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The Effect of Fuel Composition Including Aromatics Content on Emissions From a Range of Heavy-Duty Diesel Engines
Published May 05, 1993 by Coordinating European Council in Belgium
The influence of fuel properties and chemical composition on regulated diesel particulate emissions during operation of the European R49 13-mode cycle has been examined. Four multi-cylinder engines were tested to produce broadly applicable conclusions. Since fuel properties are usually strongly correlated, making extraction of the effects of individual properties difficult, this study used three fuel sets having a wide range of properties and in which the correlations between certain key properties were broken.
The contribution of fuel sulphur to particulate emissions as sulphate and associated water was confirmed to depend linearly on the fuel sulphur content, with engine dependent Fuel Sulphur Conversion Ratios of 1 to 2%.
The influence of fuel density on particulate emissions was found to be strongly dependent on (and predictable from) the particulate load range characteristics of individual engines. For purposes of comparing fuels, constant torque operation was confirmed to compensate for fuel density differences except in engines with complex timing management systems.
After fuel sulphur and density effects are accounted for, there remain residual fuel quality effects on particulate emissions that are consistent with a linear dependence on cetane number and are engine dependent in magnitude.
Particulate emissions from all the engines are fully explained by a model that includes fuel sulphur content, density and cetane number. Inclusion of fuel aromatics content in the model was found to be unnecessary although the possibility of an aromatics influence cannot be completely ruled out.
The effects of changes in specific fuel properties on particulate emissions are quantified and presented as fractions of the Euro-1 emissions limit.