Development and validation of a real-time model for the simulation of the heat release rate, in-cylinder pressure and pollutant emissions in diesel engines

A real-time mean-value engine model for the simulation of the HRR (heat release rate), in-cylinder pressure, brake torque and pollutant emissions, including NOx and soot, has been developed, calibrated and assessed at both steady-state and transient conditions for a Euro 6 1.6L GM diesel engine. The chemical energy release has been simulated using an improved version of a previously developed model that is based on the accumulated fuel mass approach. The in-cylinder pressure has been evaluated on the basis of the inversion of a single-zone model, using the net energy release as input. The latter quantity was derived starting from the simulated chemical energy release, and evaluating the heat transfer of the charge with the walls. NOx and soot emissions were simulated on the basis of semiempirical correlations that take into account the in-cylinder thermodynamic properties, the chemical energy release and the main engine parameters. The model is also referred to as “steady-state” as the main thermodynamic properties in the intake and exhaust manifolds, as well as the inducted mass flow rate, have been evaluated by means of cor relations that were calibrated under steady-state conditions. This has allowed a very low computational time to be obtained, so that the approach is suitable for implementation in an ECU for real-time applications. The model has been calibrated over several experimental tests carried out at a dynamic test bench at GMPT-E (General Motors powertrain-Europe). The tests include a complete engine map as well as several full-factorial variation lists of the main engine parameters, which have been conducted for seven representative operating conditions of the NEDC (New European Driving Cycle). The validation has been carried out under transient conditions over NEDC and WLTP missions, which were simulated at the dynamic test bench for a C-class vehicle.