The auto-ignition of propane at intermediate temperatures and high pressures

The results of a new experimental programme to measure auto-ignition delay times in mainly lean (phi =0.5) propane-air mixtures at intermediate temperatures in the range 850 K upwards and pressures 5-40 bar are described. The delays are compared to predictions obtained by the integration of two detailed chemical kinetic reaction schemes. Experimentally, a decrease in activation energy was observed at around 1000 K. The work shows that extrapolation of ignition delays obtained at high temperatures T > 1000 K can lead to significant overestimation of the actual delay times at lower temperatures. Despite the introduction of additional key reactions the kinetic schemes used could not fully reproduce the delay times observed experimentally at temperature below ca. 1000 K.