Dynamics of Homogeneous Charge Compression Ignition (HCCI) Engines with High Dilution

This paper analyzes the stability of the autoignition process of homogeneous charge compression ignition (HCCI) engines in light of the cycle-to-cycle thermal feedback due to the high percentage of exhaust dilution. The influence of heat transfer and the cooling system on the system stability is investigated. The returning map and the stability of the multiple steady state equilibria are confirmed with a high order dynamic nonlinear model, which includes manifold filling and composition dynamics and has been validated both at steady state and during transient. It is shown that the autoignition, which is based on high exhaust gas recirculation and thus strong cycle-to-cycle temperature coupling, can depart from the region of attraction of a stable equilibrium during large and fast changes in fueling level.