Auto-ignition of aromatic and aliphatic Diesel fuel components: High-pressure shock-tube experiments and kinetic modeling for toluene and n-heptane

The auto-ignition of toluene and n-heptane as model fuels for Diesel fuel components have been studied in a highpressure shock tube under engine-relevant conditions. Toluene/air and n-heptane/air mixtures as well as toluene/nheptane/air (10/90% and 40/60% by volume) have been investigated over a wide temperature range (700 – 1200 K), = 1.0 and 0.5 and 40 bar behind reflected shock waves. A kinetic mechanism based on the detailed Lawrence Livermore PRF (primary reference fuel) mechanism [1] extended with a toluene submechanism has been tested against the experimental ignition delay times and calculations for engine-relevant pressures and temperatures have been performed. The temporal variation in toluene concentration in the pre-ignition phase is determined relative to the base fuel and the pressure rise induced by the heat release.