On the Derivation of Global Ignition Kinetics from a Detailed Mechanism for Simple Hydrocarbon Oxidation

Abstract

A method for deriving global ignition kinetics from a detailed chemical mechanism is described, with the lime-temperature range of applicability assessed. The computed ordering of simple hydrocarbons by ignition temperature is consistent with published data. Values of the global rate parameters were found to be only weakly dependent on gas mixing intensity, as determined by a comparison of results from a perfectly-stirred reactor model and plug flow reactor model. Major reaction pathways prior to and at ignition are presented for methane, ethane, ethylene and acetylene in stoichiometric air. Radical chain mechanism analysis of reduced reaction sets demonstrates that values of effective ignition activation energies are dependent almost entirely on one or two chain-branching reactions. These results suggest that the global chemistry representing the weakly reacting regime up to ignition may be determined independent of reactor fluid mechanics and utilized in the prediction of hydrocarbon auto-ignition.

Key words:

• auto-ignition
• chemical kinetics
• simple hydrocarbons
• global chemistry