Engine Dynamometer and Vehicle Performance of a Urea SCR-System for Heavy-Duty Truck Engines

The application of SCR deNOx aftertreatment was studied on two about 12 liter class heavy-duty diesel engines within a consortium project. Basically, the system consists of a dosage system for aqueous urea injection and a vanadia based SCR catalyst, without an upstream or downstream oxidation catalyst.

The urea injection system for a DAF and a Renault V.I. (Véhicules Industriels) diesel engine was calibrated on the engine test bench taking into account dynamic effects of the catalyst. For both engine applications NOx reduction was 81% to 84% over the ESC and 72% over the ETC. CO emission increased up to 27%. PM emission is reduced by 4 to 23% and HC emission is reduced by more than 80%. These results are achieved with standard diesel fuel with about 350 ppm sulfur.

The test engines and SCR deNOx systems were built into a DAF FT95 truck and a Renault V.I. Magnum truck. Tests on the vehicle dynamometer with the DAF truck have shown that after 60,000 km in operation NOx conversion and ammonia slip are still the same.