Comparison of autoignition characteristics of n-heptane,methylcyclohexane and toluene

The autoignition characteristics of three C7 hydrocarbon fuels,n-heptane,methylcyclohexane and toluene,were comparatively investigated.Ignitions were performed behind the reflected shock waves in a shock tube.The ignition delay times of these fuels were measured at the same igintion conditions with constant fuel mole fraction of 1.0%,equivalence ratio of 1.0,ignition pressure of 1.0×105 Pa(one more 2.0×105 Pa for n-heptane)and temperatures of 1 166-1 662 K.The correlation formula of ignition delay dependence of three fuels on igintion conditions was deduced separately.Results show that the ignition delay time of n-heptane is the shortest while that of toluene is the longest at the same ignition conditions.The ignition delay time of methylcyclohexane is most sensitive to the temperature while that of n-heptane is the least.The comparison of current ignition delay times with the predictions of available chemical kinetic reaction mechanisms has been presented to validate the reliability of mechanisms.The important chemical reactions during the ignition process have been obtained from the sensitivity analysis.

The autoignition characteristics of three C7 hydrocarbon fuels, n-heptane, methylcyclohexane and toluene, were comparatively investigated. Ignitions were performed behind the reflected shock waves in a shock tube. The ignition delay times of these fuels were measured at the same igintion conditions with constant fuel mole fraction of 1.0%, equivalence ratio of 1.0, ignition pressure of 1.0X l0s Pa （one more 2.0X 105 Pa for n-heptane） and temperatures of 1 166 -- 1 662 K. The correlation formula of ignition delay dependence of three fuels on igintion conditions was deduced separately. Results show that the ignition delay time of n-hep- tane is the shortest while that of toluene is the longest at the same ignition conditions. The ignition delay time of methylcyclohexane is most sensitive to the temperature while that of n-heptane is the least. The comparison of current ignition delay times with the predictions of available chemical kinetic reaction mechanisms has been presented to validate the reliability of mechanisms. The important chemical reactions during the ignition process have been obtained from the sensitivity analysis.