Characterization of Exhaust Emissions from Two Heavy Duty Vehicles Fueled with Eight Different Diesel Fuels

The impact on exhaust emissions of diesel fuel composition was studied by a comprehensive program compiled after discussions with the oil industry, the motor vehicle manufacturers and the Swedish Environmental Protection Agency. In order to reduce the emissions from diesel fueled vehicles different possibilities have to be taken into consideration such as improvement of the engine, use of exhaust purification devices and use of diesel fuels of improved quality. The aim of this investigation was to study the connection between certain fuel parameters and exhaust emissions. Eight different diesel fuels were used in the investigation and the emission tests were carried out using a city bus and a truck, driven on a chassis dynamometer. Both regulated andunregulated emissions were measured. In addition to the emission measurements samples were taken and prepared for biological testing. The investigation showed that there is a clear correlation between certain fuel parameters and the emissions and biological activity of the exhaust. Multivariate analysis was undertaken on groups of data derived from the eight blends of fuels in order to study the correlation between the fuel and emission parameters. A least square regression analysis of the correlation between 23 fuel parameters and 43 exhaust emission parameters resulted in correlation coefficients, which were higher than 0.95 for the two vehicles tested. It was confirmed that the most important fuel parameters to be controlled are the density, boiling point range, the content of aromatics and cetane index. In addition to these parameters the content of polycyclic aromatic hydrocarbons should be controlled and limited. Sulfur is also an important parameter to be controlled especially when the fuel is going to be used for vehicles equipped with catalysts or catalytically activated particulate filters.