From elementary reactions to evaluated chemical mechanisms for combustion models

Methods of determining rate data for elementary reactions for combustion applications, using experimental and theoretical methods, are briefly reviewed. The approaches are illustrated by reference to recent research in three areas: (i) reactions of OH with C2H4 and C2H2, where theory, tuned by reference to experiment, has provided a substantial contribution to the determination of rate data for these complex reactions, over a wide range of temperatures; (ii) reactions between alkyl radicals and O2, where theory and experiment have been closely allied in discerning the details of mechanisms for small alkyl radicals; much remains to be done with larger radicals; (iii) reactions of methylene and the interactions between chemical reaction and the conversion of the singlet state into the triplet, where theory has played little part thus far. Comments are also made on the process of evaluating rate data for elementary reactions for incorporation in chemical mechanisms for use in combustion models.