A detailed chemical kinetic model has been developed for methane oxidation which is applicable over a wide range of operating conditions. A reaction mechanism, originally developed for high-temperature methane oxidation, was expanded and extended to include reactions pertinent to the lower temperature, elevated pressure conditions encountered in the flow reactor experiments performed in the study. The resulting 207-reaction, 40-species mechanism is capable of reproducing the experimental species concentrations for each of the cases studied. The concentration profiles of reactant, intermediate, and product species, including CH4, CH2O, CH3OH, H2, C2H6, C2H4, CO, and CO2, were obtained in the High Pressure Optically Accessible Flow Reactor (HiPOAcFR) facility for temperatures ranging from 930 to 1000 K and pressures of 6 and 10 atm. Based on the model, no appreciable change in reaction pathway was observed over the pressure and temperature range studied, with HO2 providing the major route for CH3 oxidation. CH2O was found to be a vital intermediate for all of the CH4 oxidation paths. In addition, inclusion of trace amounts of CH2O measured at the initial sampling location into the model initial conditions greatly reduced the predicted time to onset of fuel disappearance and enhanced the model agreement. This result is consistent with past engine studies which have found that CH2O is a significant pro-knock additive when added to a methane base fuel. The expanded reaction mechanism was also tested against shock-tube ignition delay and laminar flame speed data and was found to be in good agreement with the relevant experimental data.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Chemical Engineering
- Fuel Technology
- Energy Engineering and Power Technology
- General Physics and Astronomy