Patent ID: 11927126
Assignee: PACCAR INC
Field: Chemical engineering (Chemistry)
Classification: CPC F  B  Y | IPC B  F

Claim 0:
1. A method of evaluating DEF quality in an emissions aftertreatment system (EAS) including an upstream selective catalytic reduction (SCR) unit and a downstream SCR unit, the method comprising:
during steady state operation of the EAS, varying an ammonia to NOx ratio of an internal combustion engine exhaust gas entering the upstream SCR unit;
determining a NOx conversion efficiency of the upstream SCR unit at a plurality of different ammonia to NOx ratios of the internal combustion engine exhaust gas;
comparing the determined NOx conversion efficiency of the upstream SCR unit to a target NOx conversion efficiency for the upstream SCR unit;
evaluating quality of diesel exhaust fluid (DEF) provided to the EAS by directly using a result of the comparing the determined NOx conversion efficiency of the upstream SCR unit to the target NOx conversion efficiency for the upstream SCR unit in the evaluating quality of the diesel exhaust fluid;
using a result of the evaluating quality of DEF provided to the EAS in adjusting the dosing of the DEF to the EAS; and
when the ammonia to NOx ratio of the internal combustion engine exhaust gas entering the upstream SCR unit is varied during the steady state operation of the EAS, reducing NOx content of the internal combustion engine exhaust gas in the downstream SCR unit.