Simulation of misfire and strategies for misfire recovery of gasoline HCCI

Abstract

In HCCI mode with negative valve overlap, the understanding of the engine behavior in case of misfire and delayed combustion is important to provide a complete control strategy. A hybrid continuous zero dimensional model for gasoline HCCI, based on simplified chemical kinetics and a separate airflow model is introduced. CHEMKIN is used to simulate the chemical kinetics, whereas the airflow and the injection is simulated using MatLab. The model is compared to experimental data. The introduced model is used to analyze the effect of misfire and late combustions on the dynamics of the system. A state transition map is proposed to distinguish between misfire with and without recovery. Control strategies to improve the misfire recovery are suggested.

Cyclic Variability and Dynamical Instabilities in Autoignition Engines With High Residuals

“…In summary, the developed model compared to these previous low-order models [12]- [17], [34] captures the coupling introduced by the unburned fuel mass that has been identified as an important mechanism, in addition to charge temperature, for explaining the high CV [4]. In comparison with higher fidelity models, such as [26] and [27], the developed second-order model (25) captures the main mechanisms and is more amenable for nonlinear control development. Finally, it can be noted that all the previously mentioned HCCI models are deterministic while the model of the residual gas fraction (24) introduces a stochastic element, which is essential in order to reproduce the dynamic evolution observed in experiments as shown in the remainder of this paper.…”

“…4 and 5 for the outputs (26), combustion phasing, and heat release during main combustion. The experimental return maps immediately show nonlinear dynamical features.…”

“…The stability of the model is first investigated through a bifurcation analysis on the underlying deterministic model in (25) and (26) by assuming that the residual gas fraction x r (k) is constant. After that, numerical simulations show the dynamical behavior of the complete model with noise when x r (k) is described by (24).…”

“…The stability of a cycle of period n is determined analogously by studying the composition of the map n times, e.g., F(F(x * ; x r ); x r ) for n = 2. The fixed point curve is finally transformed with the output equations (26) to produce the diagrams in Fig. 6.…”

“…Misfire in HCCI is studied in simulation using models, including chemical kinetics and gas flows in [26] and a simplified eight-state model in [27]. The approach followed here includes only the dominating mechanisms of temperature and unburned fuel as identified through the experiments in [4], [6], and [24].…”