Revisit of Diesel Reference Fuel (n-Heptane) Mechanism Applied to Multidimensional Diesel Ignition and Combustion Simulations

ABSTRACT Two reduced n-heptane mechanisms, previously developed in 1998 (40 species and 165 reactions) and in 2000 (65 species and 273 reactions) respectively, were revisited and the mechanism improvement was pursued. In the newly revised version, the mechanism consists of 83 species and 445 reactions. The mechanism was validated against the auto-ignition delay times of n-heptane/air mixture measured in shock-tubes (equivalence ratio ranging from 0.2 to 0.4 at 50 bar, from 0.5 to 2.0 at 13.5 bar and 41.0 bar), the free propagating speeds of laminar premixed flames (1 atm and 3 atm), and the chemical structure of a burner-stabilized laminar premixed flame (1 atm). The mechanism was applied to the three-dimensional simulations of Cummins heavy-duty diesel engine, Sandia HSDI light-duty diesel engine, and Sandia high-pressure constant-volume chamber. All the simulations were performed without any modification of the mechanism rate constants. The results demonstrate that the mechanism is able to reproduce the cool flame phenomena under the influences of temperature and EGR. The revised mechanism could provide a building block for the future improvement/development of realistic fuel mechanisms and engine soot modeling.