Initial development of a predictive hydrocarbon emissions model for a DI diesel engine

The drive towards lower emissions from automotive diesel engines as a consequence of strict environmental regulations has resulted in extensive R&D programmes. The modelling side of emissions work, particularly unburned hydrocarbons, is still a very complex area and the development of accurate predictive capabilities would significantly reduce test-bed time. This paper details the modelling and validation strategy that was carried out to develop a hydrocarbon predictive emission model for use within an existing diesel engine simulation program. A review of the major hydrocarbon formation processes during the combustion phase is presented and the two most significant sources, over-mixing and over-penetration, are detailed. Models are derived to simulate hydrocarbon emissions from these two processes and validation results against actual engine data are presented.