Dynamic modeling of combustion and gas exchange processes for controlled auto-ignition engines

This paper is concerned with the development of a simple physical model of a gasoline engine cycle where the energy release is via controlled auto-ignition. It uses simple thermodynamic concepts, and well-established gas exchange and heat transfer sub-models to predict the pressures and temperatures in the engine cycle. The combustion event itself is modelled in a semi-empirical fashion. The model is an important extension of existing single-zone models and it persists between multiple cycles, enabling the capture of the cycle-to-cycle exhaust gas coupling. The model was compared with data obtained at steady engine running conditions, and good agreement was found. Controlled auto-ignition was attained by diluting the mixture with exhaust gas trapped in the cylinder, as a result of an early exhaust valve closing.