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This program examined the PAH emissions from two diesel engines representing state-of-the-art technology. One heavy-duty engine, a DDC Series 60, used in highway trucks, and one medium-duty engine, Navistar DTA-466, used in pick-up and delivery type vehicles. The medium-duty engine was tested for engine out emissions and with two different sized exhaust oxidation catalysts. Both of the catalysts were composed of a ceramic monolith coated with a palladium type catalyst. Both engines were tested according to the US EPA transient emissions test on a series of diesel fuels blended with varying aromatics and PAH contents to determine the impact of fuel quality on emissions. All diesel fuels had a low sulphur content (<0.05%) to minimize the formation of sulphate. The particulate matter was collected on teflon-coated filters, backed up with polyurethane foam filters to capture the vapour phase PAH.

A joint industry study was carried out to determine whether or not the use of up to 100 ppm Drag Reducing Additive (DRA) in diesel fuel would result in any short or medium term harmful effects. The study concluded that under normal circumstances, the DRA-treated diesel delivered to end-user equipment should be sheared to an acceptable level that will not cause problems, e.g. poor low temperature operability. Within the medium term, the use of DRA should not result in unusual deposits in the combustion chamber or the fuel injection systems. Based on these findings, the technical committee has approved the use of DRA in Transnorthern Pipeline, Ontario/Quebec, Canada.

Recent trends predicted by the Petroleum Industry are showing an increased demand for diesel fuel. This is because of the increase in diesel vehicles in North America due to the excellent fuel economy of the diesel engine. This trend will, however, tax the crude barrel for diesel fuel owing competing demands for jet fuel, kerosene, and heating oil. A way of overcoming the projected shortages of diesel fuel is through the use of specially designed flow improvers. These additives enable the blending of higher cloud point winter diesel fuels while maintaining satisfactory low temperature performance. A series of winter field tests have been conducted to demonstrate the effectiveness of these products. In over-the-road tests it was shown that flow improved diesel fuels will operate satisfactorily down to 6-13°C below their cloud points. The actual performance was found to be dependent upon the fuel/additive combination and the particular engine fuel system design.