The kinetics of the reaction of atomic sulfur with acetylene (S (3P) + C2H2) were investigated experimentally via the flash photolysis resonance fluorescence method, and the theoretical potential energy surface for the reaction CN + SO was modeled via the density functional and configuration interaction computational methods. Sulfur is of interest in modern chemistry due to its relevance in combustion and atmospheric chemistry, in the Claus process, in soot and diamond-film formation and in astrochemistry. Experimental conditions ranged from 295 – 1015 K and 10 – 400 Torr of argon. Pressure-dependence was shown at all experimental temperatures. The room temperature high-pressure limit second order rate constant was (2.10 ± 0.08) × 10-13 cm3 molecule-1 s-1. The Arrhenius plot of the high-pressure limit rate constants gave an Ea of (11.34 ± 0.03) kJ mol-1 and a pre-exponential factor of (2.14 ± 0.19) × 10-11 cm3 molecule-1 s-1. S (3P) + C2H2 is likely an adduct forming reaction due to pressure-dependence (also supported by a statistical mechanics analysis) which involves intersystem crossing. The potential energy surface for CN + SO was calculated at the B3LYP/6-311G(d) level and refined at the QCISD/6-311G(d) level. The PES was compared to that of the analogous reaction CN + O2. Notable energetically favorable products are NCS + O, CO + NS, and CS + NO. The completed PES will ultimately be modeled at the CCSD(T) level (extrapolated to infinite basis set limit) for theoretical reaction rate analysis (RRKM).

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A Thesis Presen ted in Fulfilm ent of the Requirem ents for the Degree of Doctor of Philosophy in Engineering August 1963 / The objectives of combustion research are considered and attention directed to laminar flames, the burning velocity of which is recognised as a basic parameter in all combustion problem s. Various methods of determining this property are critically reviewed and, as a result, it is concluded th at the spherical constant volume vessel technique is potentially one of the most versa tile and accurate. However this method does not appear to have been extensively used, probably because the available equations virtually relegate it to the status of a constant pressure technique

The goal of this study is to investigate how varying the configuration of an axially staged combustion test facility affects the resultant flame and its relevant characteristics. Such relevant characteristics are the jet liftoff and the centerline jet trajectory. The configurations that are primarily being investigated are varied jet configuration diameters, 4mm and 12.7mm, preheated and non-preheated fuel, and different fuels. The testing facility is located at the University of Central Florida in the PERL (Propulsion and Energy Research Lab) facility. The facility allows for modeling an industrial turbine combustor, specifically an axial staged combustor with a Jet-In-Crossflow enabled second stage. It also allows for pressurizing the entire facility which keeps the studies performed on the facility consistent with industrial conditions. The facility is running off pressurized methane and air. The tests were ran with constant equivalence ratios and momentum flux ratios while varying the above configurations to capture how the relevant characteristics were changed.

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<p> Measurement of cellular carbon has been accomplished by gravimetric, titrimetric or directly measuring CO₂ produced in the combustion of organic carbon in the Carbon Analyzer Gravimetric and titrimetric methods are cumbersome, inaccurate at concentrations higher than 600mg/l. </p> <p> The purpose of this series of experiments is to find an alternative method for measuring cellular carbon. The proposed method is based in a carbon balance in which the soluble and gaseous forms of carbon are monitored. Cellular carbon is calculated by subtracting the sum of the soluble and gaseous forms of carbon from the initial total carbon found in the reactor. </p> / Thesis / Master of Engineering (MEngr)

This thesis investigates the exposure of humans to organic combustion products. Combustion of natural and anthropogenic materials can lead to highly complex mixtures of gas-phase and particle-bound chemical compounds, whose composition and health effects have been studied extensively. Nevertheless, the analysis of other potentially toxic products remains a challenge due to lack of analytical standards and methodologies. The research that encompasses this thesis is a progression from the analysis of known combustion products to the identification of previously unknown products. Targeted analytical techniques, such as gas chromatography tandem mass spectrometry (GC-MS/MS), were utilized to evaluate firefighter exposure to wood smoke chemicals during training exercises. The results suggest that a subset of the firefighters were at higher risk of exposure which could be related to specific operational roles and the use of personal protective gear. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCGC-TOF) was used for the identification of novel wood smoke markers and the results indicate that firefighters are equally exposed to gas-phase and particle phase compounds.. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry is a non-targeted technique that is complementary to GCGC. Together, these tools enabled the identification of a suite of halogenated PAHs (haloPAHs) in samples obtained from the Plastimet Inc. fire, one the largest industrial fires in North America. HaloPAHs are similar in structure to toxic polychlorinated dibenzo-p-dioxins (PCDDs), a notorious class iv of toxic chemicals, and they were detected at much higher concentrations. In addition, highly substituted and high molecular weight haloPAHs were detected for the first time in an environmental sample. Finally, negative ion atmospheric pressure chemical ionization (NI-APCI) was explored as an alternative ionization technique for the analysis of mixed bromo/chloro dioxins (PXDDs) in the ash sample. PXDDs, with 1550 possible congeners, are potentially more toxic than their chlorinated counterparts (PCDDs). NI-APCI derived structure diagnostic fragments enabled the differentiation of co-eluting PXDD isomers in the ash sample which has not been possible using traditional ionization techniques (EI/CI) associated with GC-MS. / Thesis / Doctor of Philosophy (PhD)

Plasmas when coupled to the oxidation process of various fuels have been shown to influence the process positively by improving upon flameholding, reduction in ignition delay time, reduced pollutant emission, etc. Despite all this positive effects being known to the science community, the mechanisms through which the plasmas effects all these enhancements are poorly understood. This is often due to the absence of accurate experimental data to validate theoretical mechanisms and the availability of a myriad sources of plasmas having different chemistries. The goal of this thesis is to further narrow the knowledge gap in the understanding of plasma assisted combustion by using a nonthermal microwave plasma to investigate the mechanism through which it enhances the oxidation of several fuel/oxidant combinations. The enhancement metrics used in this studies are minimum ignition energy, flameholding and rotational temperature. A suite of noninvasive optical diagnostics techniques (camera for visual imaging, optical emission spectroscopy and cavity ringdown spectroscopy) are employed to probe the plasma assisted combustion flame and identify the species, obtain rotational temperatures, and identify pathways through which the microwave plasma enhances the combustion process. Initially, the effect of a microwave plasma on the ignition and flameholding of an ethylene/air mixture was investigated. Then, based on observations from that study and previous studies, a novel plasma assisted combustion platform was designed capable of discriminating between the various pathways through which the plasma enhances the combustion of a fuel/air mixture. Using the designed platform, a comparative study was carried out on the roles played by the plasma activated fuel vs. plasma activated oxidizer stream. The roles played by the plasma activated fuel or air molecules in the ignition of the fuel/air mixture was investigated. Data from this study led to the suggestion that there exist a minimum required plasma generated radical pool for ignition to occur with reactive oxygen and nitrogen playing a more important role in the ignition and flameholding effects. Ground state OH(X) number densities were also measured for the first time in the hybrid ignition zone of a plasma assisted combustion reactor using cavity ringdown spectroscopy.

A zero dimensional single zone model was developed to determine the crank resoled heat release rate at various injection timings (15°-60° BTDC) and the associated uncertainties from a pilot ignited natural gas engine. The uncertainty analysis examines the percentage contribution from various sources of error, including cylinder pressure measurements, intake manifold pressure measurements, and the impact of assumptions such as constant versus temperature dependent specific heat ratios. In particular, uncertainty percentage contributions and uncertainty magnification factors were used to quantify and compare the uncertainties in heat release rates using temperature dependent specific heat ratio correlations to constant specific heat ratio assumption. It is demonstrated that the error associated with the constant specific heat ratio assumption contributes to about 40 percent error (full scale value) in the net heat release estimates in comparison to using temperature dependent specific heat ratio correlations.