Abstract: In order to investigate the ignition characteristic of methyl trans-3-hexenoate under homogeneous charge compression ignition conditions, autoignition experiments of methyl trans-3-hexenoate were carried out through a rapid compression machine at compressed pressures of 1.1, 1.5 and 2.0 MPa with equivalence ratios of 0.5, 1.0 and 1.5. The ignition delay of methyl trans-3-hexenoate was compared with that of methyl hexanoate at compressed pressures of 1.5 and 2.0 MPa with equivalence ratio of 1.0. Besides, simulations were performed with CHEMKIN-PRO software. Sensitivity analysis and reaction pathway analysis were conducted to find out the important elementary reactions that control ignition. The effect of n-butanol on ignition delay was studied by adding n-butanol in methyl trans-3-hexenoate. It was found that as the equivalence ratio decreased, the maximum combustion pressure reduced and the ignition delay of methyl trans-3-hexanoate increased. The addition of n-butanol increased the ignition delay, and larger ignition delay was measured with higher content of n-butanol. It was also found that the ignition delay of methyl trans-3-hexenoate decreased with the increase of the compressed pressure. Compared with methyl hexanoate, methyl trans-3-hexenoate features only one stage ignition and no obvious negative temperature coefficient phenomenon. This was due to the existence of carbon-carbon double bond structure in methyl trans-3-hexenoate. This study measured the ignition delay of methyl trans-3-hexenoate and revealed the effect of carbon-carbon double bond on the autoignition characteristic of methyl trans-3-hexenoate.

Key words: rapid compression machine, ignition delay, methyl trans-3-hexenoate, methyl hexanoate, carbon-carbon double bond, n-butanol