Speciation studies of methyl butanoate ignition

The current work presents the results of an experimental study of the intermediates formed during ignition of methyl butanoate (C5H10O2) and air mixtures. A rapid-sampling system and the University of Michigan rapid compression facility were used to acquire gas samples at conditions of P = 10.2 atm and T = 985 K using mixtures of χmb = 0.96%, χO2χO2 = 20.79%, χN2χN2 = 52.89%, and χAr = 25.25% (mole fraction, percent basis); corresponding to ϕ = 0.30 and an inert gas to O2 molar ratio of 3.76. The samples were analyzed using gas chromatography. Quantitative measurements of mole fraction time-histories of methane, ethane, propane, ethene, propene, and 1-butene are compared with model predictions based on a reaction mechanism developed in previous work. The methane and ethene time-histories are in excellent agreement (within ∼20%), while propene and ethane are underpredicted by the model. Sensitivity analysis shows ignition is controlled primarily by competition between H2O2 and HO2 kinetics at these conditions. Reaction path analysis shows the methyl butanoate fuel consumption is dominated by H-atom abstraction by OH.