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Efficient Additivated Gasoline Lean Engine

Periodic Reporting for period 2 - EAGLE (Efficient Additivated Gasoline Lean Engine)

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

The EAGLE project (Efficient Additivated Gasoline Lean Engine) aims at improving the energy efficiency of European road transport vehicles by developing a highly efficient gasoline engine adapted for future electrified powertrains. The maximal efficiency of gasoline engines is usually lower than 40% because of various energy losses. By combining new advanced technologies, the EAGLE project is designing an innovative engine concept to reach a peak efficiency of 50%. According to various studies, the market share of gasoline HEV and PHEV in Europe in 2030 should be greater than 35%. In this context, a multi-mode hybrid architecture is considered in the EAGLE project in order to support the European automobile industry to reach the forthcoming CO2 emissions targets while complying with standards in terms of particulates and NOx emissions in real driving conditions.

The technical objectives of EAGLE are:
- to develop an ultra-lean gasoline engine using insulation coatings, an active pre-chamber ignition system, and hydrogen as a combustion enhancer;
- to set up a closed loop combustion control strategy for lean mixtures;
- to optimize NOx after-treatment systems for ultra-lean combustion;
- to develop new models to simulate the impacts of hydrogen, coatings, and active pre-chamber ignition systems;
- to demonstrate the benefits of all these technologies on a multi-cylinder engine.

The EAGLE consortium is composed of nine complementary partners from four European countries: IFP Energies nouvelles, FEV GmbH, Universita degli studi di Napoli Federico II, Renault SAS, Universitat Politecnica de Valencia, RWTH Aachen (Lehrstuhl für Verbrennungskraftmaschinen), Saint-Gobain Centre de Recherches et d'Etudes Européen, Continental Automotive GmbH, Continental Automotive France SAS. The project also includes two third parties: Saint-Gobain Coating Solutions as a third party of Saint-Gobain Centre de Recherches et d'Etudes Européen, and Continental Automotive Italy as a third-party of Continental Automotive GmbH. The total requested grant is EUR 5,993,062. EAGLE is a Research and Innovation Action within GV-02-2016 and for which the EU funding rate is 100%.
According to various studies, the market share of gasoline HEV and PHEV in Europe should still be greater than 35% in 2030. In this context, a multi-mode hybrid architecture is considered in the EAGLE project in order to improve the efficiency in real driving conditions and to take into account broad customer requirements worldwide. Some first vehicle simulations have been performed to evaluate the benefits of this multi-mode hybrid powertrain and to identify the main vehicle parameters affecting CO2 emissions considering the highly efficient internal combustion engine (ICE) that will be developed in the EAGLE project. Different scenarios were analysed depending on the driving cycles, the vehicle architecture (S/S, HEV, PHEV), and the maximal brake thermal efficiency of the ICE. Results show that PHEV architectures should be able to reach CO2 emissions of 50 g/km (WLTC) considering a C-class vehicle.

Several technologies have been developed during the first and second reporting periods (from October 2016 until September 2019) in order to significantly increase the efficiency of the ICE.

The impact of H2 as a combustion enhancer has been demonstrated and peak indicated efficiencies higher than 47% can be achieved with ultra-lean mixtures (lambda = 2). Thanks to dilution and to hydrogen properties, PN and NOx emissions can also be decreased. However, the main hurdle to overcome regarding H2 supplementation remains the overall energy efficiency, especially for on-board hydrogen production.

A pre-chamber ignition system has also been designed to support the combustion process in lean conditions. Several versions of this ignition system were experimentally assessed with various single cylinder engine configurations. Extreme dilution levels (up to lambda = 3) can be achieved while ensuring a stable combustion process. Maximal indicated efficiencies above 47% at lambda = 2 are also demonstrated, combined with possible NOx emissions lower than 30 ppm at low load.

Additionally, smart insulation coatings are being developed to reduce the heat loss. During the first reporting period, the specifications of these coatings have been defined based upon 0D/1D numerical investigations and some first coatings have been experimentally assessed. This development was pursued during the second reporting period mainly by numerical investigations (3D CFD) which confirm the impact of coating on certain combustion parameters but also the very limited final potential impact on efficiency, indicating thus a complex mechanism that has not yet been explained. In parallel, additional efforts were made to improve the exhaust insulation in order to maximize the available enthalpy for the turbocharging system.

The definition of the aftertreatment system has also made significant progress during the second reporting period, including especially the definition of the NOx storage catalyst. The performance of various materials were quantified with granules and then with mini catalysts, in terms of light-off and in terms of NOx storage capacity in lean conditions and in lean-rich cycles. A lean NOx trap in full size scale is finally planned for the end of 2019.

Some of these advanced technologies have already been integrated and simultaneously evaluated on a single cylinder engine in 2018 with a specific closed loop combustion control strategy. At different levels, they will also be implemented on the final EAGLE multi-cylinder engine demonstrator for which additional solutions have been identified to further increase the maximal efficiency.

All of these developments have been supported by vehicle and engine 0D simulations that have helped to consolidate the boundary conditions associated with a highly hybridized application equipped with a high efficiency ultra-lean engine. During the third and last period, the performance of the final multi-cylinder engine demonstrator including the aftertreatment system will be assessed at the test bed in terms of effic
A new 0D/1D model has been developed to simulate a pre-chamber ignition system. New simulation know-how and methodologies have also been defined regarding hydrogen-enhanced combustion and insulation coatings. Finally, in order to evaluate the potential of the technologies developed in the EAGLE project, multi-cylinder and vehicle simulations are also being performed, which require advanced control strategies in order to optimize the various actuators settings and engine use over real driving cycles.

The pre-chamber ignition system that is already known for very large bore engines has been transferred to passenger car applications in the frame of the EAGLE project. This ignition system will be implemented on the final combustion system and combined with hydrogen injection, and with a closed loop combustion control in order to maximize the air dilution rate while ensuring good combustion stability. These technologies have been first tested with a single cylinder engine in 2018, and will be further evaluated in 2019-2020 with a multi-cylinder engine. In addition to materials characterization at the laboratory gas bench, an innovative full size lean NOx trap will also be provided for the final evaluation of the EAGLE multi-cylinder engine.
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