Bingjie Chen, Ph.D. student, supervised by Prof. Mani Sarathy presented his Ph.D. dissertation titled 'Gasoline combustion chemistry in jet stirred reactor' on 12 March, 2019. He joined CCRC, KAUST in the year 2014 as a Ph.D. student and has been researching with the Combustion and Pyrolysis Chemistry (CPC) Group supervised by Prof. Mani Sarathy. His research interests are in the areas of laser diagnostics in combustion system.
Pollutants control and efficiency improvement drive the need for clean combustion research on internal combustion engines. To design cleaner fuels for advanced combustion engines, gasoline combustion chemistry needs to be understood and developed. A comprehensive study on gasoline combustion chemistry in jet stirred reactor is presented in this dissertation.
Real gasoline fuels have thousands of hydrocarbon components. This makes numerical simulations difficult. To mimic real gasoline fuel behaviors, surrogates composed of a few hydrocarbon components are proposed as a viable approach. In this dissertation, combustion chemistry of n-heptane, a key and sensitive surrogate component, is investigated first. Performance of surrogate kinetic model is evaluated next. Finally, real gasoline fuels are examined with the proposed surrogate kinetic model.
To study n-heptane combustion chemistry, mass spectrometry was employed to identify and quantify intermediates in n-heptane low temperature chemistry. Reaction pathways of observed intermediates were proposed and elucidated. n-Heptane low temperature oxidation reaction scheme is validated and widen by the proposed reactions, which is crucial for spark ignition during the cold start of the engines.
Surrogate kinetic model is examined next after surrogate proposal and formation. Low temperature oxidation chemistry and high temperature combustion chemistry were observed and predicted. Octane number and composition effect were revealed on low temperature oxidation reactivity. Key reactions were highlighted and reviewed. High temperature combustion chemistry was found similar among different surrogates. The surrogate kinetic model can well reproduce surrogates behaviors in both low and high temperature with experimental validations. Finally, the proposed surrogate model was examined with real gasoline fuels. To represent thousands of gasoline fuels, five real FACE (Fuel for Advanced Combustion Engines) gasolines were selected as target fuels to cover a wide range of octane number, octane sensitivity and hydrocarbon compositions.
Low temperature oxidation chemistry was investigated for two intermediate octane number gasolines, FACE A and C. For a high octane number gasoline, FACE F, key pollutant production pathways were highlighted in high temperature combustion chemistry. Two low octane number gasolines, FACE I and J, are compared with other three FACE gasolines to examine surrogate model and elucidate gasoline combustion chemistry over a wide range. Gasoline surrogate chemical kinetic model was proven to be a comprehensive, viable, accurate and powerful approach for numerical simulations validated by comprehensive experimental data. Proposed gasoline surrogate chemical kinetic model can help with numerical design on advanced combustion engines.