Ammonia storage feedback control to improve urea usage and NOx efficiency with experimental demonstration

Diesel exhaust emissions legislation is driving acceptable NOx emissions to ever lower levels. To continually meet the challenges presented by this trend, new SCR controls technologies must be considered as well as new ways to sense and control them. Ammonia storage controls technology was developed to manage ammonia utilization within a Selective Catalytic Reduction (SCR) sub-system and thereby facilitate the effective and efficient reduction of nitrogen oxides (NOx) in Diesel engine exhaust streams while at the same time improving urea usage and minimizing ammonia slip from the tailpipe. This technology was tested on a medium duty diesel engine using standard test and measurement procedure for engine certification by EPA.