Skeletal Mechanism Generation for High-Temperature Combustion of H₂/CO/C₁–C₄ Hydrocarbons

The development of the combustion mechanism for hydrogen (H₂) and C₁–C₄ hydrocarbon fuels plays critical roles in many combustion systems. In the present work, a general framework to develop an efficient skeletal mechanism, which can maintain both accuracy of predicted combustion properties and chemical reality, has been established on the basis of the combination of the directed relation graph method for mechanism reduction and the element flux analysis method for reaction pathway analysis. Within the framework, a skeletal mechanism with 56 species and 428 reactions is developed from a detailed mechanism, including 111 species and 784 elementary reactions, for high-temperature combustion of H₂, and C₁–C₄ hydrocarbons. Errors in the predicted combustion properties will be introduced via removing species from detailed mechanisms. Therefore, systematical error analysis is first performed for ignition over a wide range of conditions, including temperature, pressure, and equivalence ratio, to check the robustness of the skeletal mechanism. Results show that the accuracy of the skeletal mechanism in the prediction of ignition for hydrogen, methane, ethylene, ethane, and propene is within 5% and no more than 10% for propane and <i>n</i>-butane. Time-integrated element flux analysis is subsequently used as an efficient method to check the chemical reality of the skeletal mechanism. The results indicate that the skeletal mechanism maintains the major reaction paths for targeted fuels. Finally, the skeletal mechanism is validated via the predictions of ignition, laminar flame speed, species profiles, and diffusion counter-flow flame simulations, and the use of the skeletal mechanism in the development of simplified high-temperature combustion mechanism for large alkanes is also performed