Comparative Study of the Autoignition of Methyl Decenoates, Unsaturated Biodiesel Fuel Surrogates

The autoignition of methyl 9-decenoate and a mixture of methyl 5-decenoate and methyl 6-decenoate [methyl 5(6)-decenoate], biodiesel fuel surrogate compounds structurally representative of unsaturated compounds found in fatty acid methyl ester (FAME) fuels, has been studied using the shock tube technique. Measurements of ignition delay times were made in reflected shock-heated gases at pressures around 20 atm for fuel/air mixtures at equivalence ratios of 0.5, 1.0, and 1.5 and at a wide range of temperatures from 700 to 1300 K, spanning a range of temperatures relevant to autoignition in compression ignition engines. A comparison of ignition delay times for the methyl decenoates and methyl decanoate illustrates the influence of the presence and location of a double bond within the methyl ester carbon chain on low- and high-temperature reactivities. At high temperatures (>900 K), the three surrogate components have indistinguishable ignition delay. While in the negative temperature coefficient (NTC) and lo...