Patent ID: 8181450
Filing Date: 2012-05-22
Classification: B01D,F01N,F02B,Y02A,Y02T

Abstract:
1. An apparatus for reducing NO x emissions in an engine exhaust gas stream, comprising: a NO an ammonia storage module configured to determine an ammonia storage modifier by comparing a current ammonia storage level and a target ammonia storage level, wherein the ammonia storage module comprises an ammonia adsorption look-up table and an ammonia desorption look-up table each including predetermined time constants corresponding to various reductant addition rates and SCR catalyst bed temperatures, wherein the ammonia storage module is configured to determine the current ammonia storage level by utilizing a time constant selected from one of the tables, and wherein the time constant is selected from the ammonia adsorption look-up table when the SCR catalyst is in an ammonia adsorption mode and from the ammonia desorption table when the SCR catalyst is in an ammonia desorption mode; an ammonia target module configured to determine an ammonia addition requirement, the ammonia addition requirement comprising an amount of ammonia added to the exhaust gas stream to achieve the NO a reductant target module configured to determine a reductant injection requirement, the reductant injection requirement comprising an amount of reductant added to the exhaust gas stream to achieve the ammonia addition requirement; wherein at least one of the NO