Assignment

Not only the engine manufacturers have to do their homework, the fuel producing industry can play its part to the progress of diesel engines in nitrogen oxide and particle emissions.

Function

In a Diesel engine the exhaust gas composition is largely dependent on the quality of the Diesel fuel. The problem of sulphur is well known, DeNO_X-catalytic converters can only then function optimally, when the amount of sulphur in the Diesel fuel has been distinctly reduced. Sulphur reduces the amount of storage space for nitrogen oxides and is responsible for more frequent regeneration phases. Not quite as well known, are the influences of sulphur on the particle development and the working temperature of oxidation catalytic converters.

There are however, other parial aspects of Diesel fuel which are also important. Thus, by increasing the cetane number by 10, the cold starting- and running behaviour of a suitably adjusted engine would be considerably improved. If one did not have to set the engines up for diesel fuel having varying densities, then the emission values could also be improved. The fuel should also contain as few high-boiling-point components as possible. Indeed, most of the results emanating from improved fuel measures, would only be effective with an electronic diesel regulation.

In the production of optimised Diesel fuel, the earlier, only slight difference between Diese fuel and heating-oil now becomes much greater. If this really contains up to 1000 mg of sulphur per kg, the 10 mg/kg required for Central Europe, would be considerably exceeded. If in addition, there is no prescribed lowest cetane-number, one need not be surprised about, e.g., the cold running behaviour with extensive ignition delays and the possible resulting damages that occur. Together with the higher density for particle development, the exhaust gas cleansing system could be quickly be overburdened. 01/11