A surrogate mixture and kinetic mechanism for emulating the evaporation and autoignition characteristics of gasoline fuel (original) (raw)

2015, Combustion and Flame

Gasoline direct-injection spark-ignition engines and gasoline direct-injection compression-ignition engines have received attention due to their higher fuel economy with respect to conventional port fuel injected internal combustion spark-ignition engines. Combustion modeling of these types of engines requires a fuel surrogate that mimics both physical (e.g., evaporation) and chemical (e.g., combustion) characteristics of the gasoline fuel. In this work, we propose a novel methodology for the formulation of a gasoline surrogate based on the essential physical and chemical properties of the target gasoline fuel. Using the proposed procedure, a surrogate with seven components has been identified to emulate the physical and chemical characteristics of a real non-oxygenated gasoline fuel, RD387. A surrogate kinetic mechanism was developed by combining available detailed kinetic mechanisms from the Lawrence Livermore National Laboratory library. The modeling results for distillation curve, ignition delay and laminar flame speed were validated against available experimental data in the literature. The surrogate and gasoline fuels display similar physical/chemical properties, including distillation curve, H/C ratio, density, heating value, and ignition behavior and flame propagation over a wide range of pressures, temperatures, and equivalence ratios. (O.S. Abianeh). distillation curves and evaporation behaviors of these components and their mixtures are different from gasoline as discussed later. On the other hand, suggested representatives for modeling gasoline distillation or evaporation behavior are n-pentane, n-heptane, and n-decane (e.g., ). However, mixtures of these components cannot emulate the ignition delays and laminar flame speeds of gasoline adequately. The question of the present work is: can a single mixture be formulated that will mimic both the evaporation and combustion characteristics of the target gasoline? Towards that goal, a surrogate that includes most of the hydrocarbon group representatives found in a non-oxygenated gasoline is developed here to emulate the combustion and evaporation behaviors of this target gasoline. The surrogate contains n-alkane, iso-alkane, aromatic, and olefin representatives and a detailed kinetic mechanism is built from literature mechanisms for each of the species. The surrogate components and mixture composition are defined via a methodology that seeks a surrogate formulated from a minimum number of species that have relatively well defined kinetic mechanisms and provides adequate emulation of real gasoline evaporation and ignition behaviors.