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Study of n-Butylcyclohexane/Air Ignition over a Broad Range of Temperatures in Shock Tube

ABSTRACT Measurements of ignition delay times for n-butylcyclohexane/air were performed over temperatures of 707–1458 K, pressures of 2.0, 5.0, and 15.0 atm, and equivalence ratios of 0.5, 1.0, and 2.0 in a heated shock tube. High temperature (>1000 K) results reveal that increasing of temperature or pressure results in a monotonous decreasing of ignition delay time at fixed equivalence ratios, effects of equivalence ratio on ignition delay are different at different pressures, and ignition delay times of fuel-lean mixture are the most sensitive to temperature. At low temperatures (<1000 K), a negative temperature coefficient (NTC) behavior of ignition was observed, and the ignition delay dependence on equivalence ratio is much stronger than that at high temperatures. The current ignition delay times of n-butylcyclohexane were compared to those of cyclohexane, methylcyclohexane, and ethylcyclohexane, and also to those of C10 fuels of n-decane and n-butylbenzene. Mechanism predictions agree well with present measured data qualitatively, and are longer than the data at most conditions. The key reactions influencing ignition delay and reaction pathways during ignition process of n-butylcyclohexane/air are different at high and low temperatures. The results obtained in this work are valuable for understanding characteristics of n-butylcyclohexane ignition and provide new experimental data for refining kinetic mechanism of n-butylcyclohexane.