Abstract:

The on-board emission analysis system was used to carry out the actual road emission tests with different load ratios to quantitatively evaluate the variation of emission per unit mileage and emission per unit engine work with load ratio of heavy-duty vehicles, using 6 vehicles of stage VI of the National Standard and 2 vehicles of stage V of the National Standard. The results show that the load correction coefficient of particulate number (PN) emission per unit mileage of stage VI vehicles increases significantly with the increase of load ratio, and the slope of the fitted curve is 0.011 9, while the slope of stage 5 vehicle is 0.001 2, which is much lower than that of stage VI vehicle. With the increase of the load ratio, the PN and NO_x emissions per unit engine work increase, CO₂ emissions remain unchanged, and CO emissions decrease. When driving the same mileage, the larger the load ratio, the higher the PN emission level per unit vehicle mass, and the lower the emission levels of CO, CO₂ and NO_x. Under the condition of high load ratio, the National VI vehicles show high PN peaks in the initial urban stage and the final high-speed stage.

Key words: heavy-duty vehicle, emissions, particulate number (PN), load ratio, load correction factor