Autoignition of n-Hexane, Cyclohexane, and Methylcyclohexane in a Constant Volume Combustion Chamber

The autoignition behaviors of n-hexane, cyclohexane, and methylcyclohexane were experimentally determined and compared in a heated constant volume combustion chamber. The combustion pressures, heat release rates, and ignition and combustion delay times in the autoignition processes of these three fuels were compared in the context of changed chamber temperature, chamber pressure, and injection duration. The experimental results showed that n-hexane had the highest ignition propensity, followed by methylcyclohexane and cyclohexane. Compared to cyclohexane, the existence of methyl group in methylcyclohexane significantly increased the fuel autoignition tendency. Ambient pressure and temperature showed significant effects on fuel ignition timing and heat release histories. Generally, elevated ambient pressure and temperature led to reduced ignition and combustion delays. However, turnover temperatures existed in the ignition and combustion delays of cyclohexane, with ignition and combustion delays extended o...