
One element of the "LOW NOx Combustion" concept is the very late fuel injection timing. In fact, retarded injection is the most effective, well-known and most widely used method for reducing NOx formation. Until now the drawback of this method has been the increased specific fuel consumption. To re-establish low fuel oil consumption the compression ratio of the engine is increased as a countermeasure, resulting in low NOx emissions and no penalty in terms of fuel consumption. Very late fuel injection timing in combination with a high compression ratio demands a modified injection rate. Sophisticated fuel injection equipment is consequently a key element in the concept (Figs. 2 and 3).
Figure 2. Basic principle of Low NOx Combustion.
Figure 3. Typical modifications for Low NOx Combustion.