Modeling of HCCI engine combustion for control analysis

Operation of homogeneous charge compression ignition (HCCI) engines are very sensitive to timing variations in the combustion of the air-fuel charge mixture and require precise control of the ignition instant to run properly. It is therefore essential to understand the characteristics of timing variations under various operating conditions in order to find suitable control strategies. This paper presents a first step towards the construction of an HCCI engine model aimed at studies on timing control strategies. The goal is to (qualitatively) reproduce the timing effects that may be observed on a real engine. The proposed model includes a lumped chemical kinetic model for hydrocarbon fuels to predict autoignition. Single-cycle simulations are compared with experimental results from a real engine to validate the model. Comparisons are also made with a model based on the knock-integral.