Ammonia Cross-Sensitivity Eliminatin Method of NOx Sensor for UREA-SCR (Selective Catalytic Reduction) System

This paper reports an ammonia cross-sensitivity elimination filter for SCR systems. Since NO
_X
sensors are cross sensitive to NH
₃
, a reading of NO
_X
sensor could not be accurate. As the reading is inaccurate, the closed-loop SCR systems is unpredictable. The proposed filter can be applied to any kinds of NO
_X
sensors and effectively remove the cross-sensitivity. Single gas and mixed exhaust gas tests are conducted. The results show the evident removal of NH
₃
in both single gas and mixed gases experiments. The experiments show the filtering method can considerably improve the accuracy of NO
_X
concentration measurement in Urea-SCR systems.