Light intensity distribution studies in the heterogeneous photocatalytic reactors were carried out successfully with potassium ferrioxalate chemical actinometry, reproducible light intensity estimates of the irradiation source were obtained. The increased light intensity in the reactor system increased the absorption as determined by actinometry. It was found that reflectivity was a dependent variable but mesh opening area was an independent variable. The photocatalytic mineralization of dichoroacetic acid DCAA, in the presence of TiO2 immobilized on a plate in an externally irradiated bubble column photoreactor had been investigated. The mass transfer and activity evaluation were measured. It was found that increasing the catalyst thickness, increased the photoactivity until it reaches the optimum loading, further loading increase caused the reaction rate to remain constant. This phenomenon was observed with increased lamp power (intensity) and initial solute concentration. However, the catalyst activity was not influenced by the increasing concentration of dissolved oxygen. The reaction rate for DCAA photomineralization was expressed using the Langmuir-Hinsheldwood model.

The goals of this research were first to examine flame quenching in tubing smaller than the quench diameter, and then to place lower size limits on microcombustor and microreactor systems by studying a catalytic microcombustor burning propane. In the first set of experiments, flame quenching was examined as a function of wall temperature for various hydrocarbon fuels. This was accomplished by creating a wall temperature profile along a tube, allowing a flame to propagate down the tube, and measuring the temperature of the tube wall coincident with the flame front. This wall quench temperature was plotted as a function of both the equivalence ratio and tube diameter. Fuels tested included propane, hexane, kerosene and diesel. Results showed that quench diameter was reduced by elevating the wall temperature and that the quench temperature increased for increasing mixture flow velocities. Flames were produced in tubes down to 0.8 mm in diameter. In the second set of experiments, a catalyst was used in combination with fuel preheating to obtain a self-sustaining combustion reaction in a chamber approximately 0.25 mm³ in size. Propane was used in this experiment. Results demonstrated that a stable self-sustaining reaction can be obtained in the microscale regime and that reaction temperatures are on the order of 900°C. This research not only aided in the characterization of hydrocarbon combustion in small diameter channels but also showed promise for development of microcombustor systems. / Graduation date: 2002

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references.

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State of the art aircraft afterburners employ spray bars to inject fuel and flameholders to stabilize the combustion process. Such afterburner designs significantly increase the length (and thus weight), pressure losses, and observability of the engine. This thesis presents a feasibility study of a compact prime and trigger (PAT) afterburner concept that eliminates the fuel spray bars and flameholders and, thus, eliminates the above-mentioned problems. In this concept, afterburner fuel is injected just upstream or in between the turbine stages. Downstream of the turbine stages, a low power pilot, or trigger , can be used to control the combustion process. The envisioned trigger for the PAT concept is a jet of product gas from ultra-rich hydrocarbon/air combustion that is injected through the afterburner liner. This partial oxidation (POx) gas, which consists mostly of H2, CO, and diluents, rapidly produces radicals and heat that accelerate the autoignition of the primed mixture and, thus, provide an anchor point for the afterburner combustion process. The objective of this research was to demonstrate the feasibility of the PAT concept by showing that (1) combustion of fuel injected within or upstream of turbine stages can occur only downstream of the turbine stages, and (2) the combustion zone is compact, stable and efficient. This was accomplished using two experimental facilities, a developed theoretical model, and Chemkin simulations. The first facility, termed the Afterburner Facility (AF), simulated the bulk flow temperature, velocity and O2 content through a turbojet combustor, turbine stage and afterburner. The second facility, termed the Propane Autoignition Combustor (PAC), was essentially a scaled-down, simplified version of the AF. The developed model was used to predict and interpret the AF results and to study the feasibility of the PAT concept at pressures outside the AF operating range. Finally, the Chemkin simulations were used to study the effect of several POx gas compositions on the afterburner combustion process.

Light intensity distribution studies in the heterogeneous photocatalytic reactors were carried out successfully with potassium ferrioxalate chemical actinometry, reproducible light intensity estimates of the irradiation source were obtained. The increased light intensity in the reactor system increased the absorption as determined by actinometry. It was found that reflectivity was a dependent variable but mesh opening area was an independent variable. The photocatalytic mineralization of dichoroacetic acid DCAA, in the presence of TiO2 immobilized on a plate in an externally irradiated bubble column photoreactor had been investigated. The mass transfer and activity evaluation were measured. It was found that increasing the catalyst thickness, increased the photoactivity until it reaches the optimum loading, further loading increase caused the reaction rate to remain constant. This phenomenon was observed with increased lamp power (intensity) and initial solute concentration. However, the catalyst activity was not influenced by the increasing concentration of dissolved oxygen. The reaction rate for DCAA photomineralization was expressed using the Langmuir-Hinsheldwood model.

[11] 212 leaves : ill., plates ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1974) from the Dept. of Physics, University of Adelaide

Thesis (Ph.D.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2008/01/11). Includes bibliographical references.