Experimental and Kinetic Modeling Study on High-Temperature Autoignition of Cyclohexene

Cyclohexene is an important intermediate during the oxidation
of
cycloalkanes, which comprise a significant portion of real fuels.
Thus, experimental data sets and kinetic models of cyclohexene play
an important role in the understanding of the combustion of cycloalkanes
and real fuels. In this work, an experimental and kinetic modeling
study of the high-temperature ignition of cyclohexene is performed.
Ignition delay time (IDT) measurements are carried out in a high-pressure
shock tube (HPST). The studied pressures are 5, 10, and 20 bar; the
equivalence ratios are 0.5, 1.0, and 2.0; and the temperatures range
from 980 to 1400 K for IDT in HPST. It is shown that the IDTs of cyclohexene
exhibit Arrhenius behaviors as a function of temperature, and the
IDTs decrease as the equivalence ratio and pressure increase. The
experimental results are simulated using three previous detailed kinetic
mechanisms and an updated detailed mechanism in this work. The updated
detailed kinetic mechanism exhibits good agreement with experimental
results. Reaction path analysis and sensitivity analysis are performed
to provide insights into the chemical kinetics controlling the ignition
of cyclohexene. The results demonstrate that different detailed kinetic
mechanisms are significantly different, and there are still no unified
conclusions about the major reaction path for cyclohexene oxidation.
However, it is worth noting that the abstraction reaction by oxygen
at the allylic site and the submechanism of cyclopentene are of significant
importance for the accurate prediction of IDTs of cyclohexene. The
present experimental data set and kinetic model should be valuable
to improve our understanding of the combustion chemistry of cycloalkanes.