Kinetic investigations of gaseous fuels through ignition delay time and species mole fraction measurements at high pressures

Combustion engines are still a viable mode for energy production, transportation of people and commodities. Increasing efficiency, reducing emissions, and simultaneously making a cost-effective end product has remained the priority in the research performed in these sectors. The understanding of fundamental physico-chemical parameters is associated with improving efficiency and reducing emissions in combustion engines. The combustion of conventional fuels and potential alternate fuels are investigated from a fundamental perspective to obtain insights into their oxidation pathways and the harmful species formed during the process. These investigations are performed for a wide range of application relevant conditions to gain a comprehensive insight into fuel oxidation. The focus of this thesis is to establish experimental techniques to explore the oxidation of gaseous fuels at elevated pressures. In this aspect, the rapid compression machine is employed to obtain ignition delay time measurements in the pressure range from 20 bar to 160 bar, where pressures above 50 bar are not often investigated in the literature due to limitations in the experimental facilities. Secondly, a method for extracting gas samples from the reactor during the ignition delay period in the rapid compression machine is developed in this work. The extracted samples are analyzed using gas chromatography and mass spectrometry techniques to obtain information on stable intermediate species formed during fuel oxidation. Gas sampling techniques have often been used in the literature but have been limited to lower pressures and diluted conditions. In this thesis, an approach to obtain stable intermediate species mole fraction profiles at higher pressures and non-diluted conditions is established. Additionally, the possibility of transferring the sampling technique established in the rapid compression machine to the shock tube is investigated. Throughout the thesis, the approach to the measurements at the different conditions is explained in detail, along with the experimental uncertainties. Finally, all the experimental data obtained through these measurement techniques have been utilized to develop, optimize, and attain a consistent, detailed chemical kinetic mechanism, NUIGMech1.0. The developed mechanism is utilized to perform sensitivity and reaction pathway analysis to comprehend the pathways that control the reactivity of the fuel. As part of this thesis, neat components of methane, ethane, propane, propene, their mixtures, automotive LPG fuels, and propylene oxide have been investigated