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The market share of Gasoline Direct Injection (GDI) vehicles has been increasing, promoted by its positive contribution to the overall fleet fuel economy improvement. It has however been reported that this type of engine is emitting more ultrafine particles than the Euro 6c Particle Number (PN) limit of 6·1011 particles/km that will be introduced in Europe as of September 2017 in parallel with the Real Driving Emission (RDE) procedure. The emissions performance of a Euro 6b GDI passenger car was measured, first in the OEM build without a Gasoline Particulate Filter (GPF) and then as a demonstrator with a coated GPF in the underfloor position. Regulated emissions were measured on the European regulatory test cycles NEDC and WLTC and in real-world conditions with Portable Emissions Measurement Systems (PEMS) according to the published European RDE procedure (Commission Regulation (EU) 2016/427 and 2016/646).

Modern diesel vehicles utilize two technologies, one fuel based and one hardware based, that have been motivated by recent European legislation: diesel fuel blends containing Fatty Acid Methyl Esters (FAME) and Diesel Particulate Filters (DPF). Oxygenates, like FAME, are known to reduce PM formation in the combustion chamber and reduce the amount of soot that must be filtered from the engine exhaust by the DPF. This effect is also expected to lengthen the time between DPF regenerations and reduce the fuel consumption penalty that is associated with soot loading and regeneration. This study investigated the effect of FAME content, up to 50% v/v (B50), in diesel fuel on the DPF regeneration frequency by repeatedly running a Euro 5 multi-cylinder bench engine over the European regulatory cycle (NEDC) until a specified soot loading limit had been reached.

Substantial advances in European road vehicle emissions have been achieved over the past 3 decades driven by strengthening revisions in emissions legislation and enabled by advances in fuel, vehicle engine and emissions control technologies. As both vehicle technology and emissions legislation in Europe continue to evolve, Concawe has conducted a study to examine the opportunities that fuels can provide to further reduce emissions from light-duty diesel passenger cars. Three European diesel cars spanning Euro 5, Euro 6b and Euro 6d-TEMP emissions certification levels have been tested over the cold-start WLTC (Worldwide harmonized Light-duty Test Cycle) with 6 fuels: an EN590-compliant B5 (petroleum diesel containing 5% biodiesel by volume), a bio-derived paraffinic diesel, a 50:50 blend of the aforementioned fuels, a low density petroleum-derived B5, a B30 and the same B30 additized with a high dose of cetane number improver.

Blends of gasoline, diesel fuel and ethanol (“dieseline”) have shown promise in engine studies examining low temperature combustion using compression ignition. They offer the possibility of high efficiency combined with low emissions of oxides of nitrogen and soot. However, unlike gasoline or diesel fuel alone, such mixtures can be flammable in the headspace above the liquid in a vehicle fuel tank at common ambient temperatures. Quantifying their flammability characteristics is important if these fuels are to see commercial service. The parameter of most interest is the Upper Flammable Limit (UFL) temperature, below which the headspace vapour is flammable. In earlier work a mathematical model to predict the flammability of dieseline blends, including those containing ethanol, was developed and validated experimentally. It was then used to study the flammability of a wide variety of dieseline blends parametrically.

The performance aspect of gasoline combustion has traditionally been measured using Research Octane Number (RON) and Motor Octane Number (MON) which describe antiknock performance under different conditions. Recent literature suggests that MON is less important than RON in modern cars and a relaxation in the MON specification could improve vehicle performance, while also helping refiners in the production of gasoline. At the same time, for the same octane number change, increasing RON appears to provide more benefit to engine power and acceleration than reducing MON. It has also been suggested that there could be fuel efficiency benefits (on a tank to wheels basis) for specially adapted engines, for example, operating at higher compression ratio, on very high RON (100+). Other workers have advocated the use of an octane index (OI) which incorporates both RON and MON to give an indication of octane quality.

Certain diesel fuel specification properties are considered to be environmental parameters according to the European Fuels Quality Directive (FQD, 2009/EC/30) and previous regulations. These limits included in the EN 590 specification were derived from the European Programme on Emissions, Fuels and Engine Technologies (EPEFE) which was carried out in the 1990’s on diesel vehicles meeting Euro 2 emissions standards. These limits could potentially constrain FAME blending levels higher than 7% v/v. In addition, no significant work has been conducted since to investigate whether relaxing these limits would give rise to performance or emissions debits or fuel consumption benefits in more modern vehicles. The objective of this test programme was to evaluate the impact of specific diesel properties on emissions and fuel consumption in Euro 4, Euro 5 and Euro 6 light-duty diesel vehicle technologies.

Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this; however, a gasoline/diesel mixture in a fuel tank can result in a flammable headspace, particularly at very cold ambient temperatures. A mathematical model to predict the flammability of dieseline blends, including those containing ethanol, was previously validated. In this paper, that model is used to study the flammability of dieseline blends parametrically. Gasolines used in the simulations had Dry Vapour Pressure Equivalent (DVPE) values of 45, 60, 75, 90 and 110 kPa.

Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this, but a practical concern is the flammability of the headspace vapours in the vehicle fuel tank. Gasoline is much more volatile than diesel so, at most ambient temperatures, the headspace vapours in the tank are too rich to burn. A gasoline/diesel mixture in a fuel tank therefore can result in a flammable headspace, particularly at cold ambient temperatures. A mathematical model is presented that predicts the flammability of the headspace vapours in a tank containing mixtures of gasoline and diesel fuel. Fourteen hydrocarbons and ethanol represent the volatile components. Heavier components are treated as non-volatile diluents in the liquid phase.