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Efficient Additivated Gasoline Lean Engine

Periodic Reporting for period 3 - EAGLE (Efficient Additivated Gasoline Lean Engine)

Reporting period: 2019-10-01 to 2020-11-30

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:
- objective 1: to develop an ultra-lean gasoline engine using insulation coatings, an active pre-chamber ignition system, and hydrogen as a combustion enhancer;
- objective 2: to set up a closed loop combustion control strategy for lean mixtures;
- objective 3:to optimize NOx after-treatment systems for ultra-lean combustion;
- objective 4:to develop new models to simulate the impacts of hydrogen, coatings, and active pre-chamber ignition systems;
- objective 5: to demonstrate the benefits of all these technologies on a multi-cylinder engine.

The main conclusions of the action are detailed below for each objective.

Objective 1
The pre-chamber ignition system that is already known for large bore engines has been transferred to passenger car applications. This ignition system was 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.

Objective 2
Closed loop combustion control for hydrogen injection and for pre-chamber injection and ignition was developed and successfully tested on single cylinder and multi-cylinder engines.

Objective 3
In addition to materials characterization at the laboratory gas bench, an innovative full size lean NOx trap was provided for the final evaluation of the EAGLE multi-cylinder engine. The NOx storage efficiency was optimized, together also with the NH3 and N2O selectivity in order to anticipate for future possible regulations.

Objective 4
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, multi-cylinder and vehicle simulations were also performed by using advanced engine and vehicle control strategies.

Objective 5
All the technology bricks have been implemented on the final multi-cylinder engine. The electrified dual stage turbocharging system was implemented and calibrated, and the overall exhaust aftertreatment performance was in line with the expectations given the considered testing conditions.
A multi-mode hybrid architecture is considered in order to improve the efficiency in real driving conditions. Vehicle simulations were performed to evaluate the benefits of this multi-mode powertrain and to identify the parameters affecting CO2 emissions. Different scenarios were analysed and results show that PHEV architectures should reach 50 gCO2/km (WLTC) considering a C-class vehicle.

The impact of H2 as a combustion enhancer was demonstrated and 47% peak indicated efficiency was achieved at lambda = 2, while PN and NOx emissions are also decreased. The main hurdle to overcome regarding H2 supplementation remains the overall energy efficiency for on-board H2 production. Codes for 3D CFD were also adapted to H2 combustion, and can be used for various applications. “H2 supplementation” can be an alternative path to FCEVs and to dedicated hydrogen ICE.

A pre-chamber ignition system was designed to support the combustion in lean conditions. Extreme dilution (up to lambda = 3) was achieved with a stable combustion process. 47% maximal indicated efficiency at lambda = 2 is also demonstrated, combined with less than 30 ppm NOx at low load. Key players are now investigating these ignition systems for automotive and heavy-duty applications. Further developments are on-going in several research and applied projects. 3 patents have been granted on this topic

Smart insulation coatings were developed to reduce heat loss. Coatings performance were assessed based on numerical and experimental investigations. A limited impact of coating was observed when used with a spark-ignited engine. Latest results with the final EAGLE engine concept and the final coating configuration show, however, a positive effect on heat loss reduction.
In parallel, two exhaust insulation techniques were tested: coated exhaust parts, and fiber mat insulation, and one of them showed promising result to improve the efficiency of lean engines.

A NOx storage catalyst was designed to fit the requirements of ultra-lean burn gasoline engines. The performance of various materials were quantified with granules and mini catalysts. The full size scale NSC was finally delivered for the multicylinder engine testing phase.

A closed loop combustion control applied to H2 injection, and then to pre-chamber ignition and injection was developed. Based on multi-cylinder engine tests, this strategy proved to be efficient to lower pollutant emissions and increase efficiency.

The electrified dual stage turbocharging system was calibrated for the EAGLE multi-cylinder engine and it was shown that the overall exhaust aftertreatment performance was in line with the expectations.

Several paths have been identified for further exploitation, either for industrial developments, or for other H2020 projects.

Communication and dissemination was very strong during the project, and some additional publications are still planned for 2021.
Highlights
- New 0D/1D/3D models / codes / simulation methodologies were developed for pre-chamber ignition system, hydrogen supplementation, insulation coatings, energy management.
- A pre-chamber ignition system, already known for very large bore engines, is now implemented in a small bore engine.
- Closed Loop Combustion Control is developed to stabilize combustion in extremely diluted mixtures.
- EAGLE results supported 4 PhD students, and 1 Master student. A 5th PhD student might use the EAGLE results.
- EAGLE results are included in some educational programs.
- A strong communication effort was made by the consortium, not only for scientific publications, but also for open communication towards the general public.
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