Stationary NOx storage and reduction experiments on a heavy-duty diesel engine rig using a bypass system

This work concerns exhaust gas cleaning for heavy-duty diesel engines by means of NOx storage and redn. technol. A full-scale engine rig has been constructed, and stationary NOx redn. tests performed. In the NOx storage and redn. approach, NOx is stored on a BaO surface as Ba(NO3)2 under long lean conditions and desorbed and reduced under short rich conditions. The rich conditions are created by injection of diesel fuel into the exhaust stream. The stationary NOx redn. tests have been performed at nine load points on an engine rig. They have shown that a stationary NOx redn. of between 25-53% is achievable at most load points depending on the temp. The high oxygen content in the exhaust gas leads to the oxidn. of the injected hydrocarbons and thus to a high fuel penalty. To lower the fuel consumption, the mass flow through the catalyst has been reduced under the regeneration periods. This was done using a bypass system with a pneumatic valve control. The extent of the reduced catalyst flow has been examd.