Shock tube ignition delay time measurements for methyl propanoate and methyl acrylate: Influence of saturation on small methyl ester high‐temperature reactivity

Abstract

AbstractWe report ignition delay time measurements for methyl propanoate (MP) and methyl acrylate (MA), carried out in a high‐pressure shock tube. Experiments were performed behind reflected shock waves across a temperature range of 989‐1 367 K, for fuel‐air mixtures at equivalence ratios of ϕ = 0.5, 1.0, and 2.0, and nominal pressures of 1 and 4 MPa. Ignition delay times were found to decrease with increasing temperature, equivalence ratio, and pressure, and are well described with correlations involving Arrhenius temperature dependence and power‐law dependence on equivalence ratio and pressure. Ignition delay times are compared with model predictions from literature kinetic models, with the models of Zhang et al (Energy & Fuels 2014; 28(11): 7194‐7202) and Bennadji et al (International Journal of Chemical Kinetics 2011; 43(4): 204‐218.) in good agreement with measured ignition delay times for MP and MA, respectively. Kinetic sensitivity analysis shows that the reactions most important for modeling ignition fall into two categories: initiation reactions (ie, decomposition and H‐atom abstraction) and C0‐C1 chemistry controlling the pool of small radicals. The unsaturated MA was observed to have lower reactivity than MP, due to its greater bond strengths for C─C and C─H bonds, resulting in slower rates for initiation reactions.