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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.

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.

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.