[Analysis of Activity and Its Emissions Trend for Construction Equipment in China].

Emissions from non-road equipment are attracting more attention due to their increasing contribution to air pollution. Thus, an accurate estimate of emission inventory for non-road equipment is imperative for air quality management and improvement. Activity data from a large range of construction equipment were collected from multiple sources, including on-site/phone interviews and literature review, and used for further analysis to characterize its operations. Activity analysis of construction equipment included:①activity of construction equipment by type (functionality); ②activity differences by geographical area; and ③activity differences by age. A back-propagation neural network model was developed to estimate the construction equipment population in China from 2018 to 2025. Furthermore, real-world measurements of emissions were made on 47 selected examples of construction equipment using a portable emission measurement system. Population, activity, and emission factors were then combined to develop emission inventories for construction equipment in China from 2015 to 2025. The results showed that activity of construction equipment differs by type or functionality, ranging from 1439 to 4332 hours per year. Furthermore, there are differences in activity by as much as three times due to geographical area differences for the same construction equipment type. In general, activity of construction equipment decreases as it ages by a rate of approximately 140 to 150 hours per year. It is estimated that CO, HC, NO, and PM2.5 emissions of construction equipment in China in 2015 were approximately 2.099, 0.462, 3.452, and 0.574 million tons, respectively. Compared to 2015, due to the slow growth of the construction equipment population, CO, HC, and PM2.5 emissions will decrease by 2.4%-33.1% and 7.1%-64.7% by 2020 and 2025, respectively, depending on pollutant. It should be noted that NO emissions appear to increase slightly for the first several years in the future, but then decrease after 2020. As increasingly stringent regulations have been enforced for on-road vehicles, but less has been done regarding non-road equipment, although total emissions from non-road equipment continue to decrease, their contribution to air pollution will continue to increase; they should therefore be one of the focuses for future work.

[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 PM2.5) 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 PM2.5 emissions appeared to decrease. On average, the NO emissions decreased by 8%, 35%, and 5%, and the PM2.5 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.