Algorithmic identification of the reactions related to the initial development of the time scale that characterizes CH4/air autoignition

The reactions responsible for the initial development of the time scale that characterizes the autoignition of a homogeneous stoichiometric CH4/air mixture are identified algorithmically using the computational singular perturbation method. The analysis considers a wide range of initial temperatures and pressures, located below and above the explosion limit. The major role of reactions CH3+O2CH3O+O (at high temperatures), CH3+O2CH2O+OH (at low temperatures), and CH2O+O2HCO+HO2 (at intermediate temperatures) is identified. The results provide some additional insights regarding the significance to the initiation of the process of some reactions that are generally considered to become active at later times.