A COMPREHENSIVE MODELING STUDY OF N-HEPTANE OXIDATION

A detailed chemical kinetic mechanism has been developed and used to s tudy the oxidation of n-heptane in flow reactors, shock tubes, and rap id compression machines. Over the series of experiments numerically in vestigated, the initial pressure ranged from 1-42 atm, the temperature from 550-1700 K, the equivalence ratio from 0.3-1.5, and nitrogen-arg on dilution from 70-99%. The combination of ignition delay time and sp ecies composition data provide for a stringent test of the chemical ki netic mechanism. The reactions are classed into various types, and the reaction rate constants are given together with an explanation of how the rate constants were obtained. Experimental results from the liter ature of ignition behind reflected shock waves and in a rapid compress ion machine were used to develop and validate the reaction mechanism a t both low and high temperatures. Additionally, species composition da ta from a variable pressure now reactor and a jet-stirred reactor were used to help complement and refine the low-temperature portions of th e reaction mechanism. A sensitivity analysis was performed for each of the combustion environments. This analysis showed that the low-temper ature chemistry is very sensitive to the formation of stable olefin sp ecies from hydroperoxy-alkyl radicals and to the chain-branching steps involving ketohydroperoxide molecules. (C) 1998 by The Combustion Ins titute.