Browse Publications Technical Papers 2001-01-0517

Combined Silencers and Urea-SCR Systems for Heavy-Duty Diesel Vehicles for OEM and Retrofit Markets 2001-01-0517

Selective Catalytic Reduction (SCR) with NH3 or urea is one of the most effective methods for removal of NOx in exhaust from HD diesel engines with potential for achieving more than 90% NOx-reduction measured in the European transient or a US HD FTP test cycle. The present paper describes the following two systems;
  • One OEM UREA-SCR SILENCER, comprising a silencer with built-in catalyst. The system was tested on a Scania DC1205 320 kW diesel engine, which was calibrated for the Euro II emission standard. The test results showed that it is possible to reduce more than 85% of the NOx emission with an insignificant NH3 slip in the ETC transient test cycle. The pressure-drop of the system was measured at 80% of that of the engine's original silencer and the silencing performance was improved for low frequencies below 125 Hz.
  • One RETROFIT UREA-SCR SYSTEM for HD engines, comprising a silencer with built-in catalyst, an electronic urea injection control system, urea injection and a urea tank. The importance of injection strategy and the relation between urea/NOx ratio, ammonia slip and obtained NOx-removal was elucidated by transient tests with a 10 liter 190 kW Volvo HD excavator engine on test rig. NOx-removals of 77 to 88% were demonstrated in ETC and the European ISO 8178C1 off road test cycles with essentially no ammonia slip. 99.7% NOx reduction was obtained with a high NH3-slip of about 100 ppm, illustrating the potential of the urea SCR technology. The silencer contained 29 liter catalyst.


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