Reduced Chemical Reaction Mechanisms: Experimental and HCCI Modelling Investigations of Autoignition Processes of n-Heptane in Internal Combustion Engines

A skeletal (27 species and 21 reactions) chemical reaction mechanism for n-heptane is constructed from a semi-detailed n-heptane mechanism (57 species and 290 reactions) of the Chalmers University of Technology in Sweden. The construction of the reduced mechanisms is performed by using reduction methods such as the quasi-steady-state assumption and the partial equilibrium assumption. The inlet temperature and the equivalence ratio are varied and ignition delays are calculated from pressure curves, using the reduced n-heptane mechanism for several engine parameters adhering to HCCI conditions: inlet temperature (303 ~ 365 K) and equivalence ratio (0,2 ~ 0,4). Subsequently the reduced mechanism is successfully numerically validated against the Chalmers mechanism and another more detailed mechanism provided LLNL (Curran et al. with 561 species and 2539 reactions).

Furthermore the results obtained from the reduced n-heptane mechanism are experimentally validated by experiments performed on a CFR engine, using the same parameters.