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Technical Paper

Well-to-Wheel Energy Use and Greenhouse Gas Emissions for Various Vehicle Technologies

2001-03-05
2001-01-1343
The well-to-wheel greenhouse gas (GHG) emissions and energy use of selected alternative vehicles are compared to those of a conventional gasoline vehicle. The vehicle technologies investigated are internal combustion engine, hybrid and fuel cell technology. The fuels are assumed to be produced from either crude oil or natural gas. Wherever possible real data has been used. The study shows that hybrid vehicles emit a similar amount of greenhouse gas as fuel cell vehicles. The diesel hybrid uses the least primary energy. The least greenhouse gas emissions are produced by natural gas and hydrogen hybrid and fuel cell vehicles.
Journal Article

Understanding the Octane Appetite of Modern Vehicles

2016-04-05
2016-01-0834
Octane appetite of modern engines has changed as engine designs have evolved to meet performance, emissions, fuel economy and other demands. The octane appetite of seven modern vehicles was studied in accordance with the octane index equation OI=RON-KS, where K is an operating condition specific constant and S is the fuel sensitivity (RONMON). Engines with a displacement of 2.0L and below and different combinations of boosting, fuel injection, and compression ratios were tested using a decorrelated RONMON matrix of eight fuels. Power and acceleration performance were used to determine the K values for corresponding operating points. Previous studies have shown that vehicles manufactured up to 20 years ago mostly exhibited negative K values and the fuels with higher RON and higher sensitivity tended to perform better.
Technical Paper

The Volumetric Efficiency of Direct and Port Injection Gasoline Engines with Different Fuels

2002-03-04
2002-01-0839
A study has been undertaken with a single-cylinder engine, based on the Mitsubishi GDi combustion system, that has the option of either port injection or direct injection. Tests have been undertaken with pure fuel components (methane, iso-octane, toluene and methanol), and a representative gasoline that has also been tested with the addition of 10% methanol and 10% ethanol. The volumetric efficiency depends both on the fuel and its time and place of injection. For stoichiometric operation with unleaded gasoline, changing from port injection to direct injection led to a 9% increase in volumetric efficiency, which was improved by a further 3% when 10% methanol was blended with the gasoline. The improvements in volumetric efficiency will be used to quantify the extent of charge cooling by fuel evaporation, and these will be compared with predictions assuming the maximum possible level of fuel evaporation.
Technical Paper

The Response of a Closed Loop Controlled Diesel Engine on Fuel Variation

2008-10-06
2008-01-2471
An investigation was conducted to elucidate, how the latest turbocharged, direct injection Volkswagen diesel engine generation with cylinder pressure based closed loop control, to be launched in the US in 2008, reacts to fuel variability. A de-correlated fuels matrix was designed to bracket the range of US market fuel properties, which allowed a clear correlation of individual fuel properties with engine response. The test program consisting of steady state operating points showed that cylinder pressure based closed loop control successfully levels out the influence of fuel ignition quality, showing the effectiveness of this new technology for markets with a wide range of fuel qualities. However, it also showed that within the cetane range tested (39 to 55), despite the constant combustion mid-point, cetane number still has an influence on particulate and gaseous emissions. Volatility and energy density also influence the engine's behavior, but less strongly.
Technical Paper

The Molecular Basis of the Rheological Behaviour of Lubricants

1999-10-25
1999-01-3611
The design of effective traction fluids and lubricants is facilitated by an understanding of how molecular structure within a fluid affects the behaviour of that fluid in-situ. Non-equilibrium molecular dynamics simulation has been used to analyse how molecules of different structures behave in a fluid and to determine the influence of these separate behaviours on the different rheological properties of the fluids.
Technical Paper

The Effects of Driveability on Emissions in European Gasoline Vehicles

2000-06-19
2000-01-1884
Fuel volatility and vehicle characteristics have long been recognised as important parameters influencing the exhaust emissions and the driveability of gasoline vehicles. Limits on volatility are specified in a number of world-wide / national fuel specifications and, in addition, many Oil Companies monitor driveability performance to ensure customer satisfaction. However, the relationship between driveability and exhaust emissions is relatively little explored. A study was carried out to simultaneously measure driveability and exhaust emissions in a fleet of 10 European gasoline vehicles. The vehicles were all equipped with three-way catalysts and single or multi-point fuel injection. The test procedure and driving cycle used were based on the European Cold Weather Driveability test method.
Technical Paper

Safety Considerations in Retailing Hydrogen

2002-06-03
2002-01-1928
To be used in public, untrained people must be able to handle hydrogen with the same degree of confidence and with no more risk than conventional liquid and gaseous fuels. Physical properties relevant to the safety of hydrogen as a fuel are reviewed and compared to gasoline, LPG and methane. The key parameters are flammability, detonability, ignition energy, materials compatibility, buoyancy and toxicity. For many years, Shell has conducted an experimental programme on gas safety, which has recently been extended to include hydrogen. A selection of results from this programme is presented.
Technical Paper

Relevance of Research and Motor Octane Numbers to the Prediction of Engine Autoignition

2004-06-08
2004-01-1970
Links between the RON, MON and Octane Index (OI) of a gasoline are explored and factors influencing knock severity are discussed. The OI was calculated by considering how the autoignition delay time changes with temperature and pressure. Three fuels were examined: a 65/35% toluene/heptane test fuel, and two primary reference fuels (PRF), one with the RON value of the test fuel and the other with the MON value. PRF autoignition times were taken from Adomeit et al and test fuel autoignition times were generated from mathematical models of RON/MON tests plus two experimental sets of engine autoignition data. The toluene/heptane OI depended strongly on engine conditions and could easily exceed the RON. With a lean mixture at high pressure it was 100.2 whereas the RON was only 83.9. Knock severity is governed by the nature of localized “hot spots”. Severe knock is associated with developing detonations towards the end of the delay time.
Technical Paper

Particulate and Hydrocarbon Emissions from a Spray Guided Direct Injection Spark Ignition Engine with Oxygenate Fuel Blends

2007-04-16
2007-01-0472
The blending of oxygenated compounds with gasoline is projected to increase because oxygenate fuels can be produced renewably, and because their high octane rating allows them to be used in substitution of the aromatic fraction in gasoline. Blending oxygenates with gasoline changes the fuels' properties and can have a profound affect on the distillation curve, both of which are known to affect engine-out emissions. In this work, the effect of blending methanol and ethanol with gasoline on unburned hydrocarbon and particulate emissions is experimentally determined in a spray guided direct injection engine. Particulate number concentration and size distribution were measured using a Cambustion DMS500. These data are presented for different air fuel ratios, loads, ignition timings and injection timings. In addition, the ASTM D86 distillation curve was modeled using the binary activity coefficients method for the fuel blends used in the experiments.
Technical Paper

Overview of the European “Particulates” Project on the Characterization of Exhaust Particulate Emissions From Road Vehicles: Results for Light-Duty Vehicles

2004-06-08
2004-01-1985
This paper presents an overview of the results on light duty vehicles collected in the “PARTICULATES” project which aimed at the characterization of exhaust particle emissions from road vehicles. A novel measurement protocol, developed to promote the production of nucleation mode particles over transient cycles, has been successfully employed in several labs to evaluate a wide range of particulate properties with a range of light duty vehicles and fuels. The measured properties included particle number, with focus separately on nucleation mode and solid particles, particle active surface and total mass. The vehicle sample consisted of 22 cars, including conventional diesels, particle filter equipped diesels, port fuel injected and direct injection spark ignition cars. Four diesel and three gasoline fuels were used, mainly differentiated with respect to their sulfur content which was ranging from 300 to below 10 mg/kg.
Technical Paper

Optimizing Engine Concepts by Using a Simple Model for Knock Prediction

2003-10-27
2003-01-3123
The objective of this paper is to present a simulation model for controlling combustion phasing in order to avoid knock in turbocharged SI engines. An empirically based knock model was integrated in a one-dimensional simulation tool. The empirical knock model was optimized and validated against engine tests for a variety of speeds and λ. This model can be used to optimize control strategies as well as design of new engine concepts. The model is able to predict knock onset with an accuracy of a few crank angle degrees. The phasing of the combustion provides information about optimal engine operating conditions.
Technical Paper

Optical and Analytical Studies on DPF Soot Properties and Consequences for Regeneration Behavior

2017-09-04
2017-24-0126
The removal of particulate matter (PM) from diesel exhaust is necessary to protect the environment and human health. To meet the strict emission standards for diesel engines an additional exhaust aftertreatment system is essential. Diesel particulate filters (DPF) are established devices to remove emitted PM from diesel exhaust. But the deposition and the accumulation of soot in the DPF influence the filter back pressure and therefore the engine performance and the fuel consumption. Thus a periodical regeneration through PM oxidation is necessary. The oxidation behavior should result in an effective regeneration mode that minimizes the fuel penalty and limits the temperature rise while maintaining a high regeneration efficiency. Excessive and fast regenerations have to be avoided as well as uncontrolled oxidations, which may lead to damages of the filter and fuel penalty.
Technical Paper

Optical Studies on the Influence of di-n-butyl ether (DNBE) on Combustion and Partical Number Emissions

2015-09-06
2015-24-2482
Finite fossil energy sources and carbon dioxide as a main cause for climate changes are still under critical discussion. Therefore, scientists work on the replacement of fossil by alternative diesel fuels from biomass. Hence, in this study the in-cylinder combustion and particle number emissions of di-n-butyl ether (DNBE), as a representative of second generation biofuels, and of reference diesel fuel (B0) for comparison were analyzed by several measurement techniques at different injection and boost pressures. The heat release rate and thus the ignition delay as well as the center of combustion were analyzed by monitoring the global in-cylinder pressure signal using a pressure sensor. The combustion process was also visualized by simultaneous imaging of the hydroxyl radical and a spectral range of soot luminescence. This allows the analysis of the in-cylinder soot formation and oxidation process.
Journal Article

Optical Studies about the Influence of Diesel Engine Operating Parameters on the Physicochemical Properties of Emitted Soot Particles

2013-09-08
2013-24-0184
This paper describes the influence of diesel engine operating parameters not only on the properties of the emitted soot particles but also on the whole engine chain of events, which was visualized by optical measurement techniques. The vapor and liquid phase of the injected diesel spray was observed simultaneously by laser-induced exciplex florescence (LIEF) to analyze mixture formation up to the visible start of combustion. The soot formation and oxidation process was evaluated by detecting a spectral range of the soot luminescence and the OH radical. The electrical mobility particle diameter as well as the primary particle size of the emitted soot particles were analyzed by a Scanning Mobility Particle Sizer (SMPS) and by High-Resolution Transmission Electron Microscopy (HR-TEM).
Technical Paper

Octane Response of a Highly Boosted Direct Injection Spark Ignition Engine at Different Compression Ratios

2018-04-03
2018-01-0269
Stringent regulations on fuel economy have driven major innovative changes in the internal combustion engine design. (E.g. CAFE fuel economy standards of 54.5 mpg by 2025 in the U.S) Vehicle manufacturers have implemented engine infrastructure changes such as downsizing, direct injection, higher compression ratios and turbo-charging/super-charging to achieve higher engine efficiencies. Fuel properties therefore, have to align with these engine changes in order to fully exploit the possible benefits. Fuel octane number is a key metric that enables high fuel efficiency in an engine. Greater resistance to auto-ignition (knock) of the fuel/air mixture allows engines to be operated at a higher compression ratio for a given quantity of intake charge without severely retarding the spark timing resulting in a greater torque per mass of fuel burnt. This attribute makes a high octane fuel a favorable hydrocarbon choice for modern high efficiency engines that aim for higher fuel economy.
Journal Article

Octane Response in a Downsized, Highly Boosted Direct Injection Spark Ignition Engine

2014-04-01
2014-01-1397
Increasingly strict government emissions regulations in combination with consumer demand for high performance vehicles is driving gasoline engine development towards highly downsized, boosted direct injection technologies. In these engines, fuel consumption is improved by reducing pumping, friction and heat losses, yet performance is maintained by operating at higher brake mean effective pressure. However, the in-cylinder conditions of these engines continue to diverge from traditional naturally aspirated technologies, and especially from the Cooperative Fuels Research engine used to define the octane rating scales. Engine concepts are thus key platforms with which to screen the influence of fundamental fuel properties on future engine performance.
Technical Paper

Octane Requirement and Efficiency in a Fleet of Modern Vehicles

2017-03-28
2017-01-0810
In light of increasingly stringent CO2 emission targets, Original Equipment Manufacturers (OEM) have been driven to develop engines which deliver improved combustion efficiency and reduce energy losses. In spark ignition engines one strategy which can be used to reach this goal is the full utilization of fuel octane number. Octane number is the fuel´s knock resistance and is characterized as research octane number (RON) and motor octane number (MON). Engine knock is caused by the undesired self-ignition of the fuel air mixture ahead of the flame front initiated by the spark. It leads to pressure fluctuations that can severely damage the engine. Modern vehicles utilize different strategies to avoid knock. One extreme strategy assumes a weak fuel quality and, to protect the engine, retards the spark timing at the expense of combustion efficiency. The other extreme carefully detects knock in every engine cycle and retards the spark timing only when knock is detected.
Technical Paper

Mechanism Analysis on the Effect of Fuel Properties on Knocking Performance at Boosted Conditions

2019-01-15
2019-01-0035
In recent years, boosted and downsized engines have gained much attention as a promising technology to improve fuel economy; however, knocking is a common issue of such engines that requires attention. To understand the knocking phenomenon under downsized and boosted engine conditions deeply, fuels with different Research Octane Number (RON) and Motor Octane Number (MON) were prepared, and the knocking performances of these fuels were evaluated using a single cylinder engine, operated under a variety of conditions. Experimental results showed that the knocking performance at boosted conditions depend on both RON and MON. While higher RON showed better anti-knocking performance, lower MON showed better anti-knocking performance. Furthermore, the tendency for a reduced MON to be beneficial became stronger at lower engine speeds and higher boost pressures, in agreement with previously published modelling work.
Journal Article

LNG Fuel Differentiation: DME/LNG Blends for HPDI Engines

2020-09-15
2020-01-2078
With increased awareness and scrutiny of greenhouse gas (GHG) emissions, the heavy-duty truck industry is on the lookout for solutions that can maximize GHG savings, through either lowering fuel consumption and lowering methane slip. This paper focuses on whether it is possible to provide a differentiated Liquefied Natural Gas (LNG) that supports the further improvement of a High-Pressure Direct Injection (HPDI) Engine. Desired improvements from this LNG blend are the lowering or substitution of the pilot Diesel use of the current HPDI engine, the lowering of the raw exhaust gas methane concentration and any additional performance improvements. Sixty-five substances were identified that could potentially be blended into cryogenic methane thus creating a differentiated LNG fuel.
Journal Article

Injector Fouling and Its Impact on Engine Emissions and Spray Characteristics in Gasoline Direct Injection Engines

2017-03-28
2017-01-0808
In Gasoline Direct Injection engines, direct exposure of the injector to the flame can cause combustion products to accumulate on the nozzle, which can result in increased particulate emissions. This research observes the impact of injector fouling on particulate emissions and the associated injector spray pattern and shows how both can be reversed by utilising fuel detergency. For this purpose multi-hole injectors were deliberately fouled in a four-cylinder test engine with two different base fuels. During a four hour injector fouling cycle particulate numbers (PN) increased by up to two orders of magnitude. The drift could be reversed by switching to a fuel blend that contained a detergent additive. In addition, it was possible to completely avoid any PN increase, when the detergent containing fuel was used from the beginning of the test. Microscopy showed that increased injector fouling coincided with increased particulate emissions.
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