DIFFERENTIATION OF ROAD DIESEL AND HEATING GAS-OIL BY CHANGES IN FUELPROPERTIES AND ADDITION OF OXYGENATED COMPONENTS

A major part of urban traffic in many European cities is due to diesel -powered vehicles, which occasionally, albeit illegally, run on heatin g gas oil rather than the more expensive road diesel; this practice is no doubt abetted by the fact that the properties of the two fuels are quite similar. The purpose of the work described in this paper was to look into the possibility of altering the properties of heating oil s o as to make it less desirable as a diesel fuel but without adverse en vironmental effects. Tests were run with two diesel-powered vehicles a nd a domestic boiler and included measurements of emissions of smoke, carbon monoxide, unburnt hydrocarbons, nitrogen oxides, and boiler the rmal efficiency. Smoke opacity of diesel exhaust was found to have an almost linear relationship with many of the basic interrelated propert ies (cetane number, viscosity, density) of fuels with similar distilla tion characteristics, whereas the presence of heavier components tende d to increase smoke. Addition of aromatic oxygenates (cresols) reduced the cetane number of diesel fuel but at the same time reduced smoke a nd NOx in diesel exhaust; the same materials appeared to enhance the t hermal efficiency of the boiler and lower its smoke emissions, while s lightly increasing the emitted NO.