[Characterization of Tailpipe Emissions from in-use Excavators]

In this paper, the objective is to characterize real-world tailpipe emissions for excavators. Eight excavators in several construction sites in Chengdu were selected in this study. A portable emission measurement system (PEMS) was used for real-world emissions measurements (i. e., CO, HC, NO, and PM_2.5) for three predefined operation modes:idling, moving, and working. The results showed that the tailpipe emissions of excavators vary depending on the operation mode as well as the equipment. NO emissions were relatively stable when the engine was idling compared to when the excavator was moving or doing actual work. In addition, excavators that complied to different emissions standards also exhibited different emissions, with those that met higher emission standards producing fewer emissions. For example, when comparing excavators complying with Stage Ⅱ emission standards to those complying with Stage Ⅰ emission standards, the NO and PM_2.5 emissions appeared to decrease. On average, the NO emissions decreased by 8%, 35%, and 5%, and the PM_2.5 emissions decreased by 88%, 87%, and 80% for the idling, moving, and working modes, respectively. Furthermore, the studies showed significant differences existed between the emissions factors in the real-world measurements and those recommended by national guidance. This indicated that real-world emission measurements of non-road equipment will play a key role in emissions inventory development. This study demonstrated that PEMS can be used to characterize real-world emissions from non-road equipment.