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Impact of Biodiesel on Particle Emissions and DPF Regeneration Management in a Euro5 Automotive Diesel Engine

2012-06-18
Biofuel usage is increasingly expanding thanks to its significant contribution to a well-to-wheel (WTW) reduction of greenhouse gas (GHG) emissions. In addition, stringent emission standards make mandatory the use of Diesel Particulate Filter (DPF) for the particulate emissions control. The different physical properties and chemical composition of biofuels impact the overall engine behaviour. In particular, the PM emissions and the related DPF regeneration strategy are clearly affected by biofuel usage due mainly to its higher oxygen content and lower low heating value (LHV). More specifically, the PM emissions and the related DPF regeneration strategy are clearly affected by biofuel usage due mainly to its higher oxygen content and lower low heating value, respectively. The particle emissions, in fact, are lower mainly because of the higher oxygen content. Subsequently less frequent regenerations are required.
Technical Paper

Influence of Catalyst Performance on Car Emissions in Urban Congested Traffic

1997-05-01
971604
A reason of the lack of agreement between measured pollutants concentration in the air of urban areas and vehicle pollutant emissions evaluated by available emission models is the fact that catalyst performance variability is not considered. In this paper, an experimental study on the effect of performance variability of catalyst on emissions is presented. Average emissions have been measured using driving cycles representative of different levels of urban traffic, determined by statistical methods on the basis of data detected on-road by an instrumented car. For each driving cycle, representative of a certain traffic level, different thermal starting conditions of catalyst have been tested. These conditions have been determined by the characterization of catalyst performance at steady state and are representative of real catalyst conditions experienced on the road.
Technical Paper

Experimental Evaluation of Fuel Consumption and Emissions in Congested Urban Traffic

1995-10-01
952401
In this paper, first results regarding measurements of fuel consumption and emissions, relative to different traffic conditions and a specific urban area, are presented. The experimental approach used for the evaluation of emissions consists in: a) recording on-road car and engine operating conditions during designed trips performed in the center of Naples (Italy) by an instrumented car, b) determining by multivariate statistical analysis driving cycles characterizing typical traffic conditions, c) measuring emissions and fuel consumption in laboratory using defined driving cycles. Fuel flow rate measurements are performed at each second, while emissions are detected along a cycle and an average value per kilometer is obtained. Operating conditions of engine during laboratory testing are related to on-road operating conditions by comparing fuel consumption and exhaust gases temperatures measurements performed on-road and in laboratory by the same device.
Technical Paper

Two Dimensional Analysis of Diesel Combustion by Spectral Flame Emissivity Measurements

1996-02-01
960838
Spectral flame emissivity and absorption measurements with high temporal and spatial resolution were performed in an optically accessible high-swirl divided-chamber Diesel system. Simultaneous determination of soot temperature, soot volume fraction and the OH radical concentration were made from the start to the end of the combustion in 153 locations equally distributed in the chamber. The engine was run at 2000 rpm and at fixed air-fuel ratio realizing 200 consecutive combustion cycles. To visualize the spatial and temporal spray and flame evolution, direct high-speed photographic sequences were taken at 8000 frames/s. The photographic sequences showed that the spray is strongly distorted and mixed by very high swirl resulting in a well premixed region where the combustion starts. The OH radicals were detected in the fuel reaction zone. Moreover OH concentration and soot volume fraction are well correlated with soot temperature.
Technical Paper

An Assessment of Predictivity of CFD Computations of Combustion and Pollutants Formation in D.I. Diesel Engines

1996-10-01
962055
In the present paper the status of development of diesel combustion and pollutants formation modelling at Diesel Engines and Fuels Research Division of Istituto Motori is pointed out. The main features and performances of the model are discussed comparing the numerical results with some experimental data. For the experiments a single cylinder direct injection diesel engine was used. In the head of the engine two small quartz windows have been mounted, in order to obtain pictures of the injection and combustion processes by high speed cinematography, and to apply the two colour technique for soot temperature and soot loading measurements. The soot loading was measured by the two colour technique and the a priori and the experimental uncertainties of the measurement technique were carefully evaluated. In addition, the engine may be also equipped with a second head, in which a fast acting valve allows the direct sampling of the combustion products.
Technical Paper

Three Dimensional Calculations of DI Diesel Engine Combustion and Comparison whit In Cylinder Sampling Valve Data

1992-10-01
922225
A modified version of KIVA II code was used to perform three-dimensional calculations of combustion in a DI diesel engine. Both an ignition delay submodel and a different formulation of the fuel reaction rate were implemented and tested. The experiments were carried out on a single cylinder D.I. diesel of 0.75 I displacement equipped with sensors to detect injection characteristics and indicated pressure. A fast acting sampling valve was also installed in the combustion chamber to allow the measurement of main pollutants during the combustion cycle, by an ensemble average technique. Computational and experimental results are compared and the discrepancies are discussed. Today the demand for light duty engines that produce less emission and consume less fuel is increasing. Thus, if limits on CO2 emissions are established, the direct injection diesel engine for light duty applications will become an attractive option.
Technical Paper

The Influence of Fuel Composition on Particulate Emissions of DI Diesel Engines

1993-10-01
932733
The effect of different fuel parameters on emissions is difficult to understand, the response depending upon different engine technologies. In addition the isolation of some of the fuel variables is often very hard. The present paper discusses the main results obtained testing a matrix of 14 fuels designed for obtain large variations of cetane number, sulphur and aromatic contents of Diesel oil. The aromatic structure of fuels and its effect on particulate emissions was also investigated. A linear regression analysis was performed in order to isolate the main controlling factors on particulate emissions. Finally the influence of aromatic contents of fuel on unregulated emissions was also assessed.
Technical Paper

Soot Formation and Oxidation in a DI Diesel Engine: A Comparison Between Measurements and Three Dimensional Computations

1993-10-01
932658
Three dimensional computations of Diesel combustion were performed using a modified version of Kiva II code. The autoignition and combustion model were tuned on a set of experimental conditions, changing the engine design, the operating conditions and the fuel characteristics. The sensitivity of the model to the different test cases is acceptable and the experimental trends are well reproduced. In addition the peak of pressure and temperature computed by the code are quite close to the experimental values, as well as the pressure derivatives. Once tuned the combustion model constants, different but simple formulations for the soot formation and oxidation processes were implemented in the code and compared with the experimental measurements obtained both with fast sampling technique and two colors method. These formulations were found unable to give good prediction in a large range of engine operating conditions, even if the model tuning may be very good for each test point.
Technical Paper

Ultra-High Speed Fuel Tracer PLIF Imaging in a Heavy-Duty Optical PPC Engine

2018-04-03
2018-01-0904
In order to meet the requirements in the stringent emission regulations, more and more research work has been focused on homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) or partially premixed compression ignition (PCCI) as they have the potential to produce low NOx and soot emissions without adverse effects on engine efficiency. The mixture formation and charge stratification influence the combustion behavior and emissions for PPC/PCCI, significantly. An ultra-high speed burst-mode laser is used to capture the mixture formation process from the start of injection until several CADs after the start of combustion in a single cycle. To the authors’ best knowledge, this is the first time that such a high temporal resolution, i.e. 0.2 CAD, PLIF could be accomplished for imaging of the in-cylinder mixing process. The capability of resolving single cycles allows for the influence of cycle-to-cycle variations to be eliminated.
Technical Paper

Effect of Hydrogen Enrichment on Flame Morphology and Combustion Evolution in a SI Engine Under Lean Burn Conditions

2018-04-03
2018-01-1144
Uncertainty of fuel supply in the energy sector and environmental protection concerns have motivated studies on clean and renewable alternative fuels for vehicles as well as stationary applications. Among all fuel candidates, hydrogen is generally believed to be a promising alternative, with significant potential for a wide range of operating conditions. In this study, a comparison was carried out between CH4, two CH4/H2 blends and two mixtures of CO and H2, the last one taken as a reference composition representative of syngas. It is imperative to fully understand and characterize how these fuels behave in various conditions. In particular, a deep knowledge of how hydrogen concentrations affect the combustion process is necessary, given that it represents a fundamental issue for the optimization of internal combustion engines. To this aim, flame morphology and combustion stability were studied in a SI engine under lean burn conditions.
Technical Paper

Experimental Characterization of an Ethanol DI - Gasoline PFI and Gasoline DI - Gasoline PFI Dual Fuel Small Displacement SI Engine

2015-04-14
2015-01-0848
The aim of the paper is the comparison of the performance, gaseous and particle emissions from different injection configurations and fuels. The engine was operated in port fuel injection (PFI), direct injection (DI) and dual fuel (DF). For DF, ethanol DI-gasoline PFI and gasoline DI-gasoline PFI strategies were performed to discern the effect of injection strategy from the effect of the fuel. The experimental activity was carried out in a small displacement single cylinder engine, representative of 2-3 wheel vehicle engines or of 3-4 cylinder small displacement automotive engines. It was equipped with a prototype gasoline direct injection (GDI) head. The tests were carried out at 3000 rpm, 4000 rpm and 5000 rpm full load. The investigated engine operating conditions are representative of the homologation urban driving cycle. The gaseous and particle emissions were measured at the exhaust by means of a gas analyzer and a smoke meter.
Technical Paper

Modeling Pressure Oscillations under Knocking Conditions: A Partial Differential Wave Equation Approach

2010-10-25
2010-01-2185
In this work the authors present a model to simulate the in-cylinder pressure oscillations due to knock. Pressure oscillations are predicted by the explicit integration of a Partial Differential Wave Equation (PDWE) similar, in its structure, to the so-called “Equation of Telegraphy”. This equation differs mainly from the classical wave formulation for the presence of a loss term. The general solution of such equation is obtained by the Fourier method of variables separation. The integration space is a cylindrical acoustic cavity whose volume is evaluated at the knock onset. The integration constants are derived from the boundary and initial conditions. A novel approach is proposed to derive the initial condition for the derivative of the oscillating component of pressure. It descends, conceptually, from the integration of the linearized relation between the derivative of pressure versus time and the expansion velocity of burned gas.
Technical Paper

Combustion Process Investigation in a Small SI Engine using Optical Diagnostics

2010-10-25
2010-01-2262
Nowadays an elevated number of two, three and four wheels vehicles circulating in the world-wide urban areas is equipped with Port Fuel Injection Spark Ignition (PFI SI) engines. Their technological level is high, but a further optimization is still possible, especially at low engine speed and high load. To this purpose, the scientific community is now focused on deepening the understanding of thermo fluid dynamic phenomena that takes place in this kind of engine: the final purpose is to find key points for the reduction in engine specific fuel consumption and exhaust emissions without a decrease in performance. In this work, the combustion process was investigated in an optically accessible single cylinder PFI SI engine. It was equipped with the head, injection device and exhaust line of a commercial small engine for two-wheel vehicles, it had the same geometrical characteristics in terms of bore, stroke and compression ratio.
Technical Paper

Idle Speed Control of GDI-SI Engines via ECU-1D Engine Co-Simulation

2010-10-25
2010-01-2220
Idle Speed Control plays a crucial role to reduce fuel consumption that turns in both a direct economic benefit for customers and CO\d reduction particularly important to tackle the progressive global environmental warming. Typically, control strategies available in the automotive literature solve the idle speed control problem acting both on the throttle position and the spark advance, while the Air-Fuel Ratio (AFR), that strongly affects the indicated engine torque, is kept at the stoichiometric value for the sake of emission reduction. Gasoline Direct Injection (GDI) engines, working lean and equipped with proper mechanisms to reduce NOx emissions, overcome this limitation allowing the AFR to be used for the idle speed regulation.
Technical Paper

Assessment of Closed-Loop Combustion Control Capability for Biodiesel Blending Detection and Combustion Impact Mitigation for an Euro5 Automotive Diesel Engine

2011-04-12
2011-01-1193
The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori - CNR aimed at studying the impact of both fresh and highly oxidized Rapeseed Methyl Ester (RME) at different levels of blending on performance, emissions and fuel consumption of modern automotive diesel engines featuring Closed-Loop Combustion Control (CLCC). In parallel, the capability of this system to detect the level of biodiesel blending through the use of specific detection algorithms was assessed. The tests were performed on the recently released 2.0L Euro5 GM diesel engine for passenger car application equipped with embedded pressure sensors in the glow plugs. Various blends of fresh and aged RME with reference diesel fuel were tested, notably 20% RME by volume (B20), 50% (B50) and pure RME (B100).
Technical Paper

Multiple Injection in a Mixed Mode GDI Boosted Engine

2010-05-05
2010-01-1496
A numerical investigation is performed with the aim of understanding the potential benefits of multiple injections in the mixed mode boosting operation of a Gasoline Direct Injection (GDI) engine. The study is carried out by firstly characterizing a high pressure multi-hole injector from the experimental point of view in the split injection operation. Measurements of the fuel injection rate are made through an AVL Meter operating on the Bosch principle. The injector is tested using gasoline in a double pulse strategy. The injection pressure is varied between 5.0 and 25.0 MPa with the pulse durations calibrated for delivering a total mass up to 50 mg/str. The choice of the dwell time between two successive injection events is achieved by firstly defining the minimum time compatible with the mechanical characteristics of both the injector and the injector driver.
Technical Paper

Combustion Analysis in an Optical Diesel Engine Operating with Low Compression Ratio and Biodiesel Fuels

2010-04-12
2010-01-0865
In this paper we report how optical techniques were applied in the cylinder of an optically accessible engine equipped with latest-generation EURO V diesel engine head. The injection strategy with high percentage of EGR, characteristic of real engine operating point, was adopted. In particular, the combustion behavior at 1500 rpm\2 bar BMEP was investigated. Alternative diesel fuels were used. In particular, rapeseed methyl ester (RME) and gas to liquid (GTL) were selected as representative of 1st and 2nd generation alternative diesel fuel, respectively. Combustion analysis was carried out in the engine combustion chamber by means of visible digital imaging. These measurements helped to analyze the chemical and physical events occurring during the mixture preparation and the combustion development. Ultraviolet (UV) digital imaging was also performed and the presence of characteristic radical, like OH, in the various phases of combustion was detected as well.
Technical Paper

Fuel Injection Effect on In-cylinder Formation and Exhaust Emission of Particulate from a 4-Stroke Engine for 2-Wheel Vehicles

2010-04-12
2010-01-0354
The small engine for two-wheel vehicles has generally high possibility to be optimized at low speeds and high loads. In these conditions fuel consumption and pollutants emission should be reduced maintaining the performance levels. This optimization can be realized only improving the basic knowledge of the thermo-fluid dynamic phenomena occurring during the combustion process. It is known that, during the fuel injection phase in PFI SI engines, thin films of liquid fuel can form on the valves surface and on the cylinder walls. Successively the fuel films interact with the intake manifold and the combustion chamber gas flow. During the normal combustion process, it is possible to achieve gas temperature and mixture strength conditions that lead to fuel film ignition. This phenomenon can create diffusion-controlled flames that can persist well after the normal combustion event. These flames induce the emission of soot and unburned hydrocarbons.
Technical Paper

Effects of Low Temperature Premixed Combustion (LTPC) on Emissions of a Modern Diesel Engine for Passenger Cars

2010-04-12
2010-01-0333
In this paper, a Low Temperature Premixed Combustion (LTPC) was investigated employing a four cylinder D.I. common rail Diesel engine, used for passenger cars on the European market. Experiments were carried out setting the engine speed at 2500 rpm with a fuel amount of 26 mg/str to realize an operating condition close to the point of NEDC at 0.8 MPa of BMEP. The experimental approach was the management of the start of injection, injection pressure and EGR rates as a method to control NOx and soot production. The investigation was first carried out testing engine performances and emissions as set from the commercial engine map. Afterward, engine tests were carried out exploring performances, gaseous and smoke emissions at late start of combustion [10 to 17.5 cad ATDC], injection pressures from 80 to 120 MPa and EGR rates up to 50%.
Technical Paper

Influence of Driving Cycles on Powered Two-Wheelers Emissions, Fuel Consumption and Cold Start Behavior

2013-04-08
2013-01-1048
A wide investigation on powered two-wheelers (PTWs) is presented, aiming at the analysis of the influence of the driving characteristics on PTWs exhaust emissions and fuel consumption, a deeper comprehension of the engine and after-treatment system behavior within the cold start transient and the evaluation of cold start additional emissions for different two-wheelers classes. The study was developed with reference to an European context focusing on Euro 3 motorcycles and Euro 2 mopeds. An experimental investigation on instantaneous speed measurements was carried out with instrumented motorcycles, considering typical urban trips in the city of Genoa. A selection of speed profiles was then performed by processing experimental values.
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