Compact Chemical Mechanism for Autoignition and Combustion of Methylcyclohexane under Engine Relevant Conditions

摘要

A compact chemical kinetic mechanism for autoignition and combustion of methylcyclohexane (MCH)was developed and validated for a wide range of conditions, especially for low temperatures and high pressures that are most relevant to real engines. The mechanism was constructed in steps. An improved C-5-C-7 submechanism (26 species and 90 reactions) was first developed to describe fuel-cracking to form smaller fragments under high temperatures. Five modules of the C-5-C-7 submechanism were considered separately, and the rate constants were carefully estimated. A semiglobal low-temperature submechanism was developed to improve prediction of the negative temperature coefficient behaviors, which contained 4 species and 11 reactions. Isomers of intermediate radicals and faSt reactions were lumped to obtain the minimal low-temperature submechanism. Combined with a simplified C-0-C-4 kernel (40 species and 276 reactions), the final mechanism consists of 70 species and 377 reactions. Validations of the newly developed mechanism were performed using amounts of experimental data, including ignition delays in shock tubes and rapid compression machines, under a wide range of temperatures (650-2000 K), pressures (1-50 atm), and equivalence ratios (0.5-2.0), and OH concentration histories in high pressure shock tubes. Furthermore, experimental data of species concentrations and flame speeds in laminar premixed flames were also used for validation. The present mechanism showed good accuracy in predicting ignition and combustion properties over a range of parameters. Simulations using other detailed MCH mechanisms were also carried out for comparison.