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Effects of Prechamber on Efficiency Improvement and Emissions Reduction of a SI Engine Fuelled with Gasoline

Istituto Motori CNR-Paolo Sementa, Francesco Catapano, Silvana Di Iorio, Bianca Maria Vaglieco
Published 2019-10-07 by SAE International in United States
The permanent aim of the automotive industry is the further improvement of the engine efficiency and the simultaneous pollutant emissions reduction.The aim of the study was the optimization of the gasoline combustion by means of a passive prechamber. This analysis allowed the improvement of the engine efficiency in lean-burn operation condition too. The investigation was carried out in a commercial small Spark Ignition (SI) engine fueled with gasoline and equipped with a proper designed passive prechamber.It was analyzed the effects of the prechamber on engine performance, Indicated Mean Effective Pressure, Heat Release Rate and Fuel Consumption were used. Gaseous emissions were measured as well. Particulate Mass, Number and Size Distributions were analyzed. Emissions samples were taken from the exhaust flow, just downstream of the valves. Four different engine speeds were investigated, namely 2000, 3000, 4000 and 5000 rpm. Stoichiometric and lean conditions at full load were considered in all tests. The results were compared with those obtained with the engine equipped with the standard spark plug. The results indicated that both performance and emissions were…
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Analysis of the Impact of the WLTP Procedure on CO2 Emissions of Passenger Cars

European Commission Joint Research-Biagio Ciuffo, Georgios Fontaras
Politecnico di Torino-Giuseppe DiPierro, Federico Millo, Claudio Cubito
Published 2019-10-07 by SAE International in United States
Until 2017 in Europe the Type Approval (TA) procedure for light duty vehicles for the determination of pollutant emissions and fuel consumption was based on the New European Driving Cycle (NEDC), a test cycle performed on a chassis dynamometer. However several studies highlighted significant discrepancies in terms of CO2 emissions between the TA test and the real world, due to the limited representativeness of the test procedure. Therefore, the European authorities decided to introduce a new, up-to date, test procedure capable to closer represent real world driving conditions, called Worldwide Harmonized Light Vehicles Test Procedure (WLTP). This work aims to analyze the effects of the new WLTP on vehicle CO2 emissions through both experimental and simulation investigations on two different Euro 5 vehicles, a petrol and a diesel car, representatives of average European passenger cars. The study also considers the effect of the engine warm-up and the impact of the start-stop technology in this new TA scenario. Since the WLTP imposes higher test mass and Road Loads (RLs), as well as higher driving cycle dynamics,…
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Knock Onset Detection Methods Evaluation by In-Cylinder Direct Observation

Istituto Motori CNR-Francesco Catapano, Paolo Sementa, Bianca Maria Vaglieco
Published 2019-10-07 by SAE International in United States
Improvement of performance and emission of future internal combustion engine for passenger cars is mandatory during the transition period toward their substitution with electric propulsion systems. In middle time, direct injection spark ignition (DISI) engines could offer a good compromise between fuel economy and exhaust emissions. However, abnormal combustion and particularly knock and super-knock are some of the most important obstacles to the improvement of SI engines efficiency. Although knock has been studied for many years and its basic characteristics are clear, phenomena involved in its occurrence are very complex and are still worth of investigation. In particular, the definition of an absolute knock intensity and the precise determination of the knock onset are arduous and many indexes and methodologies has been proposed.In this work, most used methods for knock onset detection from in- cylinder pressure signal have been considered. Moreover, knock intensity has been evaluated by means of two common indexes. High speed imaging has been carried out in the combustion chamber of a high performance DISI engine provided with an optical window in…
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How to Improve SI Engine Performances by Means of Supercritical Water Injection

University of Basilicata – Potenza 85100-Antonio Cantiani, Annarita Viggiano, Vinicio Magi
Published 2019-10-07 by SAE International in United States
The efficiency of ICEs is strongly affected by exhaust gases and engine cooling system heat losses, which account for about 50% of the heat released by combustion. A promising approach is to transfer this exhaust heat to a fluid, like water, and inject it into the combustion chamber under supercritical conditions. In such a way, the recovered energy is partially converted into mechanical work, improving both engine efficiency and performance.A quasi-dimensional model has been implemented to simulate an SI engine with supercritical water injection. Specifically, a spark ignition ICE, four-stroke with Port Fuel Injection (PFI) has been considered. The model accounts for gas species properties, includes valves opening/closing, wall heat transfer, a water injection model and a combustion model. The influence of some injection parameters, i.e. Water/Fuel ratio (W/F), Start Of water Injection (SOI) and Water Injection Duration (WID), on engine performances and efficiency is discussed in details.The results show that an increase of W/F ratio has the strongest impact on the performances with respect to SOI and WID, i.e. higher W/F ratio, SOI closer…
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Fundamental Concepts of Turbocharging Modern Engines Current Practices and Trends Web Seminar RePlay

  • Webinar Recordings
  • PD331858
Published 2019-09-19
Turbocharging is an integral part of many internal combustion engine systems. While it has long been a key to diesel engine performance, turbocharging is increasingly seen as an enabler in meeting many of the efficiency and performance requirements of modern automotive gasoline engines. This replay discusses the basic concepts of turbocharging and air flow management of four-stroke engines. It explores the fundamentals of turbocharging, system design features, performance measures, and matching and selection criteria. Topics include spark ignition and diesel engine systems, the impact of different applications. The course also covers the interaction between turbocharging and engine systems and the impact on performance, fuel economy, and emissions. Developments in turbocharging technology are also covered.By participating in this course, you will be able to: Identify the basics of how a turbocharger works, how to measure the appropriateness of a turbocharger, and how to select and match a turbocharger to the needs of your powertrainEstimate the impact of turbocharging on performance and emissionsRecognize potential issues such as packaging, noise, driveability, reliability, and durabilityList the latest developments in…
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Injection Pattern Investigation for Gasoline Partially Premixed Combustion Analysis

Magneti Marelli SpA - Powertrain-Federico Stola, Matteo De Cesare
University of Bologna-Vittorio Ravaglioli, Giacomo Silvagni, Fabrizio Ponti
Published 2019-09-09 by SAE International in United States
Nowadays, compression-ignited engines are considered the most efficient and reliable technology for automotive applications. However, mainly due to the current emission regulations, that require increasingly stringent reductions of NOx and particulate matter, the use of diesel-like fuels is becoming a critical issue. For this reason, a large amount of research and experimentation is being carried out to investigate innovative combustion techniques suitable to simultaneously mitigate the production of NOx and soot, while improving engine efficiency.In this scenario, the combined use of compression-ignited engines and gasoline-like fuels proved to be very promising, especially in case the fuel is directly-injected in the combustion chamber at high pressure. The presented study analyzes the combustion process produced by the direct injection of small amounts of gasoline in a compression-ignited light-duty engine. The engine under investigation has been modified to guarantee a stable engine operation over its whole operating range, that is achieved controlling boost pressure and temperature, together with the design of the injection pattern.Experimental tests have been performed to highlight the impact of several control variables on the…
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Performance and Emissions of an Advanced Multi-Cylinder SI Engine Operating in Ultra-Lean Conditions

Renault SA-Cédric LIBERT
University of Naples “Federico II”-Fabio Bozza, Daniela Tufano, Enrica Malfi, Luigi Teodosio, Vincenzo De Bellis
Published 2019-09-09 by SAE International in United States
In this work the performance and noxious emissions of a prototype Spark Ignition (SI) engine, working in ultra-lean conditions, are investigated. It is a four-cylinder engine, having a very high compression ratio, and an active pre-chamber. The required amount of air is provided by a low-pressure variable geometry turbocharger, coupled to a high-pressure E-compressor. The engine is equipped with a variable valve timing device on the intake camshaft.The goal of this activity is to support the development and the calibration of the described engine, and to exploit the full potential of the ultra-lean concept. To this aim, a combustion model for a pre-chamber engine, set up and validated in a previous paper for a similar single-cylinder unit, is utilized. It is coupled to additional in-house developed sub-models, employed for the prediction of the in-cylinder turbulence, heat transfer, knock and pollutant emissions.Such a complex architecture, schematized in a commercial 1D modeling framework, presents several control parameters which have to be properly selected to maximize the engine efficiency and minimize the noxious emissions over its whole operating…
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Influence of Injection Strategies on Engine Efficiency for a Methanol PPC Engine

Lund University-Erik Svensson, Martin Tuner, Sebastian Verhelst
Published 2019-09-09 by SAE International in United States
Partially premixed combustion (PPC) is one of several advanced combustion concepts for the conventional diesel engine. PPC uses a separation between end of fuel injection and start of combustion, also called ignition dwell, to increase the mixing of fuel and oxidizer. This has been shown to be beneficial for simultaneously reducing harmful emissions and fuel consumption. The ignition dwell can be increased by means of exhaust gas recirculation or lower intake temperature. However, the most effective means is to use a fuel with high research octane number (RON). Methanol has a RON of 109 and a recent study found that methanol can be used effectively in PPC mode, with multiple injections, to yield high brake efficiency. However, the early start of injection (SOI) timings in this study were noted as a potential issue due to increased combustion sensitivity. Therefore, the present study attempts to quantify the changes in engine performance for different injection strategies. Simulations were performed on a heavy-duty multi-cylinder compression ignition engine fueled with methanol. Two operating conditions with different engine load were…
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Multi-Level Modeling of Real Syngas Combustion in a Spark Ignition Engine and Experimental Validation

C.M.D. S.p.A.-Domenico Cirillo
CNR Istituto Motori-Michela Costa, Gabriele Di Blasio, Daniele Piazzullo
Published 2019-09-09 by SAE International in United States
Syngas produced from biomass gasification is being increasingly considered as a promising alternative to traditional fuels in Spark-Ignition (SI) Internal Combustion Engines (ICEs). Due to the low energy density and extreme variability in the composition of this gaseous fuel, numerical modeling can give an important contribution to assure stable engine performances.The present work intends to give a contribution in this sense in this sense, by proposing a multi-level set of approaches, characterized by an increasing detail, as a tool aimed at the optimization of energy conversion of non-conventional fuels.At first, a specific characterization of the dependency of the syngas laminar flame speed upon its composition is achieved through an iterative approach pursued in the ANSYS ChemkinTM environment, where validated correlations of the flame speed tuning parameters are obtained in a zero-dimensional framework.Subsequently, the interaction between combustion kinetics and fluid dynamics is considered through the development of a mono-dimensional (1D) model of the whole engine system in the GT-Power environment. A predictive combustion model, tuned on the ground of the combustion parameters determined through the previous…
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A Proposed Diesel Powertrain to Meet Future Emission Standards and Achieve High Engine Efficiency

FPT Motorenforschung AG-Konstantinos Priftis, Apostolos Karvountzis Kontakiotis, Wolfgang Gstrein, Christoph Schuette
Published 2019-09-09 by SAE International in United States
Nowadays, powertrain development activity is performed on the base of fulfilling the stricter emission standards under real driving conditions (RDE). However, the pressure on automotive industry to reduce CO2 emissions in high efficient diesel applications results in lower exhaust gas temperatures. Therefore, it is highly needed to develop advanced vehicle thermal management methods to both fulfil the targets of emission standards and high thermal efficiency, without increasing dramatically the powertrain cost. The aim of this work is to experimentally demonstrate that by utilizing advanced engine and ATS control methods and revising the engine hardware and subsystems can lead to significant improvement on the fuel efficiency and emissions of the conventional diesel powertrain. The revised engine includes an improved combustion system, completely revised turbocharging and air handling system whilst being heavily reworked with respect to FMEP reduction. The aftertreatment employs a closed coupled electrically heated DOC, SCR on filter with an NH3 slip catalyst followed by an underfloor SCR and NH3 slip catalyst. The urea dosing system is utilizing double urea injection to maximize the overall…
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