Refine Your Search

Topic

Search Results

Technical Paper

Emissive Behavior of a Heavy-Duty SI Gas Engine During WHTC

2019-09-09
2019-24-0121
In the arduous aim to reduce petroleum fuel consumption and toxic emissions, gaseous fuels can represent an alternative solution for heavy duty applications with respect to conventional liquid fuels. At the same time, the imposition of more stringent emissions regulations in the transport sector, is a crucial aspect to be considered also for the development of future gas engines. Scope of the present paper was to characterize a heavy duty spark ignition engine, under development for Euro VI compliance, with a particular focus on exhaust particulate emissions. In this sense, the engine was installed on a dynamic test bench, accurately instrumented to analyze combustion evolution, performance and exhaust pollutant emissions, along the World Harmonized Transient Cycle (WHTC).
Technical Paper

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

2019-09-09
2019-24-0111
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.
Technical Paper

Development of a Dedicated CNG Three-Way Catalyst Model in 1-D Simulation Platforms

2019-09-09
2019-24-0074
A growing interest towards heavy-duty engines powered with NG, dictated by stringent regulations in terms of emissions, has made it essential to study a specific Three-Way Catalyst (TWC). Oxygen storage phenomena characterize the catalytic converter efficiency under real world driving operating conditions and, consequently, during strong dynamics in Air-to-Fuel ratio (AFR). A numerical “quasi-steady” model has been set-up to simulate the chemical process inside the reactor. A dedicated experimental campaign has been performed in order to evaluate the catalyst response to a defined λ variation, thus providing the data necessary for the numerical model validation. In fact, goal of the present research activity was to investigate the effect of very fast composition transitions of the engine exhaust typical of the mentioned driving conditions (including fuel cutoffs etc.) on the catalyst performance and on related emissions.
Technical Paper

Key Fuel Injection System Features for Efficiency Improvement in Future Diesel Passenger Cars

2019-04-02
2019-01-0547
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.
Technical Paper

Assessment of the New Features of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector by Means of Engine Performance Characterization and Spray Visualization

2018-09-10
2018-01-1697
The application of more efficient compression ignition combustion concepts requires advancement in terms of fuel injection technologies. The injector nozzle is the most critical component of the whole injection system for its impact on the combustion process. It is characterized by the number of holes, diameter, internal shape, and opening angle. The reduction of the nozzle hole diameter seems the simplest way to promote the atomization process but the number of holes must be increased to keep constant the injected fuel mass. This logic has been applied to the development of a new generation of injectors. First, the tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate. The vertical movement of the needle generates an annulus area for the fuel delivery on 360 degrees, so controlling the atomization as a function of the vertical plate position.
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

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

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

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.
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

Experimental and Numerical Analysis of a High-Pressure Outwardly Opening Hollow Cone Spray Injector for Automotive Engines

2017-03-28
2017-01-0840
In the aim of reducing CO2 emissions and fuel consumption, the improvement of the diesel engine performance is based on the optimization of the whole combustion system efficiency. The focus of new technological solutions is devoted to the optimization of thermodynamic efficiency especially in terms of reduction of losses of heat exchange. In this context, it is required a continuous development of the engine combustion system, first of all the injection system and in particular the nozzle design. To this reason in the present paper a new concept of an open nozzle spray was investigated as a possible solution for application on diesel engines. The study concerns some experimental and numerical activities on a prototype of an open nozzle. An external supplier provided the prototypal version of the injector, with a dedicated piezoelectric actuation system, and with an appropriate choice of geometrical design parameters.
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.
Technical Paper

Multidimensional Simulations of Combustion in Methane-Diesel Dual-Fuel Light-Duty Engines

2017-03-28
2017-01-0568
The adoption of gaseous fuels for Light Duty (LD) engines is considered a promising solution to efficiently reduce greenhouse gases emissions and diversify fuels supplies, while keeping pollutants production within the limits. In this respect, the Dual Fuel (DF) concept has already proven to be, generally speaking, a viable solution, industrially implemented for several applications in the Heavy-Duty (HD) engines category. Despite this, some issues still require a technological solution, preventing the commercialization of DF engines in wider automotive fields, including the release of high amounts of unburned species, possibility of engine knock, chance of thermal efficiency reduction. In this framework, numerical simulation can be a useful tool, not only to better understand specific characteristics of DF combustion, but also to explore specific geometrical modifications and engine calibrations capable to adapt current LD architectures to this concept.
Technical Paper

Hydrocracked Fossil Oil and Hydrotreated Vegetable Oil (HVO) Effects on Combustion and Emissions Performance of “Torque-Controlled” Diesel Engines

2015-09-06
2015-24-2497
The present paper describes the results of a research activity aimed at studying the potential offered by the use of Hydrocracked fossil oil (HCK) and Hydrotreated Vegetable Oil (HVO) blends as premium fuels for next generation diesel engines. Five fuels have been tested in a light duty four cylinder diesel engine, Euro 5 version, equipped with closed loop control of the combustion. The set of fuels comprises four experimental fuels specifically formulated by blending high cetane HVO and HCK streams and oneEN590-compliant commercial diesel fuel representative of the current market fuel quality. A well consolidated procedure has been carried out to estimate, for the tested fuels, the New European Driving Cycle (NEDC) vehicle performance by means of the specific emissions at steady-state engine operating points.
Journal Article

Experimental Evaluation of Compression Ratio Influence on the Performance of a Dual-Fuel Methane-Diesel Light-Duty Engine

2015-09-06
2015-24-2460
The paper reports an experimental study on the effect of compression ratio variation on the performance and pollutant emissions of a single-cylinder light-duty research diesel engine operating in DF mode. The architecture of the combustion system as well as the injection system represents the state-of-the-art of the automotive diesel technology. Two pistons with different bowl volume were selected for the experimental campaign, corresponding to two CR values: 16.5 and 14.5. The designs of the piston bowls were carefully performed with the 3D simulation in order to maintain the same air flow structure at the piston top dead center, thus keeping the same in-cylinder flow characteristics versus CR. The engine tests choice was performed to be representative of actual working conditions of an automotive light-duty diesel engine.
Technical Paper

Characterization of Combustion and Emissions in Light-Duty Diesel Engines Using High-Glycerol-Ethers/Diesel Blends

2015-09-06
2015-24-2445
In this paper, a detailed analysis of combustion and emissions is carried out on both metal and optical light duty diesel engines equipped with up-to-date combustion architecture. Both engines were fed with glycerol ethers mixture (GEM) in blend (10% and 20% v/v) within a commercial diesel fuel. The engines ran in significant operating points in the NEDC (New European Driving Cycle) emission homologation area. The results of the experimental campaign on the metal engine show comparable performances between the diesel/GEM blends and the diesel fuel and demonstrate benefits mainly in terms of soot production. The exhaust particles diameters of diesel/GEM blends shift toward smaller dimensions and the total number decreases. Moreover, at lower load conditions, the outputs show a worsening of the unburnt mainly ascribable to the fuel characteristics.
Technical Paper

Investigation of the Effect of Compression Ratio on the Combustion Behavior and Emission Performance of HVO Blended Diesel Fuels in a Single-Cylinder Light-Duty Diesel Engine

2015-04-14
2015-01-0898
Hydrotreated vegetable oil (HVO) is a renewable high quality paraffinic diesel that can be obtained by the hydrotreating of a wide range of biomass feedstocks, including vegetable oils, animal fats, waste oils, greases and algal oils. HVO can be used as a drop-in fuel with beneficial effects for the engine and the environment. The main objective of this study was to explore the potential of HVO as a candidate bio blendstock for new experimental formulations of diesel fuel to be used in advanced combustion systems at different compression ratios and at high EGR rates in order to conform to the Euro 6 NOx emission standard. The experiments were carried out in a single-cylinder research engine at three steady-state operating conditions and at three compression ratios (CR) by changing the piston.
Technical Paper

Estimation of TTW and WTW Factors for a Light Duty Dual Fuel NG-Diesel EU5 Passenger Car

2014-04-01
2014-01-1621
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 in the amount of emitted carbon dioxide and is intrinsically cleaner, being much less prone to soot formation. In this respect, the Dual Fuel (DF) concept has already proven to be a viable solution, industrially implemented for several applications in the high duty engines category. Despite this, some issues still require a technological solution, preventing the commercialization of DF engines in wider automotive fields: the release of high amounts of unburned fuel, the risk of engine knock, the possible thermal efficiency reduction are some factors regarding the fuel combustion aspect. DF configuration examined in the present paper corresponds to Port Fuel Injection of natural gas and direct injection of the Diesel Fuel.
Technical Paper

Emission Reduction Technologies for the Future Low Emission Rail Diesel Engines: EGR vs SCR

2013-09-08
2013-24-0087
The EU emission standards for new rail Diesel engines are becoming even more stringent. EGR and SCR technologies can both be used to reduce NOx emissions; however, the use of EGR is usually accompanied by an increase in PM emissions and may require a DPF. On the other hand, the use of SCR requires on-board storage of urea. Thus, it is necessary to study these trade-offs in order to understand how these technologies can best be used in rail applications to meet new emission standards. The present study assesses the application of these technologies in Diesel railcars on a quantitative basis using one and three dimensional numerical simulation tools. In particular, the study considers a 560 kW railcar engine with the use of either EGR or SCR based solutions for NOx reduction. The NOx and PM emissions performances are evaluated over the C1 homologation cycle.
Journal Article

Analysis of Nozzle Coking Impact on Emissions and Performance of a Euro5 Automotive Diesel Engine

2013-09-08
2013-24-0127
The present paper reassumes the results of an experimental study focused on the effects of the nozzle injector's coking varying the flow number (FN); the performance and emissions of an automotive Euro5 diesel engine have been analyzed using diesel fuel. As the improvement of the diesel engine performance requires a continuous development of the injection system and in particular of the nozzle design, in the last years the general trend among OEMs is lowering nozzle flow number and, as a consequence, nozzle holes size. The study carried out moves from the consideration that a reduction of the nozzle holes diameter could increase the impact of their coking process. For this purpose, an experimental campaign has been realized, testing the engine in steady state in three partial load operating points, representative of the European homologation driving cycle, and in full load conditions.
X