METHOD AND SYSTEM FOR ESTIMATING REAGENT QUALITY

摘要

In a method for estimating the quality of an urea based reagent in terms of urea concentration, the reagent is injected upstream of a SCR catalyst in an exhaust aftertreatment system. A demanded NOx conversion rate is set substantially lower than a currently estimated maximum NOx conversion rate of the SCR catalyst. An actual NOx conversion rate is monitored for a certain time period. The urea concentration of the reagent is estimated based on comparing the monitored actual NOx conversion and the demanded NOx conversion during the time period. A corresponding system is also disclosed.

主权项

1. Method for estimating the quality of an urea based reagent in terms of urea concentration, the reagent being injected upstream of a SCR catalyst in an exhaust aftertreatment system,comprising:
setting a demanded NOx conversion rate substantially lower than a currently estimated maximum NOx conversion rate of the SCR catalyst, wherein a degraded and aged SCR catalyst exhibits essentially the same NOx conversion rate as a new SCR catalyst at the demanded NOx conversion rate; monitoring an actual NOx conversion rate for a certain time period; and estimating the urea concentration of the reagent based on comparing the monitored actual NOx conversion and the demanded NOx conversion during the time period.