Experimental and kinetic modeling studies on the auto-ignition of methyl crotonate at high pressures and intermediate temperatures

Biofuels, including biodiesel have the potential to partially replace the conventional diesel fuels for low-temperature combustion engine applications to reduce the CO2 emission. Due to the long chain lengths and high molecular weights of the biodiesel components, it is quite challenging to study the biodiesel combustion experimentally and computationally. Methyl crotonate, a short unsaturated fatty acid methyl ester was chosen for the chemical kinetic study as a model biodiesel fuel. Auto-ignition experiments were carried out in a rapid compression machine at pressures of 20 and 40 bar under diluted conditions over a temperature range between 900 K and 1074 K, and at different equivalence ratios (φ = 0.25, 0.5 and 1.0). The updated mechanism showed satisfactory agreement with the ex- perimental data with significant improvements in low-temperature ignition behavior. The key reactions at various combustion conditions and the improved reactivity of the modified mechanism were analyzed by performing sensitivity and path flux analysis. The importance of low-temperature pathways in predicting the ignition behavior of methyl crotonate at intermediate and low temperatures was demonstrated.