n-Heptane oxidation in a high-pressure flow reactor

The oxidation properties of n-heptane have been investigated by conducting experiments in a laminar flow reactor at pressures of 21 and 100 bar, near-stoichiometric (phi=0.9$\varPhi =0.9$) and fuel-lean conditions (phi=0.1$\varPhi =0.1$), and temperatures of 450-900 K. At 21 bar and stoichiometric conditions, a negative temperature coefficient (NTC) region was detected around 600 K. At increased pressure or oxygen concentration, the NTC behavior was much less pronounced. The observed concentration profiles for the major species were compared to predictions with selected literature mechanisms. While all models provided a satisfactory agreement for the n-heptane profiles at 21 bar fuel lean conditions and at 100 bar, only the mechanisms from NUI and Polimi captured the NTC behavior at 21 bar and stoichiometric conditions. The model from Zhang et al. provided the best overall agreement and was selected for detailed comparison with species concentrations and used in analysis of reaction paths and reaction sensitivity under the present conditions.