Search Results

Environmentally adapted diesel fuels defined by the Swedish Government contain extremely low levels of sulphur and have limited aromatics contents. Road trials and pump durability tests of these fuels revealed unacceptable wear in injection pumps due to low lubricity. Additive solutions were identified using bench tests and then proven in field trials. Market experience has substantiated the findings that fuels using the chosen additive give fully satisfactory performance. This paper illustrates how practical solutions to lubricity questions can be found, and is applicable wherever specifications demand fuels requiring a high degree of hydroprocessing.

As a result of increasing concerns over air quality, environmental legislation has led to more stringent emissions limits for diesel engines and vehicles. This has affected both engine manufactures and fuel suppliers. Whereas in the US, only the fuel requirements for heavy-duty diesel engines are of key interest, in Europe light-duty diesel applications are also important since diesel-powered passenger vehicles are accepted by customers and their market penetration has increased rapidly. This paper gives an update of Shell's ongoing research on correlations between diesel fuel quality and particulate emissions in both heavy- and light-duty applications. In heavy-duty testing (both steady-state and transient), sulphur is the dominant fuel property affecting particulate emissions. After sulphur correction, fuel effects are small and can best be described by a combination of cetane number and density.

Total aromatics have no influence on particulate emissions. This is an unexpected finding from a comprehensive programme to determine the influence of diesel fuel properties on heavy-duty particulate emissions. 30 fuels and five engines representing a variety of manufacture/technology were tested. To reveal causative influences, key fuel properties were intentionally uncorrelated and had a wide range of values. Engine sensitivities to fuel quality were found to differ considerably. Properties that most influenced emissions were sulphur content, density and cetane number. Some engines were totally insensitive to polyaromatics but in others, small influences are possible. The emissions benefits of specific fuel property changes are quantified.