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Biodiesel-fueled engine simulations were performed using the KIVA3v-Release 2 code coupled with Chemkin-II for detailed chemistry. The model incorporates a reduced mechanism that was created from a methyl decanoate/methyl-9-decenoate mechanism developed at the Lawrence Livermore National Laboratory. A combination of Directed Relation Graph, chemical lumping, and limited reaction rate tuning was used to reduce the detailed mechanism from 3299 species and 10806 reactions to 77 species and 209 reactions. The mechanism was validated against its detailed counterpart and predicted accurate ignition delay times over a range of relevant operating conditions. The mechanism was then combined with the ERC PRF mechanism to include n-heptane as an additional fuel component. The biodiesel mechanism was applied in KIVA using a discrete multi-component model with accurate physical properties for the five common components of real biodiesel fuel.

The ignition process of fuel reactivity controlled PCCI combustion was investigated using engine experiments and detailed CFD modeling. The experiments were performed using a modified all metal heavy-duty, compression-ignition engine. The engine was fueled using commercially available gasoline (PON 91.6) and ULSD diesel delivered through separate port and direct injection systems, respectively. Experiments were conducted at a steady state-engine load of 4.5 bar IMEP and speed of 1300 rev/min. In-cylinder optical measurements focused on understanding the fuel decomposition and fuel reactivity stratification provided through the charge preparation. The measurement technique utilized point location optical access through a modified cylinder head with two access points in the firedeck. Optical measurements of natural thermal emission were performed with an FTIR operating in the 2-4.5 μm spectral region.