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Coordinated EGR-VNT control based on the intake air mass observer is presented in this paper to deal with the transient AFR control of turbocharged diesel engine. The air mass model embedded in the observer is a Takagi-Sugeno fuzzy neural network trained with transient simulation results. It can predict the charged fresh air mass entering the cylinder. In a high load region, when EGR is not effective, the coordinated EGR-VNT control will also bring benefits to the transient air-fuel-ratio control. The simulation results of TDI engine model verify that the transient control strategy will allow a better control of the intake air mass, and thus improve air-fuel-ratio control and reduce NOx emission in transients.

A quasi-dimensional multi-zone model for diesel spray combustion has been developed. The model contains most of the physical processes of diesel spray combustion, and is simplified and economical. The zone formation is based on the fuel injection parameters. For the wall jet penetration velocity, a new equation is used based on the effect of the impinging free jet on the wall jet. For the fuel evaporation, an approximate solution of the instantaneous variations of droplet diameter is given in the simple algebraic equations based on the individual effect of the evaporation and the heat transfer from ambient gas. The soot emission sub-model calculates the soot concentration. This model has been applied for a direct injection diesel engine. The calculated results have shown a reasonable agreement with the experimental results. A parametric study has been carried out.