Evaluating the Potential of a Direct-Injection Constant-Volume Combustion Chamber as a Tool to Validate Chemical-Kinetic Models for Liquid Fuels

Abstract

ABSTRACTChemical-kinetic mechanisms for low-volatility hydrocarbons and alternative fuels are mostly scarce or not validated, primarily due to the lack of a convenient experimental platform to investigate fundamental ignition and combustion behavior for such fuels. This work reports experimental measurements of ignition delays and related combustion behavior of n-heptane in a direct-injection constant-volume combustion chamber, for pressures ranging from 0.2 MPa to 1.0 MPa and temperatures ranging from approximately 390°C to 500°C while holding the global equivalence ratio constant at 0.62. Results showed clear two-stage ignition and negative temperature coefficient behavior, and data at higher pressures agreed closely with predictions from a perfectly-stirred-reactor model. At lower pressures, impingement of liquid fuel on the chamber wall likely caused experimental data to deviate significantly from model predictions. Overall, this work strongly suggests that this experimental platform can be used to validate chemical kinetics of liquid fuels.