Oxidation kinetics of methyl decanoate in a motored engine

Abstract Low-temperature oxidation of methyl decanoate was experimentally investigated in a motored engine. The engine was operated in a premixed mode at a fixed speed of 700 rpm and an intake temperature of 125 °C. Compression ratio was varied between 5.5 and 9.0 for an equivalence ratio of 0.25. The study analyzes heat release and stable species concentrations in the oxidation products at each studied compression ratio. A gas chromatograph-mass spectrometer was used to identify and quantify the composition of the exhaust gas. More than sixty stable intermediate species were detected. Quantitative concentration measurements were carried out for selected alkenes, aldehydes, ketones, ethers, and alcohols. A Fourier transform infrared spectrometer was used to detect and quantify carbon monoxide and dioxide. The oxidation process shares features in common with alkane oxidation, with differences related to methyl ester intermediates formation specific to methyl decanoate oxidation. Specifically, the unsaturated ester methyl prop-2-enoate was generated in considerable amounts. The heat release and speciation trends show two-stage ignition and negative temperature coefficient features. The experimental data are also compared to numerical results calculated based on an existing reaction mechanism for methyl decanoate.