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High efficient Particulate free Gasoline Engines

Periodic Reporting for period 2 - UPGRADE (High efficient Particulate free Gasoline Engines)

Reporting period: 2018-04-01 to 2019-09-30

The UPGRADE objective was the development of next generation Spark Ignited gasoline engines to comply with post 2020 targets, considering and optimizing the Direct Injection process (pressure level, geometry, multiple injection strategy) with regard to the fuel consumption, the nanoparticles formation process and the optimization of the after-treatment system control. The project considered the best combination of new engine technologies addressing in parallel two different combustion approaches: stoichiometric and lean-burn. Consequently, also the after-treatment system developments considered both combustion approaches providing a complete overview and assessment of both technologies. The project also included a deep analysis of the phenomenon of formation of the nanoparticles in relationship to the engine design and its operating conditions, through both experimental and numerical investigations.
Conclusion of the action:
the development of advanced technologies dedicated for SI gasoline engines was successfully completed and the reduction of 15% of CO2 (vs. 2015 best in class vehicle) was demonstrated by means of vehicle demonstrator tested by JRC both on WLTC and Real Driving tests. Even PN emissions, measured on RDE cycles with PEMS technology, are strongly below the regulated limits. In a longer perspective (beyond 2025), it has been shown that a homogeneous lean burn engine, especially in combination with a hybrid drivetrain, can contribute to even further reductions in fuel consumption / GHG emissions.
The following results are achieved:
• A new model dedicated to GDI engines able to predict soot distribution in size and to interact with detailed chemistry, together with an advanced fuel films modeling, to support the development of the next generation of clean and highly efficient GDI engines.
• An innovative in-cylinder fluid motion, so-called Swumble, was tested and assessed, showing a real breakthrough in terms of particulates emissions and an improvement of efficiency when compared to the state of the art GDI engines. This new approach could benefit to the targeted reduction of emissions of next generation high efficiency gasoline engines.
• Development and validation of predictive filtration efficiency and pressure drop models for GPFs of different cell- and wall micro-structure under soot-free and soot loaded conditions. Based on the available data, semi-empirical functions correlating the local washcoat loading with the filtration parameters as well as with the permeability of the soot-free and soot loaded wall were derived.
• Delivery of mathematical models able to predict the impact of ash accumulation on pressure drop and filtration performance of coated Gasoline Particulate Filters (cGPFs) over a wide range of operating conditions.
• A computational methodology to predict gas exchange, fuel-air mixing and pollutant emissions and specific developments to address relevant aspects such as liquid fuel properties, mass conservation in the film, ignition and flame propagation. A semi-empirical model was employed to describe the soot formation process and the validation of the computational approach was done by simulating two different engines. The IFPEn optical engine was used for a preliminary assessment; afterwards calculations were carried out for the three-cylinder engine which was extensively investigated in the context of the project. Combustion model results were presented at two international conferences in 2019.
• Development of a fully flexible set-up for transient experimental investigation on advanced turbocharging and electrically assisted boosting systems at the University of Genoa
• Development of a low voltage 12V electric supercharger (eSC) including the development of a new centrifugal compressor with improved efficiency to support such CO2 / steady state application
• Development of a low voltage 12V Belt Starter Generator system with innovative algorithms able to ensure mild-hybrid level functions at lowest cost, but no exploitation plan for this component since the market seems to be oriented towards the 48V starter system instead of 12V system.
• Development of a 2-stage boosting system capable of deliver the necessary air to be able to operate lean in a large part of the WLTP-cycle.
• Extending the lean limit by optimized in-cylinder gas motion in combination with an advanced ignition system and development of an exhaust after-treatment system for lean operation.
• Development of a stoichiometric and downsized highly boosted engine platform, with an external low pressure EGR system, high pressure GDI up to 350 bar, high compression ratio (CR 13), Variable Geometry Turbine for advanced boosting and advanced VVA actuation: the demo vehicle equipped with this engine was able to demonstrate a reduction of 15% of CO2 and a drastically reduction of PN23nm & PN10nm emissions on RDE.
Dissemination: 25 actions were carried out along the project timeframe
The new soot modeling capabilities offered by the new sectional soot model will allow car manufacturers to develop faster and better new GDI engines taking into account the production of very small particles, below 23 nm, as soon as the first design of the engine thanks to accurate soot emissions modeling. In parallel, understanding and prediction of soot formation mechanism for smaller particulates, between 10 and 23 nm, has been largely improved, allowing car manufacturers to understand technological levers that can be exploited to decrease particulate production in number and to develop the next generation of particulate free GDI engines. Based on these new tools and knowhow, an innovative in-cylinder fluid motion was tested and assessed, showing a real breakthrough in terms of particulates emissions and an improvement of efficiency when compared to the state of the art GDI engines. This new approach could benefit to the targeted reduction of emissions of next generation high efficiency gasoline engines.
The exhaust gas aftertreatment system, especially the gasoline particle filter, will be an essential part to achieve future requirements and to maximize emission control robustness in the field, in particular considering that a future particle size threshold of 10nm requires the development of solutions beyond today´s state of the art. The findings of the workpackage “Control and filtration of nanoparticles” contributed towards a competitive future of the internal combustion engine since, with the results, have been able to provide a solid basis for the development of an ultra clean vehicle as targeted in Upgrade. In a longer perspective (beyond 2025), it has been shown that a homogeneous lean burn engine especially in combination with a hybrid drivetrain can contribute to even further reductions in fuel consumption / GHG emissions. Concerning the B-segment vehicle, the 3 cylinder engine concept developed in the project will strongly impact on the competitiveness of the future engine generation. As conclusion, UPGRADE project demonstrated a potential new roadmap of gasoline engines/vehicles for current and future on road light duty transportation by means of innovative solutions. New generations of extremely efficient and clean engines are possible. The combination of Upgrade engine and electrical motor is possible in order to further increase the transport efficiency.