A Synergic Use of Innovative Technologies for the Next Generation of High Efficiency Internal Combustion Engines for PHEVs: The PHOENICE Project

Despite the legislation targets set by several governments of a full electrification of new light-duty vehicle fleets by 2035, the development of innovative, environmental-friendly Internal Combustion Engines (ICEs) is still crucial to be on track toward the complete decarbonization of on road-mobility of the future. In such a framework, the PHOENICE (PHev towards zerO EmissioNs & ultimate ICE efficiency) project aims at developing a C SUV-class plug-in hybrid (P0/P4) vehicle demonstrator capable to achieve a -10% fuel consumption reduction with respect to current EU6 vehicle while complying with upcoming EU7 pollutant emissions limits.

Such ambitious targets will require the optimization of the whole engine system, exploiting the possible synergies among the combustion, the aftertreatment and the exhaust waste heat recovery systems. Focusing on the first aspect, the combined use of innovative in-cylinder charge motion, Miller cycle with high compression ratio, lean mixture with cooled EGR and electrified turbocharger will enable a highly diluted combustion process capable to achieve a peak indicated efficiency of 47% and, at the same time, to minimize the engine out emissions. Numerical simulations were intensively exploited to reduce the engine calibration time and to preliminary assess the benefits of the abovementioned technologies. In particular, 3D-CFD simulations highlighted the capabilities of the Swumble^TM intake ports to produce an increase of about 50% of the Turbulent Kinetic Energy (TKE), while 1D-CFD models showed possible further enhancements of the brake thermal efficiency through the use of the new turbocharger (+2%) and of an aggressive Millerization of the cycle (+1.1%).

Finally, a preliminary experimental campaign, performed on the first engine prototype, confirmed the encouraging results of the simulation activity. With an AFR = 1.43 and an EGR ratio close to 5%, the PHOENICE engine showed a further improvement in the BTE up to 4% and a simultaneous reduction of the NOx emissions of more than 70% in comparison with conventional stoichiometric, undiluted operation.