A Comparison of HCCI Ignition Characteristics of Gasoline Fuels Using a Single-Zone Kinetic Model with a Five Component Surrogate Fuel 2008-01-2399

While gasoline surrogate development has progressed in the areas of more complex surrogate mixtures and in kinetic modeling tools and mechanism development, it is generally recognized that further development is still needed. This paper represents a small step in supporting this development by providing comparisons between experimental engine data and surrogate-based kinetic models. In our case, the HCCI engine data comes from a port-injected, single-cylinder research engine with intake-air heating for combustion phasing control. Timing sweeps were run at constant fuel rate for three market gasolines and five surrogate mixtures. Modeling was done using the CHEMKIN software with a gasoline mechanism set containing 1440 species and 6572 reactions. Five pure compounds were selected for the surrogate blends and include iso-octane, n-heptane, toluene, methylcyclohexane, and 1-hexene. Engine and simulation results were completed for all fuels and comparisons are made relative to fuel chemistry and properties. Results indicate that the surrogate blends do not accurately reproduce the ignition trends of the market fuels when matched to the market fuels by RON alone, but that matching based on a combination of MON and sensitivity does provide closer agreement between the market and surrogate fuels. The single zone kinetic model accurately reproduces the ignition behavior of the surrogate fuels. Limited multi-zone modeling runs show a reasonable match between actual and modeled emissions and point to needs for further model tuning.