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Polycyclic aromatic hydrocarbons (PAHs) have been heralded as mutagenic and carcinogenic substances and currently, their emissions are subject to regulatory control due to recently imposed stricter environmental regulations. Hence, it has become necessary to have a detailed understanding of their chemistry. In this work, a short review of the available PAH relevant counterflow diffusion flame datasets is presented. Following that, the reliability of four widely used PAH mechanisms and the revised PAH mechanism, within the scope of this work, is assessed by validating them against these collected experimental datasets. The formation of the first aromatic ring is investigated based on the performed reaction path analyses. The results show that the dominant reaction pathways for the formation of benzene are “even carbon atom” pathways (H-abstraction acetylene addition) and “odd carbon atom” pathways (recombination of propargyl radicals). The dominance of one pathway over the other was found to be strongly dependent on the fuel structure and its doping with other components.

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2019; Aachen 1 Online-Ressource (xx, 135 Seiten) : Illustrationen, Diagramme (2019). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2019, Fuel components derived from non-edible biomass are regarded as sustainable substituents for conventional fuels. A major prerequisite for their application in engines, however, is the understanding of their detailed oxidation behavior, which strongly depends on the fuel structure. In the present work, the oxidation behavior of a group of bio-derived furans and tetrahydrofurans is investigated by developing their detailed chemical kinetic mechanisms. Furthermore, to identify potential fuel blends for the desired applications, a systematic optimization approach is proposed. The first part of this thesis is a detailed investigation of the effect of blending an octane booster, 2-methylfuran, with the more reactive primary reference fuel candidate, n-heptane. A detailed model comprising the chemistry relevant for 2-methylfuran and n-heptane was formulated, which predicts newly measured and literature data well. A non-linear mixing behavior was observed, and the detailed chemical analysis reveals no direct interaction between these two fuels, but the effect of 2-methylfuran as a radical scavenger is responsible for this trend. The second part of the thesis addresses the question, how a small change in molecular structure can lead to a substantial change in the reactivity. The oxidation behavior of two structural isomers, 2-methyltetrahydrofuran and 3-methyltetrahydrofuran, is investigated numerically and experimentally. The developed detailed chemical kinetic models show good agreement with experimental ignition delay measurements and flame data from the literature. The influence of molecular structure on ignition propensity was investigated by comparing the ignition delay times of these two components. A comparative reaction path analysis ensures that the location of the side chain is the decisive factor for their ignition propensity. The last part of the thesis focuses on the optimization of potential gasoline blending agents. For this purpose, a large database containing the physical and chemical properties of about 500 fuel components was established. In order to identify the potential candidates, a simple automatic tool was developed, whose main functions involve the physicochemical property calculation of the blends based on pre-defined blending rules and selecting the potential candidates for a set of constraints on these properties. Fuel candidates comprising the alcohol and ketone functional groups were observed to have good potential for blending with gasoline for superior efficiency., Published by Aachen