Effects of physical and chemical properties of diesel fuel on NOx emissions of heavy-duty diesel engines

In a diesel engine, both physical and chemical properties of the fuel affect exhaust emissions. This study focused on the separation of some physical and chemical effects of the fuel on the NO_x emission. The tests were conducted with a bus engine using four diesel fuels with different density and aromatics levels. The measurements were performed using five injection timing settings to screen the effects of changes in actual injection timing. When conventional diesel fuel was replaced by reformulated diesel, NO_x was reduced 7-13 %. Changes in the injection timing due to differences in the physical properties accounted only for a minor part (10-25 % relative) of the total reduction of NOx, whereas the greater part of the reduction (75-90 % relative) was due to other reasons, mainly fuel chemical properties.