Shock-Tube Experiments and Kinetic Modeling of Toluene Ignition

Recent ignition delay time studies of toluene ignition (using shock tubes and rapid-compression machines) have not achieved a strong consensus at intermediate temperatures (900-1200 K) and high pressures (near 50 atm). However, the development and refinement of reaction mechanisms for toluene at engine-relevant conditions demand an accurate knowledge of these ignition delay times. To help resolve this issue, we have measured ignition delay times for toluene/air mixtures (phi = 1.0) at high pressures (near 50 atm) over the temperature range of 966 to 1211 K using pressure and emission measurements behind reflected shock waves. The new ignition delay times were found to be in good agreement with the previous study of Davidson et al. [Davidson, D. F., Gauthier, B. M., and Hanson, R. K., Shock Tube Ignition Measurements of Iso-Octane/Air and Toluene/Air at High Pressures, Proceedings of the Combustion Institute, Vol. 301, 2005, pp. 1175-1182.]. Although the preignition pressure time histories varied with the shock-tube loading protocol (e.g., cleaning and passivating), the ignition delay times were not significantly affected. Ignition delay time measurements were also compared with the predictions of several current toluene reaction mechanisms, and updated reaction rate values were suggested to improve modeling performance.