A study of the low temperature autoignitionof methyl esters

摘要

The autoignition of a series of C4 to C8 fatty acid methyl esters has been studied in a rapid compressionmachine in the low and intermediate temperature region (650–850 K) and at increasing pressures (4–20 bar). Methyl hexanoate was selected for a full investigation of the autoignition phenomenology, includingthe identification and determination of the intermediate products of low temperature oxidation. Theoxidation scheme and overall reactivity of methyl hexanoate has been examined and compared to the reactivityof C4 to C7 n-alkanes in the same experimental conditions to evaluate the impact of the ester functionon the reactivity of the n-alkyl chain. The low temperature reactivity leading to the first stage of autoignitionis similar to n-heptane. However, the negative temperature coefficient region is located at lower temperaturethan in the case of the n-alkanes of corresponding reactivity. An evaluation of the distribution ofesteralkyl radicals R(·)and esteralkylperoxy radicals ROO(·) gives an insight into the main reaction pathways.