Shock-tube measurements and kinetic modeling study of methyl propanoate ignition

Ignition delay times of methyl propanoate (MP) were measured in a shock tube over the temperature range of 1040-1720 K, pressures of 1.2-10 atm, fuel concentrations of 0.5-2.0%, and equivalence ratios of 0.5-2.0. Through multiple linear regression, a correlation for the tested ignition delay times was obtained, and the measured data were also compared to the previous data. Two available MP models (Princeton model and Westbrook model), were used to simulate the experimental data. Results suggest that further modifications on the available MP models are necessary. The modified MP model, consisting of 318 species and 1668 reactions, was proposed on the basis of previous studies, and it gives better prediction on the MP ignition delay times under all tested conditions than those of the other two available models. The modified MP model was further validated against the MP pyrolysis data and laminar flame speeds, and reasonable agreements were achieved. Sensitivity analysis reveals that the small radical reactions play key important roles in MP high-temperature ignition, while some fuel-specific reactions also exhibit relatively large sensitivity coefficients. Reaction pathway analysis indicates that MP is dominantly consumed through the H-abstraction reactions.