A Reduced Model of HCCI Combustion in View of Application to Model Based Engine Control Systems 2006-01-3297

Homogeneous Charge Compression Ignition (HCCI) combustion process is controlled by chemical kinetics which are dependent on the engine operating conditions. To reduce the number of tests needed for calibration, a computationally efficient model is needed for the entire engine operating range. The goal of this study is to provide the car manufacturers with a simple physical HCCI combustion model to assist engine tuning and engine management system optimization. The proposed model without chemical kinetics is reduced to two state variables: the temperature and the mass fraction of burning fuel. The model is driven by two functions γ_LT(T) and γ_HT(T) modeling respectively the dynamic of the first stage oxidation and the rapid transition to the main ignition. Different parameters are introduced and calibrated function of engine inlet conditions. The results are compared with a model with included chemistry and discussed. The proposed two state variables model is able to reproduce correctly the delays of the cool flame and the main ignition as well as the phasing between the two stages. The model has been compared to Renault engine experimental data. Model against experimental data shows overall satisfactory agreement