B5 grade biodiesel without making any engine modifications (open full item for complete abstract)

Committee: Dr. ASHOK KUMAR (Committee Chair); Dr. DONG-SHIK KIM (Committee Co-Chair); Dr. LIANGBO HU (Committee Member) Subjects: Chemical Engineering; Civil Engineering; Environmental Engineering

Doctor of Philosophy, The Ohio State University, 2016, Chemical Engineering

A hydrothermally stable dual-catalyst aftertreatment system for emission control of nitrogen oxides (NOx) with lower hydrocarbons (CHx) has been developed for natural gas-fired stationary lean-burn engines. The dual-catalyst system consists of a physical mixture of a reduction catalyst, palladium supported on sulfated zirconia (Pd/SZ) and an oxidation catalyst, cobalt oxide supported on ceria, CoOx/CeO2. The multifunctional aftertreatment system oxidizes nitric oxide (NO) to nitrogen dioxide (NO2), reduces NO2 to nitrogen (N2), and oxidizes carbon monoxide (CO) and the unutilized hydrocarbons. For practical applications in environmental catalysis, the catalytically active powder catalyst needs to be wash-coated onto a monolith core. To prevent permanent loss of activity due to physical separation of the wash-coat from the walls of the monolith core, adhesivity enhancing materials (binders) are added to the wash-coat. A novel method of incorporating binder to the active catalyst in situ during sol-gel synthesis is presented in this work. Alumina binder incorporated into Pd/SZ in situ during sol-gel synthesis was chosen for further development of a catalytically active washcoat based on activity tests under simulated engine-exhaust conditions. The alumina binder-incorporated Pd/SZ catalyst slurry controlled at pH 1 and calcined at 700oC demonstrated the most promising NOx reduction and CH4 oxidation activity. Cyclic thermal shock tests demonstrated enhanced adhesive properties of the wash-coat to the walls of the cordierite monolith core. Thus, a catalytically active wash-coat with superior adhesive properties was developed for practical application in a real-world aftertreatment unit. The effect of in situ incorporation of alumina to Pd/SZ during sol-gel synthesis on the structural, textural and chemical properties of the resulting catalyst was investigated as these properties significantly influence the catalytic activity of the resulting catalyst. The format (open full item for complete abstract)

Committee: Umit Ozkan PhD (Advisor); Andre Palmer PhD (Committee Member); Kurt Koelling PhD (Committee Member) Subjects: Chemical Engineering

MS, University of Cincinnati, 2016, Engineering and Applied Science: Aerospace Engineering

The present work investigates emission characteristics and flame behavior of a Lean Direct Injection (LDI) combustor at elevated inlet air temperatures and pressures. The LDI consisted of a 9-point fuel injection system setup in a 3 by 3 array, where each point is made of a fuel nozzle fitted into a counter-rotating radial-radial swirler.To optimize flame anchoring and low NOx potential, two swirlers with varying intensities were used. Swirler #1 has a swirl number of 1.03 and is considered the high strength swirler. The larger recirculation zone created by this swirler is desirable for the increased turbulence and residence time, which will allow for more complete combustion and flame anchoring. Swirler #2 has a swirl number of 0.6, and is considered the low strength swirler. The higher axial velocities of this swirler allowed for a decreased residence time, which will lessen NOx production. To balance flame anchoring with lower NOx potential, 3 high strength swirlers were used in the central row of the array and 6 low strength swirlers were placed in the first and third row. To allow for a wide range of operating conditions, three fuel stages were employed with this combustor. The three stages consist of the pilot flame, which is the central cup operating solely, the 5 cup-staged flame, which is the central circuit operating with the 4 side circuit, and the 9 cup-staged flame, which is all active injection points. Three emission probes collected localized combustion byproducts, which were used to measure the molar fractions of nitric oxide, nitrogen dioxide, carbon monoxide, oxygen, and unburned hydrocarbons. Tests were undertaken with inlet air temperatures and pressures varying from 400°F (478-K) to 515°F (541-K) and 1-atm to 7-atm, respectively. Test results indicate that NOx formation is highly dependent on the fuel staging. The emission index of NOx (g-NOx/Kg-Fuel) were similar for just the central circuit lit (pilot) to all circuits lit (9-cup). For exa (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Ahmed M. ElKady Ph.D. (Committee Member); Shaaban Abdallah Ph.D. (Committee Member) Subjects: Aerospace Materials

PhD, University of Cincinnati, 2016, Engineering and Applied Science: Aerospace Engineering

An experimental study was conducted to investigate the effects of the fuel-air mixing on combustion instabilities and NOx emissions in lean premixed combustion. High speed PIV measurements in water were conducted to capture the mean and dynamic behavior of the cold flow generated by a 3X model of the tested premixer. High speed PLIF in water measurements were conducted to quantify the mean and unsteady fuel-air mixing at different momentum flux ratios. Atmospheric combustion tests using the original premixer, were conducted using natural gas and propane at the same momentum flux ratios of the PLIF mixing tests. An emissions analyzer was used to measure the emissions from combustion tests. Dynamic pressure transducers were used to measure the amplitude and the frequency of the dynamic pressure oscillations associated with the combustion instabilities. CHEMKIN-PRO was used to model the atmospheric combustion and predict NOx emissions at different conditions. Results showed that unsteady fuel-air mixing was concentrated at the center and near the outer edges of the premixer. These regions were characterized by high fuel concentration gradients. With the increase in the momentum flux ratio, the concentration gradient and the level of unsteady mixing increased, indicating that the fuel-air spatial unmixedness was the source of the unsteady mixing. It was found that local flow turbulence tended to decrease the concentration gradient through enhancing the fuel-air mixing, which resulted in decreasing the level of unsteady mixing. NOx emissions from atmospheric combustion increased with the increase in the momentum flux ratio due to the increase in the flame temperature and the fuel-air spatial and temporal unmixedness. The intensity of the combustion dynamics increased with the increase in the level of unsteady mixing. Axial injection of the fuel into the regions of strong unsteady mixing eliminated the combustion dynamics through damping the unsteady mixing. Results of CH (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Anne Geraldine Mouis Ph.D. (Committee Member); Awatef Hamed Ph.D. (Committee Member); Samir Tambe Ph.D. (Committee Member) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 2015, Chemistry

This dissertation focuses on three projects involving the development of harsh environment gas sensors. The first project discusses the development of a multipurpose oxygen sensor electrode for use in sealing with the common electrolyte yttria stabilized zirconia. The purpose of the sealing function is to produce an internal reference environment maintained by a metal/metal oxide mixture, a criteria for miniaturization of potentiometric oxygen sensing technology. This sensor measures a potential between the internal reference and a sensing environment. The second project discusses the miniaturization of an oxygen sensor and the fabrication of a more generalized electrochemical sensing platform. The third project discusses the discovery of a new mechanism in the electrochemical sensing of ammonia through molecular recognition and the utilization of a sensor taking advantage of the new mechanism. An initial study involving the development of a microwave synthesized La0.8Sr0.2Al0.9Mn0.1O3 sensor electrode material illustrates the ability of the material developed to meet ionic and electronic conducting requirements for effective and Nernstian oxygen sensing. In addition the material deforms plastically under hot isostatic pressing conditions in a similar temperature and pressure regime with yttria stabilized zirconia to produce a seal and survive temperatures up to 1350 oC. In the second project we show novel methods to seal an oxygen environment inside a device cavity to produce an electrochemical sensor body using room temperature plasma-activated bonding and low temperature and pressure assisted plasma-activated bonding with silicon bodies, both in a clean room environment. The evolution from isostatic hot pressing methods towards room temperature complementary metal oxide semiconductor (CMOS) compatible technologies using single crystal silicon substrates in the clean room allows the sealing of devices on a much larger scale. Through this evolution in bonding te (open full item for complete abstract)

Committee: Prabir Dutta (Advisor) Subjects: Chemistry; Materials Science

MS, University of Cincinnati, 2015, Engineering and Applied Science: Aerospace Engineering

Current trends with swirler/combustor designs tend towards lower emissions in accordance with ICAO standards, with the main problems inherent in common lean-direct-injection (LDI) designs being poor stability and autoignition or flashback issues. The LDI design is meant to combine the good stability and performance of a traditional rich-burn quick-quench lean-burn (RQL) combustor with the ultra-low NOx emissions of a lean-premixed-prevaporized (LPP) combustor. The goal of this research is to investigate the feasibility of using swirlers with varying swirl strengths in an LDI combustor array by performing a series of combustion tests at atmospheric pressure. Three configurations were designed and tested which contained different arrangements of two counter-rotating radial-radial swirler designs with varying swirl strengths in a 3x3 array format. All nine swirlers contained a fuel nozzle with very similar flow numbers and were all set to the same insertion depth with respect to the swirlers' flare exits. Two nozzle insertion depths were investigated to see how the performance changes with changing insertion depth. Three fuel circuits supplied fuel to the nine fuel nozzles to the center, sides, and diagonal swirlers respectively. Testing was conducted by placing the hardware on a horizontally-oriented test rig connected to an air intake manifold, with the inlet air preheated to approximately 400°F and the pressure drop across the swirler set to 4% of atmospheric pressure. These tests investigated fuel staging configurations at various simulated engine throttle settings and flight conditions to gauge the steady-state combustion and LBO characteristics and low- NOx potential of this design. The results of this testing show that all three configurations tested were able to achieve stable-burning with low equivalence ratios for the three simulated flight conditions tested, as well as across a number of other investigated parameters. The two high-strength swirler conf (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Shaaban Abdallah Ph.D. (Committee Member); Jongguen Lee Ph.D. (Committee Member) Subjects: Aerospace Materials

MS, University of Cincinnati, 2014, Engineering and Applied Science: Aerospace Engineering

The focus of this research is to investigate the isothermal aerodynamic behavior of three LDI configurations utilizing a 3 x 3 array of radial-radial swirlers. Configurations consisted of varying combinations of two swirlers featuring high and low swirl intensity. Two-dimensional velocity data is presented from the measurement of 37 planes spanning the width of the LDI array. An experimental aerodynamic investigation has been carried out on a preliminary Lean Direct Injection (LDI) combustor to discern the effects on the flow-field resulting from interactions between low and high-swirl counter-rotating radial-radial air swirlers in a 9-swirler array. Particle Image Velocimetry (PIV) was used to take velocity field measurements and to study the inter-swirler interactions. The goal of this work is to improve upon the stability limits of current LDI designs while maintaining the current emissions capabilities established by existing LDI designs. The test setup consisted of 9 swirlers arranged in a 3 x 3 pattern with a spacing of 1 inch between the swirler centers. A square plexiglass chamber with an inner dimension of 4.5 x 4.5 inch was used for flow field confinement. A high-speed PIV system was used to take 2D velocity measurement in a vertical plane parallel to the swirler axes. Measurements were conducted at a total of 37 planes spanning the width of the enclosure in an attempt to completely describe the flow field. Three test cases were studied which utilized a combination of a low and high Swirl Number swirlers: the baseline case utilized 9 low swirl (SN about 0.6) swirlers, the second case used one high swirl (SN about 1.0) swirler in the center of the array, and the third case used 3 high swirl swirlers in a row within the array. The flow field developed by the three experimental cases differed significantly and inter-swirler interaction proved significant and highly complex. The velocity fields developed from swirlers in an array varied from that of th (open full item for complete abstract)

Committee: San-Mou Jeng Ph.D. (Committee Chair); Jongguen Lee Ph.D. (Committee Member); Samir Tambe Ph.D. (Committee Member) Subjects: Aerospace Materials