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Technical Paper

Experimental Analysis of the Operating Parameter Influence on the application of Low Temperature Combustion in the Modern Diesel Engines

2007-07-23
2007-01-1839
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.
Technical Paper

Evaporating Diesel Spray Visualization using a Double-pass Shadowgraphy/Schlieren imaging

2007-09-16
2007-24-0026
Evaporating diesel sprays from multi-hole nozzles have been visualized by means of a double-pass Shadowgraphy/Schlieren technique using a metal mirror attached on the injector-mount plane. Injection has been carried out in an inert environment of nitrogen gas in order to study the mixture process, avoiding mirror and glass window fouling by soot deposition from combustion. Studies have been carried out for four different gas densities during spray injection, changing pressure and temperature. The effect of optical system alignment on image characteristics has been analysed for different beam angles relative to the optical axis. This parameter was varied in a range of 2 degrees to define the optimal optical configuration. If the angle equals 0, the Shadowgraphy/Schlieren system using a light reception back from the metallic mirror captures the spatial gradients of ambient gas density, and turbulent flow structures are clearly registered.
Technical Paper

Influence of the Post-Injection Pattern on Performance, Soot and NOx Emissions in a HD Diesel Engine

2002-03-04
2002-01-0502
The main objective of the study described in this paper is to explore the potential of different post-injection patterns, with a plain common rail system, for reduction of soot emissions in HD diesel engines. Test have been carried out in a single-cylinder engine at several critical engine operation points from the European Steady state test Cycle (ESC). At these operation points, EGR was introduced to reduce NOx emissions to a given value, and then different post-injection patterns were produced. A parametric study was performed, considering the time between injections and the post-injected fuel mass as the main variables. In every case the total injected fuel mass was kept constant. Aside from the experimental data obtained in the engine tests, a diagnosis model was applied to calculate heat release laws and other parameters depicting the combustion process.
Technical Paper

Compression Ratio Influence on the Performance of an Advanced Single-Cylinder Diesel Engine Operating in Conventional and Low Temperature Combustion Mode

2008-06-23
2008-01-1678
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.
Technical Paper

The Effect of “Clean and Cold” EGR on the Improvement of Low Temperature Combustion Performance in a Single Cylinder Research Diesel Engine

2008-04-14
2008-01-0650
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.
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

Effect of Port Injected Ethanol on Combustion Characteristics in a Dual-Fuel Light Duty Diesel Engine

2013-04-08
2013-01-1692
Nowadays, alcoholic fuels gain increased interest as alternative transportation biofuel even in compression ignition engines due to the fact that they contain oxygen and can be produced in a sustainable way. Furthermore, due to their lower CN (Cetane Number) they suit better for premixed combustion applications. Experimental research was conducted on a single cylinder engine provided with modern engine architecture modified for DF (Dual-Fuel) purposes. The authors have investigated the use of ethanol in a DF engine in order to exploit its well-known advantages in premixed combustion mode. The DF approach appears to be a promising solution because it permits flexible control of the premixed fuel fraction regardless from the operating conditions. This improves the exploitation of the ethanol potential according the engine working conditions.
Technical Paper

Combustion and Emission Characteristics of a Diesel Engine Fuelled with Diesel-LPG Blends

2019-09-09
2019-24-0038
Recently, it has been worth pointing out the relevance of alternative fuels in the improvement of air quality conditions and in the mitigation of global warming. In order to deal with these demands, in recent studies, it has been considered a great variety of alternative fuels. It goes without saying that the alternative fuels industry needs the best of the efficiency with a moderate layout. From this perspective, Liquefied Petroleum Gas (LPG) could represent a valid option, although it is not a renewable fuel. In terms of polluting emissions, the LPG can reduce nitrous oxides and smoke concentrations in the air, a capability that has a relevant importance for the modern pollution legislation. LPG is well known as an alternative fuel for Spark Ignition (SI) engines and, more recently, LPG systems have also been introduced in the Compression Ignition (CI) engines in dual-fuel configuration.
Technical Paper

Soot Characterization of Diesel/Gasoline Blends Injected through a Single Injection System in CI engines

2017-09-04
2017-24-0048
In the past few years’ various studies have shown how the application of a highly premixed dual fuel combustion for CI engines leads a strong reduction for both pollutant emissions and fuel consumption. In particular a drastic soot and NOx reduction were achieved. In spite of the most common strategy for dual fueling has been represented by using two different injection systems, various authors are considering the advantages of using a single injection system to directly inject blends in the chamber. In this scenario, a characterization of the behavior of such dual-fuel blend spray became necessary, both in terms of inert and reactive ambient conditions. In this work, a light extinction imaging (LEI) has been performed in order to obtain two-dimensional soot distribution information within a spray flame of different diesel/gasoline commercial fuel blends. All the measurements were conducted in an optically accessible two-stroke engine equipped with a single-hole injector.
Technical Paper

Parametric Analysis of the Effect of Pilot Quantity, Combustion Phasing and EGR on Efficiencies of a Gasoline PPC Light-Duty Engine

2017-09-04
2017-24-0084
In this paper, a parametric analysis on the main engine calibration parameters applied on gasoline Partially Premixed Combustion (PPC) is performed. Theoretically, the PPC concept permits to improve both the engine efficiencies and the NOx-soot trade-off simultaneously compared to the conventional diesel combustion. This work is based on the design of experiments (DoE), statistical approach, and investigates on the engine calibration parameters that might affect the efficiencies and the emissions of a gasoline PPC. The full factorial DoE analysis based on three levels and three factors (33 factorial design) is performed at three engine operating conditions of the Worldwide harmonized Light vehicles Test Cycles (WLTC). The pilot quantity (Qpil), the crank angle position when 50% of the total heat is released (CA50), and the exhaust gas recirculation (EGR) factors are considered. The goal is to identify an engine calibration with high efficiency and low emissions.
Technical Paper

How Much Regeneration Events Influence Particle Emissions of DPF-Equipped Vehicles?

2017-09-04
2017-24-0144
Diesel particulate filter (DPF) is the most effective emission control device for reducing particle emissions (both mass, PM, and number, PN) from diesel engines, however many studies reported elevated emissions of nanoparticles (<50 nm) during its regeneration. In this paper the results of an extensive literature survey is presented. During DPF active regeneration, most of the literature studies showed an increase in the number of the emitted nanoparticles of about 2-3 orders of magnitude compared to the normal operating conditions. Many factors could influence their amount, size distribution, chemical-physical nature (volatiles, semi-volatiles, solid) and the duration of the regenerative event: i.e. DPF load and thermodynamic conditions, lube and fuel sulfur content, engine operative conditions, PN sampling and measurement methodologies.
Technical Paper

An Experimental Investigation on Spray Mixing and Combustion Characteristics for Spray C/D Nozzles in a Constant Pressure Vessel

2018-09-10
2018-01-1783
The Engine Combustion Network (ECN) is a coordinate effort from research partners from all over the world which aims at creating a large experimental database to validate CFD calculations. Two injectors from ECN, namely Spray C and D, have been compared in a constant pressure flow vessel, which enables a field of view of more than 100 mm. Both nozzles have been designed with similar flow metrics, with Spray D having a convergent hole shape and Spray C a cylindrical one, the latter being therefore more prone to cavitation. Although the focus of the study is on reacting conditions, some inert cases have also been measured. High speed schlieren imaging, OH* chemiluminescence visualization and head-on broadband luminosity have been used as combustion diagnostics to evaluate ignition delay, lift off length and reacting tip penetration. Parametric variations include ambient temperature, oxygen content and injection pressure variations.
Technical Paper

The Key Role of Advanced, Flexible Fuel Injection Systems to Match the Future CO2 Targets in an Ultra-Light Mid-Size Diesel Engine

2018-05-30
2018-37-0005
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.
Technical Paper

Outwardly Opening Hollow-Cone Diesel Spray Characterization under Different Ambient Conditions

2018-09-10
2018-01-1694
The combustion quality in modern diesel engines depends strictly on the quality of the air-fuel mixing and, in turn, from the quality of spray atomization process. So air-fuel mixing is strongly influenced by the injection pressure, geometry of the nozzle duct and the hydraulic characteristics of the injector. In this context, spray concepts alternative to the conventional multi-hole nozzles could be considered as solutions to the extremely high injection pressure increase to assure a higher and faster fuel-air mixing in the piston bowl, with the final target of increasing the fuel efficiency and reducing the engine emissions. The study concerns an experimental depiction of a spray generated through a prototype high-pressure hollow-cone nozzle, under evaporative and non-evaporative conditions, injecting the fuel in a constant-volume combustion vessel controlled in pressure and temperature up to engine-like gas densities in order to measure the spatial and temporal fuel patterns.
Technical Paper

The Influence of Injection Parameters on Diesel Spray Characteristics

1999-03-01
1999-01-0200
This paper has the objective of characterising the macro and microscopic behaviour of Diesel sprays generated by a common-rail system and quantifying the influence of injection parameters and boundary conditions through a broad experimental study. The main purpose of this research is to validate and extend the different correlations available in the literature to the case of sprays generated by common-rail systems, i.e. at high injection pressures with small nozzle holes. The sprays are characterised in an environment which simulates the in-cylinder air density existing in the real engine when the injection starts. However, it should be pointed out that isothermal conditions at room temperature are considered and very little evaporation occurs.
Technical Paper

Assessment of Engine Control Parameters Effect to Minimize GHG Emissions in a Dual Fuel NG/Diesel Light Duty Engine

2018-04-03
2018-01-0266
The interest in Natural Gas (NG) as alternative fuel for transportation is constantly growing, mostly due to its large availability and lower environmental impact with respect to gasoline or diesel fuel. In this scenario, the application of the Dual Fuel (DF) Diesel- Natural Gas (NG) combustion concept to light duty engines can represent an important route to increment the diffusion of natural gas use. Many studies have proven the benefits of DF with respect to conventional diesel combustion in terms of CO2, NOx, PM and PN emissions, with the main drawback of high unburned hydrocarbon, mainly at low/partial engine loads. This last aspect still prevents the application of DF mode to small displacement engines. In the present work, a 2.0 L Euro 5 compliant diesel engine, equipped with an advanced electronic closed-loop combustion control (CLCC) system, has been set up to operate in DF mode and tested on a dyno test bench.
Technical Paper

Evaluation of Vortex Center Location Algorithms for Particle Image Velocimetry Data in an Optical Light-Duty Compression Ignition Engine

2018-04-03
2018-01-0209
Ever decreasing permitted emission levels and the necessity of more efficient engines demand a better understanding of in-cylinder phenomena. In swirl-supported compression ignition (CI) engines, mean in-cylinder flow structures formed during the intake stroke deeply influence mixture preparation prior to combustion, heat transfer and pollutant oxidation all of which could potentially improve engine performance. Therefore, the ability to characterize these mean flow structures is relevant for achieving performance improvements. CI mean flow structure is mainly described by a precessing vortex. The location of the vortex center is key for the characterization of the flow structure. Consequently, this work aims at evaluating algorithms that allow for the location of the vortex center both, in ensemble-averaged velocity fields and in instantaneous velocity fields.
Journal Article

Functional Requirements to Exceed the 100 kW/l Milestone for High Power Density Automotive Diesel Engines

2017-09-04
2017-24-0072
The paper describes the challenges and results achieved in developing a new high-speed Diesel combustion system capable of exceeding the imaginative threshold of 100 kW/l. High-performance, state-of-art prototype components from automotive diesel technology were provided in order to set-up a single-cylinder research engine demonstrator. Key design parameters were identified in terms boost, engine speed, fuel injection pressure and injector nozzle flow rates. In this regard, an advanced piezo injection system capable of 3000 bar of maximum injection pressure was selected, coupled to a robust base engine featuring ω-shaped combustion bowl and low swirl intake ports. The matching among the above-described elements has been thoroughly examined and experimentally parameterized.
Technical Paper

Application of a Dual Fuel Diesel-CNG Configuration in a Euro 5 Automotive Diesel Engine

2017-03-28
2017-01-0769
An increasing interest in the use of natural gas in CI engines is currently taking place, due to several reasons: it is cheaper than conventional Diesel fuel, permits a significant reduction of carbon dioxide and is intrinsically clean, being much less prone to soot formation. In this respect, the Dual Fuel concept has already proven to be a viable solution, industrially implemented for several applications in the heavy duty engines category. An experimental research activity was devoted to the analysis of the potentiality offered by the application of a Dual Fuel Diesel-CNG configuration on a light duty 2L Euro 5 automotive diesel engine, equipped with an advanced control system of the combustion. The experimental campaign foresaw to test the engine in dynamic and steady state conditions, comparing engine performance and emissions in conventional Diesel and Dual Fuel combustion modes.
Journal Article

Impact of RME and GTL Fuel on Combustion and Emissions of a “Torque-Controlled” Diesel Automotive Engines

2010-05-05
2010-01-1477
The present paper describes some results of a research project aimed at studying the impact of alternative fuels blends on the emissions and fuel consumption of an Euro 5 automotive diesel engine. Two alternative fuels were chosen for the experiments: RME and GTL. The tests were done in the three most important operating conditions for the engine emission calibration. Moreover, the NOx-PM trade-off by means of EGR sweep was performed in the same operating conditions, in order to evaluate the engine EGR tolerability when burning low sooting fuels as the RME. The investigations put in evidence that the impact of the alternative fuels on modern diesel engines remains significant. This also depends on the interaction between the alternative fuel characteristics and the engine-management strategies, as described in detail in the paper.
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