A better understanding and control of internal combustion engine pollutants require more insightful investigation of gasoline oxidation chemistry. An oxidation study has been done on n-heptane, iso-octane, their binary mixtures (Primary Reference Fuel, (PRF)), and nine hydrocarbon mixtures which represent the second generation of gasoline surrogates (multi-component surrogates). This study aims to develop a better understanding of the combustion reaction by studying the oxidation reaction of different fuels inside a jet-stirred reactor and numerically simulating the reaction using different models under the following conditions: pressure 1 bar, temperature 500-1050K, residence time 1.0 and 2.0s, and two fuel-to-oxygen ratios (ϕ=0.5 and 1.0). Intermediate and product species mole fractions versus temperature profiles were experimentally measured using a GC (gas chromatograph). The experiment was performed within the high and low-temperature regions, where the high-temperature oxidation showed similar behavior for different compositions but the low-temperature oxidation showed significant dependence on the composition of the surrogates. Additionally, the effect of octane number on oxidation chemistry has been investigated and it was found that the low octane number surrogates were more reactive than high octane number surrogates during the low temperature regime. Furthermore, Kinetic analysis was conducted to provide insightful understanding of different factors of fuel reactivity. In addition, the pyrolysis of two TPRF, (Toluene primary reference fuels) mixtures (TPRF70 and TPRF97.5), representing low octane (research octane number 70) and high octane (research octane number 97.5) gasoline, was also studied in jet-stirred reactor coupled with gas chromatography (GC) analysis to investigate the formation of soot and polycyclic aromatic hydrocarbons (PAH) formation.

Gasoline compression ignition (GCI) engines show promise in meeting stringent new environmental regulations, as they are characterized by high efficiency and low emissions. Simulations using chemical kinetic models provide an important platform for investigating the behaviors of the fuels inside these engines. However, because real fuels are complex, simulations require surrogate mixtures of small numbers of species that can replicate the properties of real fuels. Accordingly, the development of high fidelity, well-validated kinetic models for surrogates is critical in order to accurately replicate the combustion chemistry of different fuels under engine-related conditions. This work focuses on the development of combustion kinetic models to better understand gasoline fuel combustion in GCI engines. An updated iso-octane detailed kinetic model was developed based on new thermodynamic group values and recently evaluated rate coefficients from literature. The model was validated against a wide range of experimental data and conditions. The iso-octane model was further used in 0D simulations for a homogeneous charge compression ignition (HCCI) engine. The results showed that the low-temperature heat release in engines increases with engine boosting when the addition of alky radicals to molecular oxygen is more favored. Ethanol addition was also found to act as a radical sink which inhibits the radical pool formation and results in lower reactivity. Although detailed models provide clarification of the combustion chemistry, their high computational cost impedes their utilization in 3-D engine simulations. Hence, a reduced model for toluene primary reference fuels was developed and validated against ignition delay time and flame speed experiments from literature. The model was then used in numerically investigating the effects of the fuel’s physical properties using hollow-cone and multi-hole injectors in a partially premixed compression ignition (PPCI) engine. It was concluded that the effects of physical properties are evident in multi-hole injection cases, which is attributable to the differences in mixture stratification. Finally, reduced models for multi-components surrogates for three full-blend fuels (light naphtha-Haltermann straight-run naphtha and GCI fuels) were developed. The models were validated against ignition delay time experiments from the literature and tested in 3D engine simulations.