Search

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 been developed and equipped with, a state-of-the-art Euro 6 combustion system, and an advanced common rail fuel injection system (FIS) offering higher flexibility in terms of injection strategy and higher quantity accuracy. Three injector nozzles with different hydraulic flow rates (HF) have been selected and employed for the overall combustion process optimization. The optimization has been performed by means of an extensive DoE-based test campaign in which the engine and FIS operating parameters have been parametrized with the aim to carry out a proper combination in terms of HF and injection strategy. The results at partial load conditions evidence significant advantages in applying an advanced injection pattern, while the HF reduction can significantly improve the smoke emission and combustion noise without fuel consumption penalties. Therefore, a proper combination and optimization of the HF and injection strategy can provide low noise and engine-out smoke while maintaining the rated power performance targets.

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 single-cylinder engine on which an advanced and last generation common rail system, capable of very high injection pressure, has been installed. Through an extensive DoE-based test campaign in which all engine operating parameters have been carefully parametrized, the capability to achieve high power density and excellent fuel economy with low engine-out pollutant emissions has been demonstrated and discussed in the paper.

In the Paris Climate Agreement of 2015, the not-to-exceed limit of 2 °C global warming until 2050 was defined and in Katowice, 2018, measures were agreed how to control the activities of participating nations. To meet the mentioned target of global warming limitation, worldwide CO2 emitting processes must be improved in all industry and life sectors. Hence, transport industry and therefore propulsion systems of passenger cars and trucks must reduce their CO2 emissions as well. The European Union just recently defined the CO2 reduction targets to 15% and 37.5% for 2025 and 2030, respectively, for passenger cars (based on the 2021 CO2 emissions value for 100 km driving distance).

Synthetische Kraftstoffe, nachhaltig aus Sonnenergie hergestellt, werden zurzeit vielfaltig diskutiert. Bei einer Well-to-Wheel CO2 Bilanzierung (WtW-CO2) ergeben sich hier keine oder nur sehr geringe CO2 Emissionen, da nur das im Herstellungsprozess chemisch gebundene CO2 bei der Nutzung in Verbrennungsmotoren wieder freigesetzt wird.

In order to meet the target of not to exceed the 2°C in global warming until 2050, worldwide CO2 emitting processes have to be improved. Hence, transport industry and therefore propulsion systems of passenger cars and trucks have to reduce their CO2 emissions significantly, also having in mind that the overall number of vehicles will increase in the next three decades by app. 100%.

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 discusses the engine power and efficiency sensitivities to the boundary conditions of the charging/exhaust systems, the fuel injection pressure and the mechanical base engine design (with particular reference to the pfp). Eventually, a balanced set of targets for the entire system based on such results are carried out.

Bekanntlich spielt bei der dieselmotorischen Gemischbildung und Verbrennung neben der zeit- und mengengenauen Dosierung des einzuspritzenden Kraftstoffes, dessen zeitund ortsgenaue lokale Mischung mit der Luft im Brennraum eine entscheidende Rolle fur Verbrauch, Emissionen und Gerausch. Insbesondere bei hoheren Lasten ist die Anhebung der Strahlkraft ein probates Mittel um eine intensivere Durchmischung im Strahl und eine bessere Umlenkung des Brenngases an der Kolbenmulde fur eine gute Luftausnutzung zu erzielen. Die Strahlkraft am Spritzlochaustritt steigt bei gegebenem Spritzlochquerschnitt mit dem Dusenwirkungsgrad (Verhaltnis aus realem zu theoretischem Durchfluss laut Bernoulli) und dem Sacklochdruck, der wiederrum uber Drosseln (Dusensitz, Injektor) in hohem Mase mit dem Raildruck kommuniziert. Basisuntersuchungen zum Einfluss des Wirkungsgrades auf die Verbrennung sind in /1/ erfolgt.

Eine der wesentlichen aktuellen Aufgaben der Automobilindustrie ist die Umsetzung der gesetzlichen Vorgaben, den CO2 Ausstos ihrer Fahrzeugflotten zu verringern. Die Herausforderung ist umso groser, da der weltweite Trend zu groseren Fahrzeugen mit hoherem Gewicht ungebrochen ist, siehe Bild 1: Fur das Jahr 2023 wird erwartet, dass uber 75 % der sogenannten Light Vehicles (bis 6 Tonnen) schwerer als 1,2 Tonnen sind.

Evaluating the dependability of large-scale critical infrastructures is a very difficult task that requires sophisticated modeling practices and experimentation environments/infrastructures. In particular, simulation of complex distributed systems require the integration of several different simulation tools and real-time prototypes or emulated subsystems, which have to inter-operate in a coordinated way. This paper presents a framework integrating simulation and emulation-based subsystems, which is able to provide greater realism of the scenario under test. However, integrating simulation and emulation is a challenging issue because of the different time domains and to the communication overhead between the different time models, as well as to the large number of involved entities. Therefore, the high level architecture has been used to perform integration in a robust and standardized scenario. A cloud-based virtualization platform has been adopted in order to reproduce complex system architectures on an elastic and adaptive locally controlled testbed. Copyright © 2015John Wiley & Sons, Ltd.

The distributed and complexity nature of modern critical infrastructures that have to provide integrated services through the interoperability of heterogeneous subsystems, even spread among different countries, require new methodologies and tools to dominate overall systems complexity. In particular, in order to get knowledge about their real behavior and define dependability improvement actions, such complex and distributed systems should be reproduced and simulated locally. On the other hand, the extraordinary large number of their components cause a large-scale of the resulting model, limiting its resolution by current simulators. This paper presents a framework to implement hybrid simulation of distributed large-scale critical infrastructures, such as Air Traffic Control (ATC) and Vessel Traffic System (VTS). High Level Architecture (HLA) has been introduced into the engine simulations platform as its design and development foundation, whereas cloud-based virtualization techniques have been exploited in order to reproduce the overall distributed system on a local adaptive testbed. The use of such a framework can result in a considerable reduction of costs in all the system life phases, as well as an increased system dependability level.

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 engine operating conditions typical of diesel engine operating. Main deliverables of the above mentioned activity will be guidelines for a balanced nozzle flow number selection and references for upgrading 3D-CFD simulations spray models. Spatial and temporal spray characterizations have been evaluated for three different nozzle flow numbers for a 2.0L diesel engine in various operating conditions. The results confirm that by reducing the flow number, for low injected quantities typical of low load and speed engine conditions, better fuel/air mixing is achieved. On the contrary, increasing the injected quantity (as for medium/high load and speed conditions) flow number reduction requires engine recalibration in order to keep the advantages of mixture formation.

In the present paper, the effect of the clean and cold EGR flow on the performance of a diesel engine running under 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 the possibility to increase the EGR rate by EGR flow temperature reduction, with a decrement of both NOx and PM emissions, at the same fuel consumption, highlighting that the intake manifold temperature is the main factor affecting the engine performances.

The present paper is focused on the application of the Low Temperature Combustion (LTC) systems to modern diesel engines. Aim of the work was to assess the possibility to optimize LTC systems performances in terms of both engine efficiency and pollutant emissions. In particular, the results of a study of the effects of highly cooled Exhaust Gas Recirculation (EGR) on a diesel engine running at LTC condition, will be presented and discussed. The engine employed for the experimental activity was a FIAT JTD 4-cylinder CR diesel engine, EURO 4 version. The EGR layout was modified with respect to the production one, in order to obtain lower temperatures of the recirculated exhaust gases. The performed tests evidence the advantages offered by the strong EGR cooling (and so the lower intake air temperature) in reducing NOx emissions, leaving very low soot emissions, typical of premixed low temperature combustion. The results suggest the possibility to improve the EGR cooling system of the production engines or to arrange a "long route" EGR system in order to improve the engine emission performance.

International audience; The present paper describes one of the Low Temperature Combustion (LTC) management philosophies, today under development for application to Diesel engines, showing and analysing some critical aspects deriving from its use. In particular, starting from the analysis of the application of LTC to a four-cylinder Diesel engine, at the state of the art of current technology, the emission performance for LTC and conventional Diesel combustion are compared, together with the constraint in the application of LTC to the limited low load-low speed range. Moreover, the problems relative to different air/fuel feeding for each cylinder, knocking, torque drop and high smoking event during transient conditions, different actuation velocity of the components (of injection, turbo, EGR and swirl control systems) during the switch between LTC and conventional combustion, are presented and critically commented, indicating the main research drivelines for practical application.

The present paper describes the effects of some air-path operating parameters on the performance of a modern common-rail diesel 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 order to meet future NOx emissions limits avoiding penalties in fuel consumption and drivability. In particular, the effects on LTC performance of the following operating parameters were analysed: intake air temperature, exhaust EGR cooler temperature, intake pipe pressure, exhaust pipe pressure and swirl ratio. Tests are carried out with a single-cylinder research diesel engine derived from FIAT 1.9 JTD 16V Multi-Jet in the EURO4 version. Results analysis have shown a significant influence of some examined parameters on the improvement of EGR tolerability, that has led to sensitive NOx reduction, within fixed limits in fuel consumption and smoke. On the contrary, engine behaviour is insensitive to the variation of the other air-path parameters.Copyright © 2007 by ASME

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.

Aim of the present paper was an evaluation of the importance of some engine parameters (intake gas flow and injection parameters) on the approach of Premixed Low Temperature Combustion (PLTC) conditions with the same efficiency of a conventional diesel cycle and ultra-low pollutant emissions. The results have demonstrated that the control of PLTC mode is very difficult and the engine parameters play a critical role on the exhaust pollutant emissions, indicating that further massive research activities are needed to reach reliable practical applications.

The present paper describes an experimental study on the effect of the nozzle flow number (FN) on the full load performance of a modern Euro5 diesel automotive engine, in terms of torque, efficiency and exhaust emissions.