Abstract:

The effect of different emission cycles （WLTC and CLTC） and catalyst states （fresh and aged） on NH₃ emission of a 1.5T SUV is studied. Experimental research shows that the original NH₃ emission of the engine is very low， but after the first ternary catalyst， the NH₃ emission significantly increases. After catalyst aging， the OSC decreases and the internal air fuel ratio fluctuates significantly. NH₃ emission from aged catalysts increases compared to that from fresh catalysts. The catalyst state， emission cycle， and engine air fuel ratio have a significant impact on NH₃ emission， which is of guiding significance for catalyst design and calibration optimization.

Key words: NH₃ emission, TWC, emission cycle, air fuel ratio