Development of high-pressure rate rules for alkyl + O2 reactions

Abstract

The need for increased engine performance / efficiency and new alternative fuels has proven kinetic modeling studies to be a valuable tool to assess new fuels and find optimal operating conditions. Research is geared toward verifying rate constants in key reaction pathways for low temperature hydrocarbon oxidation mechanisms. Obstacles to overcome are: the thousands of species involved in each combustion, the tens-of-thousands of reaction pathways available, the limited experimental data available and high-level calculations restricted to small molecules. The strategy was to use abinitio computational methods to calculate rate constants for smaller species, and then generalize the results on a per-site basis for larger species. Results suggest that the direct use of HP rate rules is sufficient to describe reactions under most conditions relevant to combustion/ignition engine problems. Future research efforts are directed toward refining data by improving thermodynamic profiles for reactants and transition states.