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Technical Paper

Development of a Physically/Chemically Based Approach for 2-Stage Ignition Delay Calculation in Medium Speed Dual-Fuel Engines

2019-09-09
2019-24-0068
Considering the upcoming global sulfur limitation for maritime fuels and the existing IMO Tier III legislation, natural gas as a fuel will become more important in the shipping sector. One way to use natural gas is the dual-fuel (DF) combustion process where a homogeneous lean natural gas mixture is ignited by a micro pilot injection of diesel fuel. This paper presents the first major step towards a new combustion model for the prediction of the DF combustion in the context of a 1D simulation. The combustion models known from literature are based on empirical models of a steady jet. Here in most cases the package model of Hiroyasu is used. Because the injection timing of the diesel fuel is very early and the injection ends before ignition, the spray behavior differs from that of a steady jet. Especially the well-known end-of-injection transients lead to stronger entrainment and therefore affect the ignition delay.
Technical Paper

Analysis of the Effect of the Sampling Conditions on the Sub-23nm Particles Emitted by a Small Displacement PFI and DI SI Engines Fuelled with Gasoline and Ethanol

2019-09-09
2019-24-0155
The growing concerns on the emission of particles smaller than 23 nm, which are harmful to human health, lead to the necessity of introducing a regulation for these particles not yet included in the current emission standards. Considering that measurements of concentration of sub-23nm particles are particularly sensitive to the sampling conditions, it is important to identify an effective assessment procedure. Aim of this paper is the characterization of the effect of the sampling conditions on sub-23nm particles, emitted by PFI and DI spark ignition engines fuelled with gasoline, ethanol and a mixture of ethanol and gasoline (E20). The experimental activity was carried out on a 250 cm3 displacement single cylinder engine, four stroke equipped with a prototype gasoline direct injection (GDI) head. The tests were conducted at 2000 rpm and 4000 rpm full load, representative of the homologation urban driving cycle.
Technical Paper

A Mild Hybrid SIDI Turbo Passenger Car Engine with Rankine Waste Heat Recovery

2019-09-09
2019-24-0194
In the strive for more fuel-efficient vehicles all possible measures are considered to increase the efficiency of the combustion engine. 48V mild hybrid technology is one such measure; SIDI (Spark Ignited Direct Injection) engines with Miller technology another, while recovering energy from the engine waste heat (WHR) is yet an option to increase fuel conversion efficiency. Here, for the first time, we will publish the results from an advanced engineering project at Volvo Cars including all these components. We have successfully built an ethanol based Rankine system around a 4-cylinder, 2.0 litre SIDI-engine, including 48V mild hybrid technology. The Rankine system uses the engine exhaust as heat source, while the expansion of the ethanol steam occurs in an axial piston expander coupled both electrically to the hybrid system and mechanically to the engine crankshaft.
Technical Paper

Combustion and Emission Characteristics of a Compression Ignition Engine Fueled with Diesel-LPG Blends

2019-09-09
2019-24-0038
Alternative fuels have recently attracted considerable attention due to their potential role in improving ambient air quality and mitigating global warming. Recent research has applied a variety of alternative fuels in an attempt to satisfy these requirements. Clearly, the alternative fuels industry needs to build confidence from fuels that perform well without adding considerable cost to the consumer. Although not a renewable fuel, liquefied petroleum gas (LPG) is a low-cost alternative fuel that might meet these needs; albeit temporarily. LPG is well known as an alternative fuel for spark ignition (SI) engines and, more recently, LPG systems have also been introduced to compression ignition (CI) engines. In this framework, to investigate the practical application and potential of this concept, diesel was blended with LPG, in different ratios (20-35% w/w). For this purpose, a single-cylinder test rig was properly adapted and, a standard common rail fuel injection system was employed.
Technical Paper

Optical Evaluation of Directly Injected Methane Using a Newly Developed Highly Repetitive Laser Diagnostics System

2019-09-09
2019-24-0134
New certification procedures like WLTP and RDE, as well as more stringent emission regulations in general, demand for further improvements in engine research and development. In order to meet the challenges of reducing pollutants while maintaining high performance and high efficiency many different approaches are discussed. Beside various concepts for new combustion strategies and alternative fuels, gaining detailed knowledge about the ongoing processes inside engines and combustion chambers during the different operation modes is of major importance. With their influence on combustion and emission formation, fuel injection and mixture formation are playing an important role for further improvements in modern propulsion systems. With the help of optical measurement systems based on laser induced (exciplex) fluorescence (LIF/ LIEF), an advanced understanding of these mechanisms can be obtained.
Technical Paper

A Novel 1D Co-Simulation Framework for the Prediction of Tailpipe Emissions Under Different IC Engine Operating Conditions

2019-09-09
2019-24-0147
The prediction of the pollutants emitted by internal combustion engines during driving cycles has been a challenge since the introduction of the emission regulation legislation. During the last decade, along with the more tightening limits and increased public concern about the matter of air quality, the possibility of simulating various driving tests with cost effective computing facilities has become a key feature for modern simulation codes. Many 1D simulation tools are available on the market, offering real time models capable of achieving the simulation of any driving cycle in limited time frames. These approaches are based on the extreme simplification of the engine geometry and on the adoption of engine maps, which, for any engine operating condition, give the engine output in terms of power, or torque, and of exhaust gas composition.
Technical Paper

A Study of Lean Burn Pre-chamber Concept in a Heavy Duty Engine

2019-09-09
2019-24-0107
Due to stringent emission standards, the demand for higher efficiency engines has been unprecedentedly high in recent years. Among several existing combustion modes, pre-chamber initiated combustion emerges to be a potential candidate for high-efficiency engines. Research on the pre-chamber concept exhibit higher indicated efficiency through lean limit extension while maintaining the combustion stability. In this study, different pre-chamber geometries were tested in a single-cylinder heavy-duty engine at different loads. The geometries were prepared with three different pre-chamber volumes and with three varying nozzle area to pre-chamber volume ratios. The pre-chambers were fueled with methane while two sets of experiments were conducted, the first with ethanol as main chamber fuel and the second with methane.
Technical Paper

Knock and Pre-Ignition Limits on Utilization of Ethanol in Octane–on–Demand Concept

2019-09-09
2019-24-0108
Octane-on-Demand (OoD) is a viable technology for reducing global greenhouse emissions from automobiles. The concept utilizes a low-octane fuel for most operating conditions. Previous research has focused on the minimum ethanol content required for achieving a specific load at a given speed as the low-octane fuel becomes knock limited as the load increases. However, it is also widely known that ethanol has a high tendency to pre-ignite, attributed by few to its high laminar flame speed and surface ignition tendency. Moreover, ethanol has a lower calorific value, requiring a larger fuel mass to be injected to achieve similar power. A larger fuel mass increases the oil dilution by the liquid fuel, creating precursors for pre-ignition. Hence the limits on ethanol addition owing to pre-ignition also needs consideration before the technology can be implemented.
Technical Paper

Experimental and Numerical Analysis of a Dual Fuel Operation of Turbocharged Engine at Mid-High Load

2019-09-09
2019-24-0122
Due to the potential benefits in lowering of the CO2 emissions and lowering of the cost of fuel, internal combustion engines fueled by natural gas are an attractive alternative to conventional diesel or gasoline engines. In compression ignition engines natural gas is used in a dual fuel combustion mode where the premixed mixture of natural gas and air is ignited by a small amount of directly injected diesel fuel. At constant intake pressure the load is varied by the total fuel mass, i.e. by the excess air ratio, with specific limit on the highest possible excess air ratio. If duel fuel combustion mode is used on a turbocharged engine with the variable geometry turbocharger, the mid-high load operating points can be obtained with number of different combinations of intake pressures and excess air ratios.
Technical Paper

Experimental Investigation of Combustion Characteristics in a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural-Gas Spark-Ignition Operation

2019-09-09
2019-24-0124
The conversion of existing diesel engines to natural gas operation can reduce U.S. dependence on petroleum imports and curtail engine-out emissions. Diesel compression ignition engines can be modified to NG spark ignition, by replacing the diesel injector with a NG spark plug and by fumigating NG in the intake manifold, to increase utilization of natural gas heavy-duty transportation sector. As the original diesel piston is maintained during conversion to decrease engine modification cost, the major of this study was to investigate the lean-burn characteristic of natural gas burning in this bowl-in-piston combustion chamber, which can accelerate the introduction of heavy-duty natural gas vehicles. Data analysis from engine experiments that changed spark timing indicated a two-stage combustion process in such retrofitted engines, which is different from traditional spark ignition engines.
Technical Paper

Numerical Investigation of Methanol Ignition Sequence in an Optical PPC Engine with Multiple Injection Strategies

2019-09-09
2019-24-0007
Methanol fuel is a genuine candidate on the alternative fuel market for internal combustion engines within heavy-duty transportation sector. The thermo-physical properties of methanol allow to achieve high thermodynamic efficiency and low emission levels with a good margin below the EURO VI standard using compression ignition (CI) engines with advanced injection strategies. However, due to a low stoichiometric air/fuel ratio and a high latent heat of vaporization there are two challenges that can be mentioned; (a) the tendency to a high pressure rise rate due to the rapid chemical kinetic driven ignition process and, (b) the required high inlet temperature to initiate compression ignition event. These challenges can be tackled for instance by employing multiple-injection strategies, which reduces both the maximal pressure rise rate and the demand on the high inlet temperature.
Technical Paper

Study of Fuel Octane Sensitivity Effects on Gasoline Partially Premixed Combustion Using Optical Diagnostics

2019-09-09
2019-24-0025
Partially premixed combustion (PPC) is a low-temperature combustion (LTC) concept that could deliver higher engine efficiency, as well as lower NOx and soot emissions. Gasoline-like fuels are beneficial for air/fuel mixing process under PPC mode because they have superior auto-ignition resistance to prolong ignition delay time. In current experiments, the high octane number gasoline fuel E10 (US market used gasoline, RON=91) and low octane number GCI blend fuel (RON=77) were tested respectively in a full-transparent AVL single cylinder optical compression ignition (CI) engine. Aiming at investigating the fuel sensitivity on engine performances under different combustion modes as well as soot particle emissions, the engine operating parameters and emission data were analyzed from CI to HCCI (homogeneous charge compression ignition) via PPC (partially premixed combustion) by changing fuel injection timing.
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 in heavy-duty engines powered with CNG dictated by stringent regulations in terms of emissions, has made it essential to study a specific Three-Way Catalyst (TWC). Oxygen storage phenomena characterize catalytic converter efficiency under real world driving operating conditions and, consequently, during strong dynamics in Air-to-Fuel (A/F) ratio. 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 lambda variation pattern of the engine exhaust stream, 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 at the tailpipe.
Technical Paper

Literature Review on Dual-Fuel Combustion Modelling

2019-09-09
2019-24-0120
In the search for low greenhouse gas propulsion, the dual fuel engine provides a solution to use low carbon fuel at diesel-like high efficiency. Also a lower emission of NOx and particles can be achieved by replacing a substantial part of the diesel fuel by for example natural gas. Limitations can be found in excessively high heat release rate (combustion-knock), and high methane emissions. These limitations are strongly influenced by operating parameters and properties of the used (bio)-gas. To find the dominant relations between fuel properties, operating parameters and the heat release rate and methane emissions, a combustion model is beneficial. Such a model can be used for optimizing the process, or can even be used in real time control. As precursor for such a model, the current state of art of dual fuel combustion modelling is investigated in this work. The focus is on high speed dual fuel engines for heavy duty and marine applications, with a varying gas/diesel ratio.
Technical Paper

Experimental Investigation of Combustion Timing of HVO, RME and Diesel Fuel in a Euro6 Car Engine During Transient Driving Cycles

2019-09-09
2019-24-0138
The current targets to decrease greenhouse gases production, to reduce fossil fuel dependency and to gain energy security and sustainability are driving demand on combustion engine fuels from renewable sources. Over last more than two decades, the effort resulted in utilization of first generation biofuels. Unfortunately, these fuels brought new dilemmas and challenges in general, such as food production competition and land use and, in case of fatty acid methyl esters for compression ignition engines, also technical challenges such as storage stability and deposit formation. The technical aspects are more pronounced as advanced technologies employed to mitigate pollutants related adverse effects are applied, mandating stringent fuel properties, while demand for fuels from renewable sources is rising. Utilization of particle filters and sensitive fuel systems are driving effort to develop compatible renewable biofuels which can be utilized at higher than current shares.
Technical Paper

Effect of Methane Number in a Diesel Engine Converted to Natural Gas Spark Ignition

2019-09-09
2019-24-0008
Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of year, and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to spark ignition operations simulated engine operation under lean-combustion, low-speed, and medium load conditions. To eliminate the effect of different gas energy density, three NG blends of similar lower heating value but different H/C ratio have been investigated at fixed spark timing.
Technical Paper

Multi-Level Modeling of Real Syngas Combustion in a Spark Ignition Engine and Experimental Validation

2019-09-09
2019-24-0012
Syngas produced from biomass gasification is being increasingly considered as a promising alternative to traditional fuels in Spark-Ignition (SI) Internal Combustion Engines (ICEs). This gaseous fuel, composed by a mixture of CO, CH4, H2, CO2, N2 (and other minor hydrocarbon compounds), is however characterized by an extreme variability of its composition and a low energy density. In order to assure good energy performance and stability of operation as the syngas composition slightly changes, numerical modeling can give an important contribution as a tool to investigate the main parameters affecting the combustion process development and the formation of main pollutants. The present work introduces a multi-level set of numerical approaches to a SI ICE fueled with syngas deriving from biomass gasification.
Technical Paper

On the HCCI Octane Boosting Effects of γ-Valerolactone

2019-09-09
2019-24-0026
Transportation sector is almost entirely powered by internal combustion engines (ICEs) burning petroleum-based liquid fuels. This makes the transportation sector the main culprit of global warming due to the large quantity of CO2 emission from burning these petroleum-based fuels. Over the last few decades, there are growing concerns over global warming and diminishing petroleum reserves. Such concerns have led to concentrated efforts directed at a paradigm shift from conventional fuels to renewable alternatives which can promote cleaner combustion. Therefore, future research directions should orient towards exploring new fuels suitable for future ICEs to achieve better engine efficiency and significantly less harmful emissions. One way to achieve these objectives is to focus on improving the combustion technology by developing new fuel-engine systems. Consequently, scientists and engineers are showing growing interest towards non-petroleum-based fuels coming from renewable resources.
Technical Paper

Heavy-Duty Compression-Ignition Engines Retrofitted to Spark-Ignition Operation Fueled with Natural Gas

2019-09-09
2019-24-0030
Natural gas is a promising alternative gaseous fuel due to its availability, economic, and environmental benefits. A solution to increase its use in the heavy-duty transportation sector is to convert existing heavy-duty compression ignition engines to spark-ignition operation by replacing the fuel injector with a spark plug and injecting the natural gas inside the intake manifold. The use of numerical simulations to design and optimize the natural gas combustion in such retrofitted engines can benefit both engine efficiency and emission. However, experimental data of natural gas combustion inside a bowl-in-piston chamber is limited. Consequently, the goal of this study was to provide high-quality experimental data from such a converted engine fueled with methane and operated at steady-state conditions, exploring variations in spark timing, engine speed and equivalence ratio.
Standard

Engine Oil Performance and Engine Service Classification (Other than "Energy Conserving")

2019-07-16
WIP
J183
This SAE Standard outlines the engine oil performance categories and classifications developed through the efforts of the Alliance of Automobile Manufacturers (Alliance), American Petroleum Institute (API), the American Society for Testing and Materials (ASTM), the Engine Manufacturers Association (EMA), International Lubricant Specification Advisory Committee (ILSAC), and SAE. The verbal descriptions by API and ASTM, along with prescribed test methods and limits are shown for active categories in Table 1 and obsolete categories in Table A1. Appendix A is a historical documentation of the obsolete categories. For purposes of this document, active categories are defined as those (a) for which the required test equipment and test support materials, including reference engine oils and reference fuels, are readily available, (b) for which ASTM or the test developer monitors precision for all tests, and (c) which are currently available for licensing by API EOLCS.
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