State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
Environ Pollut. 2020 Dec;267:115623. doi: 10.1016/j.envpol.2020.115623. Epub 2020 Sep 9.
Liquefied petroleum gas (LPG) as an alternative fuel is increasingly used in mainland China, few reports are however available about emissions from LPG-fueled vehicles. In this study, 26 LPG-fueled taxis in Guangzhou, south China were tested using a chassis dynamometer to obtain their emission factors of nitrogen oxides (NO) and volatile organic compounds (VOCs) under idle and cruising (10-60 km h) modes. The emission factors of NO on average increased with speed from 4.13 g kg-fuel at idling to 71.1 g kg-fuel at 60 km h at a slope of 10.6 g kg-fuel per 10 km h increase in speed. Alkanes were the most abundant (71.9%) among the VOCs in the exhaust, followed by alkenes (25.2%), ethyne (2.7%), and aromatic species (0.2%). Emission factors of VOCs at idling averaged 8.24 g kg-fuel, higher than that of 6.23-7.36 g kg-fuel when cruising at 10-60 km h, but their ozone formation potentials (OFPs) were lower at idling (15.8 g kg-fuel) than under cruising (19.1-23.8 g kg-fuel) largely due to higher emission of more reactive alkenes under cruising mode. Emissions of both NOx and VOCs increased significantly with mileages. Measured emission factors of NO and reactive VOCs in this study suggested that replacing the gasoline-powered taxis with the LPG-fueled taxis with LPG-gasoline bi-fuel engines and no efficient after-treatment devices would not benefit in reducing the emissions of ozone precursors, and strengthening the emission control for LPG vehicles with dedicated LPG engines and after-treatment converters, as did in Hong Kong, could further benefit in reducing the emission of photochemically active species when using LPG as alternative fuels.
液化石油气（LPG）作为一种替代燃料在中国内地的使用越来越广泛，但有关 LPG 燃料车辆排放的报道却很少。本研究采用底盘测功机对广州 26 辆 LPG 出租车进行了测试，以获得其在怠速和巡航（10-60km/h）模式下氮氧化物（NO）和挥发性有机化合物（VOCs）的排放因子。NO 的排放因子随速度的增加而增加，从怠速时的 4.13g kg-燃料增加到 60km/h 时的 71.1g kg-燃料，斜率为每 10km/h 增加 10.6g kg-燃料。在废气中，烷烃是最丰富的（71.9%），其次是烯烃（25.2%）、乙炔（2.7%）和芳烃（0.2%）。怠速时 VOCs 的排放因子平均为 8.24g kg-燃料，高于巡航时 10-60km/h 的 6.23-7.36g kg-燃料，但由于巡航时更具反应性的烯烃排放较高，其臭氧形成潜能（OFP）在怠速时（15.8g kg-燃料）低于巡航时（19.1-23.8g kg-燃料）。NOx 和 VOCs 的排放量均随里程数的增加而显著增加。本研究中测量的 NO 和反应性 VOCs 排放因子表明，用 LPG-汽油双燃料发动机和无高效后处理装置的 LPG 燃料出租车替代汽油动力出租车，不会有利于减少臭氧前体物的排放，而像在香港那样，加强对专用 LPG 发动机和后处理转化器的 LPG 车辆的排放控制，在使用 LPG 作为替代燃料时，将进一步有利于减少光化学反应活性物质的排放。
