Model-Based Control of BMEP and NOx Emissions in a Euro VI 3.0L Diesel Engine

Abstract

A model-based approach to control BMEP (Brake Mean Effective Pressure) and NOx emissions has been developed and assessed on a FPT F1C 3.0L Euro VI diesel engine for heavy-duty applications. The controller is based on a zero-dimensional real-time combustion model, which is capable of simulating the HRR (heat release rate), incylinder pressure, BMEP and NOx engine-out levels. The real-time combustion model has been realized by integrating and improving previously developed simulation tools. A new discretization scheme has been developed for the model equations, in order to reduce the accuracy loss when the computational step is increased. This has allowed the required computational time to be reduced to a great extent. The real-time combustion model has been first calibrated and assessed at both steady-state and transient conditions, on the basis of experimental data acquired at the highly dynamic test bench of ICEAL-PT (Internal Combustion Engines Advanced Laboratory -Politecnico di Torino), in the frame of a research activity in collaboration with FPT Industrial. The model has then been used to realize a model-based control of BMEP and NOx emissions. In particular, the controller provides the injected fuel quantity and the injection timing of the main pulse, for given targets of BMEP and engine-out NOx levels. Finally, the developed controller has been tested on a rapid prototyping device (ETAS ES910) through HiL (Hardware-in-the-Loop) techniques, and demonstrated to have realtime capability.

A New Control-Oriented Semi-Empirical Approach to Predict Engine-Out NOx Emissions in a Euro VI 3.0 L Diesel Engine

“…• Finally, it was demonstrated that the proposed method is physically consistent, since it maintains a high accuracy even when the number of points used for calibration is very low, and that it requires a much smaller computational time than the previous model proposed in [8].…”

“…After a general discussion about the NOx formation process and some recalls on the previous semi-empirical NOx model proposed by the authors in [8] (Section 3.1), the identification of the input variables of the proposed NOx model is described in Section 3.2, while the NOx model is presented in Section 3.3. Section 3.4 reports a quick summary on the predictive combustion model that is necessary to adopt when using the previous semi-empirical NOx model described in [8].…”

“…Section 3.4 reports a quick summary on the predictive combustion model that is necessary to adopt when using the previous semi-empirical NOx model described in [8]. Some considerations concerning the model recalibration when applied to different engines are finally reported in Section 3.5.…”

“…The approach proposed in [20] was subsequently revised in [8]: the 'T bmax,main ' was replaced by the 'T b,MFB50 ' term (i.e., the burned gas temperature evaluated at MFB 50 ). The 'T b,MFB50 ' term is in fact easier to estimate, and its utilization does not lead to a deterioration of the model accuracy.…”

“…The 'T b,MFB50 ' term is in fact easier to estimate, and its utilization does not lead to a deterioration of the model accuracy. Moreover, in [8] the stoichiometric in-cylinder charge-to-fuel ratio α u st was replaced by the intake oxygen concentration 'O 2 ', since the two quantities are closely related to each other, but intake O 2 concentration can be evaluated more easily (it can even be measured by a sensor). However, the revised formulation proposed in [8] still requires the adoption of a predictive combustion model, in order to evaluate the 'T b,MFB50 ' term.…”