Numerical Assessment of Emission Sources for a Modified Diesel Engine Running in PCCI Mode on a Mixture of Gasoline and Diesel

Bruno Kerschgens; Anyelo Vanegas; Heinz Pitsch

doi:10.4271/2011-24-0014

Premixed charge compression ignition (PCCI) is an interesting alternative to conventional diesel combustion, as it allows very low emission levels for part load operation. The difficult control of the onset of combustion is an obstacle to the implementation of PCCI. In a recent study, different mixtures of gasoline and diesel fuel have been used in a modified diesel engine to delay the ignition and thus to allow for a substantial premixing time. For these cases, very low levels of particulate emissions have been reported. However, the emissions of CO and NO_x were considerably high.

In this study, combustion and pollutant formation in the above-mentioned modified diesel engine are simulated using the representative interactive flamelet (RIF) approach. A detailed chemical reaction mechanism for a mixture of n-heptane, iso-octane, toluene, and ethanol, serving as surrogate fuel for the diesel-gasoline blend, is used for the simulations. By systematic comparison of experimental and numerical results, an improved understanding of PCCI combustion is achieved and the origins of the CO and NO_x emissions are identified. Finally, measures to reduce these emissions while keeping the low PM levels are suggested.

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Numerical Assessment of Emission Sources for a Modified Diesel Engine Running in PCCI Mode on a Mixture of Gasoline and Diesel 2011-24-0014

SAE MOBILUS