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Balancing Hydraulic Flow and Fuel Injection Parameters for Low-Emission and High-Efficiency Automotive Diesel Engines

Continental-Giovanni Avolio
General Motors-Francesco Concetto Pesce, Alberto Vassallo, Giacomo Belgiorno
Published 2019-09-09 by SAE International in United States
The introduction of new light-duty vehicle emission limits to comply under real driving conditions (RDE) is pushing the diesel engine manufacturers to identify and improve the technologies and strategies for further emission reduction. The latest technology advancements on the after-treatment systems have permitted to achieve very low emission conformity factors over the RDE, and therefore, the biggest challenge of the diesel engine development is maintaining its competitiveness in the trade-off “CO2-system cost” in comparison to other propulsion systems. In this regard, diesel engines can continue to play an important role, in the short-medium term, to enable cost-effective compliance of CO2-fleet emission targets, either in conventional or hybrid propulsion systems configuration. This is especially true for large-size cars, SUVs and light commercial vehicles.In this framework, a comprehensive approach covering the whole powertrain is of primary importance in order to simultaneously meet the performance, efficiency, noise and emission targets, and therefore, further development of the combustion system design and injection system represent important levers for additional improvements. For this purpose, a dedicated 0.5 dm3 single-cylinder engine has…
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Key Fuel Injection System Features for Efficiency Improvement in Future Diesel Passenger Cars

SAE International Journal of Advances and Current Practices in Mobility

Continental Corp-Giovanni Avolio
GM Global Propulsion Systems-Alberto Vassallo
  • Journal Article
  • 2019-01-0547
Published 2019-04-02 by SAE International in United States
Diesel will continue to be an indispensable energy carrier for the car fleet CO2 emission targets in the short-term. This is particularly relevant for heavy-duty vehicles as for mid-size cars and SUVs. Looking at the latest technology achievements on the after-treatment systems, it can be stated that the concerning about the NOx emission gap between homologation test and real road use is basically solved, while the future challenge for diesel survival is to keep its competitiveness in the CO2 vs cost equation in comparison to other propulsion systems.The development of the combustion system design still represents an important leverage for further efficiency and emissions improvements while keeping the current excellent performance in terms of power density and low-end torque.The paper describes the results achieved in developing a new diesel combustion system for car application that, leveraging on the high flexibility of the latest fuel injection technology, combines outstanding power and fuel efficiency with low pollutant emissions in ultralight engine designed for lower maximum peak cylinder pressure. The study has been carried out on a 0.5l…
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The Key Role of Advanced, Flexible Fuel Injection Systems to Match the Future CO2 Targets in an Ultra-Light Mid-Size Diesel Engine

SAE International Journal of Engines

Continental GmbH, Germany-Giovanni Avolio
General Motors Global Propulsion Systems, Italy-Alberto Vassallo, Francesco Concetto Pesce
  • Journal Article
  • 03-12-02-0010
Published 2019-01-23 by SAE International in United States
The article describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through a combination of mechanical and thermodynamic efficiencies improvement. The project stemmed from the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, it is possible to reduce the engine peak firing pressure (pfp) with great benefits on reciprocating and rotating components’ light-weighting and friction for high-speed light-duty engines, while keeping the power density at competitive levels. To this aim, an advanced injection system concept capable of injection pressure greater than 2500 bar was coupled to a prototype engine featuring newly developed combustion system. Then, the matching among these features has been thoroughly experimentally examined. The results confirmed the benefits of the employment of high fuel injection pressures as a way to reduce the pfp, combining competitive performance and excellent fuel efficiency with emissions and noise, vibration, and harshness (NVH) requirements of last generation diesel engines for passenger car applications. In…
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The Key Role of Advanced, Flexible Fuel Injection Systems to Match the Future CO2 Targets in an Ultra-Light Mid-Size Diesel Engine

Continental Corp-Giovanni Avolio
GM Global Propulsion Systems-Alberto Vassallo, Francesco Concetto Pesce
Published 2018-05-30 by SAE International in United States
The paper describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through a combination of mechanical and thermodynamic efficiencies improvement.The project stemmed from the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, it is possible to reduce the engine peak firing pressure (pfp) with great benefits on reciprocating and rotating components light-weighting and friction for high-speed light-duty engines, while keeping the power density at competitive levels. To this aim, an advanced injection system concept capable of injection pressure greater than 2500 bar was coupled to a prototype engine featuring newly developed combustion system. Then, the matching among these features have been thoroughly experimentally examined.The results confirmed the benefits of the employment of high fuel injection pressures as a way to reduce the pfp, combining competitive performance and excellent fuel efficiency with emissions and Noise Vibration Harshness (NVH) requirements of last generation diesel engines for passenger car applications. In particular, the paper…
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Analysis of Diesel Injector Nozzle Flow Number Impact on Emissions and Performance of a Euro5 Automotive Diesel Engine

General Motors Company-Claudio Ciaravino
General Motors Powertrain Europe-Giovanni Avolio
Published 2012-04-16 by SAE International in United States
The present paper describes the results of a research project aimed at studying the impact of nozzle flow number on a Euro5 automotive diesel engine, featuring Closed-Loop Combustion Control. In order to optimize the trade-offs between fuel economy, combustion noise, emissions and power density for the next generation diesel engines, general trend among OEMs is lowering nozzle flow number and, as a consequence, nozzle hole size. In this context, three nozzle configurations have been characterized on a 2.0L Euro5 Common Rail Diesel engine, coupling experimental activities performed on multi-cylinder and optical single cylinder engines to analysis on spray bomb and injector test rigs. More in detail, this paper deeply describes the investigation carried out on the multi-cylinder engine, specifically devoted to the combustion evolution and engine performance analysis, varying the injector flow number. To this aim, an experimental campaign has been carried out, testing the engine in three partial load steady state operating points, representative of the European homologation driving cycle, and in full load engine conditions. The engine behaviour has been investigated performing exhaust…
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Investigation of Diesel Injector Nozzle Flow Number Impact on Spray Formation and Combustion Evolution by Optical Diagnostics

General Motors Company-Claudio Ciaravino
General Motors Powertrain Europe-Giovanni Avolio
Published 2012-04-16 by SAE International in United States
The present paper describes an experimental investigation over the impact of diesel injector nozzle flow number on spray formation and combustion evolution for a modern EURO5 light-duty diesel engine. The analysis has been carried out by coupling the investigations in non evaporative spray bomb to tests in optical single cylinder engine in firing conditions.The research activity, which is the result of a collaborative project between Istituto Motori Napoli - CNR and GM Powertrain Europe, is devoted to understanding the basic operating behaviour of low flow number nozzles which are showing promising improvements in diesel engine behaviour at partial load. In fact, because of the compelling need to push further emission, efficiency, combustion noise and power density capabilities of the last-generation diesel engines, the combination of high injection pressure fuel pumps and low flow number nozzles is general trend among major OEMs. Therefore, aim of this paper is to provide a deeper understanding about the link between the nozzle flow number, the spray and mixture formation and the consequent combustion behaviour for different nozzle geometries and…
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Compression Ratio Influence on the Performance of an Advanced Single-Cylinder Diesel Engine Operating in Conventional and Low Temperature Combustion Mode

Istituto Motori - CNR-Carlo Beatrice, Giovanni Avolio, Nicola Del Giacomo, Chiara Guido
Published 2008-06-23 by SAE International in United States
The present paper describes a detailed experimental analysis on the effect of the compression ratio on the performance of a single-cylinder research diesel engine operating with both conventional combustion and Low Temperature Combustion mode for low NOx emissions.The single-cylinder engine was developed with the same combustion system architecture of the four-cylinder FIAT 1.9 liter Multi-Jet.Starting from an engine configuration with a compression ratio of 16.5, the compression ratio was reduced to 14.5. For both the geometric configurations, engine performance was evaluated in terms of thermodynamic parameters, emissions and fuel consumption in some operating test points representative of the engine behavior running on the NEDC cycle.The results of compression ratio reduction evidenced a strong improvement in NOx-particulate trade-off coupled with penalties in unburned compounds emissions (HCs+CO) and fuel consumption, highlighting advantages and limits of low compression ratio engines employing low temperature combustion concept.
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The Effect of “Clean and Cold” EGR on the Improvement of Low Temperature Combustion Performance in a Single Cylinder Research Diesel Engine

Istituto Motori - Consiglio Nazionale delle Ricerche-Carlo Beatrice, Giovanni Avolio, Nicola Del Giacomo, Chiara Guido, M. Lazzaro
Published 2008-04-14 by SAE International in United States
In the present paper, the effect of the clean and cold EGR flow on the performance of a diesel engine running under conventional and Low Temperature Combustion conditions is investigated by means of experimental tests on a single-cylinder research engine. The engine layout was “ad hoc” designed to isolate the effect of the clean and cold recirculated gas flow on the combustion quality.The results have shown that the thermodynamic temperature is the main factor affecting the engine performances, while the effect of a cleaner EGR flow, in terms of lower smoke and unburned compounds (HC and CO), is negligible.
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Experimental Analysis of the Operating Parameter Influence on the application of Low Temperature Combustion in the Modern Diesel Engines

Istituto Motori - Consiglio Nazionale delle Ricerche-Carlo Beatrice, Giovanni Avolio, Chiara Guido
Published 2007-07-23 by SAE International in United States
The present paper describes the effects of some operating parameters on the performance of a single cylinder research engine when it runs under Low Temperature Combustion (LTC) conditions.Aim of the experimental work was to explore the potential of the control of each parameter on the improvement of LTC application to the modern LD diesel engines for passenger cars.In particular, the effects on LTC performance of the following operating parameters in different engine test points were analyzed: intake air temperature, exhaust EGR cooler temperature, intake pipe pressure, exhaust pipe pressure and swirl ratio.Some parameters have shown a particular influence on the improvement of EGR tolerability for maximum NOx reduction preserving fuel consumption and smoke, while others have evidenced poor sensitivity.
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