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 NO_x storage and reduction technology. A full-scale engine rig has been constructed and stationary NO_x reduction tests performed.

In the NO_x storage and reduction approach, NO_x 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 NO_x reduction tests have been performed at nine load points on an engine rig. They have shown that a stationary NO_x reduction of between 25-53% is achievable at most load points depending on the temperature.

The high oxygen content in the exhaust gas leads to the oxidation 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 examined.