Development of Support Tools for Next-generation Combustion Engineering using Reaction Knowledgebase

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The detailed kinetic modeling has been claimed to be indispensable for development of next-generation combustion technology, such as homogeneous charge compression ignition. In this study, a tool for combustion engineering, which automatically generates the detailed model for the mixture of any saturated hydrocarbons, has been developed.Detailed models, including thousands to tens of thousands elementary reactions, are beyond the reach of a simple database approach, and can only be achieved by a well-structured knowledgebase of empirical rules based on the knowledge on the similar reactions. The knowledge has been acquired from the previous and present experimental results as well as the results of quantum chemical calculations performed in this study. The quantum chemical calculations were inevitable, particularly for the competition of isomerization and dissociation processes of alkylperoxy radicals, which play essential role in the ignition.The auto-generation tool developed has bee … More n validated as follows :1)First, the models generated by the tool were confirmed to reproduce the ignition delay time for n-heptane and iso-octane, the primary reference fuels for the octane number.2)Second, it was necessary to validate that the models for fuels of various kinds and structures reproduce the trends of the ignition properties. This was done by calculating the critical compression ratio for the zero-dimensional ignition for 50 alkanes, for which the experimental RONs (research octane numbers) have been reported. A good correlation was found between RONs and critical compression ratios calculated by the detailed kinetic models generated by the tool developed in the present study.These results indicate that the models generated in the present study can reproduce the trends of auto-ignition, at least semi-quantitatively for many hydrocarbons. Also several new features have been found in the ignition properties of individual fuel molecules, which cannot be described by the existing rating such as RON. Less