Real-time emission test and evaluation method of heavy-duty diesel vehicle SCR system based on dynamic time warping

Selective catalytic reduction (SCR) technology is the most important technique to solve the high NOx emission of diesel vehicles. In-use heavy-duty diesel vehicles must undergo emission spot checks at inspection stations to avoid exceeding the NOx emission limits due to abnormal operation of the SCR system. A method that can quickly carry out in-situ emission tests on heavy-duty diesel vehicles on the road to evaluate SCR operation status is of great significance. In this paper, a method based on dynamic time warping (DTW ) is proposed to quickly judge the SCR operation status when the vehicle is stationary. The variation of similarity between SCR inlet NOx and SCR outlet O2, the variation of similarity between SCR outlet O2 and SCR outlet NOx, and the effect of SCR working efficiency on SCR outlet O2 were analysed through experiments, and the proposed method was validated.