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Diesel fuels derived from Fischer-Tropsch processes have a number of beneficial properties, including zero sulfur, high cetane, and near-zero aromatics content. Previous researchers have shown emissions benefits for using these fuels in light and heavy-duty diesel engines. A series of experimental fuels using neat F-T material or blends of F-T material with conventional cracked stocks was tested in diesel engines and produced lower emissions when compared to current diesel fuel. These experimental fuels cover a variety of boiling point ranges, extending from light naphtha to materials that are significantly heavier than conventional diesel fuels. All of the fuels show lower NOx and particulate emissions. F-T material can be used to increase the use of marginal refinery streams as diesel blend stocks and so increase the volume of low emission diesel fuels produced in current refineries.

This paper summarizes a program to investigate the impact of a variety of oxygenates on diesel exhaust emissions, especially particulate matter (PM) and NOx emissions. Oxygenates have been studied at great length already and have been shown to be an effective method for reducing particulate emissions, although high cost remains a barrier to their widespread use. Our objectives were to assess whether some oxygenates could be more effective than others and why. Fourteen different oxygenates were studied. Testing was carried out primarily in a single cylinder heavy duty Caterpillar engine under high and low load conditions. Complementary testing was performed in three vehicles spanning a range of vehicle technologies. Most of the testing used a single base fuel which served as the reference fuel although some tests were also done using a newly produced ultra low sulfur automotive diesel oil (ULSADO). Larger particulate matter reductions were found at high load than at low load.

Diesel fuel injection pumps are lubricated primarily by the fuel itself. Traditionally, fuel viscosity was used as a rough indicator of a fuel's ability to provide wear protection, but since the advent of low sulphur diesel, even some fuels of higher viscosity have been found capable of producing wear. This paper provides further insights into the main contributors to diesel fuel lubricity, their source and the impact of refinery processing. The most effective way to monitor lubricity is also considered. We have found that diesel lubricity is largely provided by trace levels of naturally occurring polar compounds which form a protective layer on the metal surface. Typical sulphur compounds do not confer this wear protection themselves rather it is the nitrogen and oxygen containing hetero-compounds that are most important. A complex mixture of polar compounds is found in diesel and some are more active than others.

The formation of Nitric oxide (NO) in a Diesel engine has been studied as a function of crank angle through-out the whole combustion cycle, using the Laser Induced Fluorescence (LIF) technique. Measurements were performed in an optically accessible one-cylinder, two-stroke, direct injection Diesel engine. The engine was operated in steady state at different loads and compression ratios. A tunable ArF excimer laser beam was used to excite the NO molecules in the D2∑+(v′=0) ← X2Π(v″=1) band at 193 nm. Dispersed fluorescence spectra allowed to discriminate between NO and interfering oxygen fluorescence. From the spectra, a relative measure for the NO density present in the probed volume of the cylinder was obtained. This density was transformed into an in-cylinder NO content, taking into account the changes in laser intensity, pressure, temperature and volume during the stroke.

The objective of this work was to investigate the effect of fuel properties on atomization and spray structure of a diesel engine fuel injector, based on PDA (Phase Doppler Anemometry) measurements. Few studies have addressed the question of how fuels affect droplet size and spray structure. Thus three diesel fuels were selected: two which broadly represent the range of base fuel properties seen in current European fuels and a third which contained a high treat rate of a detergent-type additive, which, being polar, may have some surface effects which could impact spray formation. This range of diesel fuels was injected into a high pressure and temperature wind tunnel, using a single hole Bosch injector. Phase Doppler Anemometry (PDA) was used to measure the diameter, velocity and arrival time of spray droplets passing through numerous radial and longitudinal positions in the spray.

Particulate matter in the air has become the focus of increased attention due to the concern of potential health effects. Among other sources, automotive vehicles are seen as a major contributor of fine particles. At present there is limited information available relating either to the number or size distribution of automotive particle emissions and detailed evidence has still to be established. To develop an understanding in the area of automotive particulate emissions a programme was carried out concentrating on tailpipe emissions as measured at the regulated particulate sampling point in a dilution tunnel. A previous literature study by CONCAWE had identified analytical techniques considered to be suitable for this application and which are capable of measuring both mass and number size distributions. Several variations of these techniques are available in the research field and the programme aimed to assess and compare their operation and performance.

The use of oxygenate materials derived from agricultural produce as transportation fuels is receiving considerable attention in Europe. Since they are produced from renewable resources, bio-fuels appear to offer no net CO2 emissions and reduce the dependence on fossil fuels. The true situation is more complex and the purpose of this paper is to clarify the issue by providing a review of available data from a European perspective. In the case of bio-ethanol, the energy consumed in producing the fuel can equal the energy content of the ethanol itself so that there are no net CO2 and virtually no energy gains. The use of methyl ester (RSME) produced from oil-seed rape (canola or colza) oil gives a positive energy balance, but even here half the energy content of the fuel is required in its manufacture. Oxygenated fuels can give lower emissions of HC and CO, but some emissions, notably NOx, can be increased, and effects on diesel particulates are variable.

Low temperature waxing of diesel vehicles is of continuing concern to vehicle manufacturers, fleet operators and diesel vehicle drivers. However, significant progress has been and is being made in addressing their needs for better protection against waxing problems in winter. In the past two years a new generation of fuel additive technology has become available which offers further improvements in performance over that produced by conventional flow improvers. Wax Anti-settling Flow Improvers (WAFI) modify the wax crystals so that they remain dispersed rather than settling to the bottom of the fuel tank. This paper presents data from field and dynamometer tests demonstrating the lower minimum operability temperatures resulting from use of these additives.