University of California, Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), 1084 Columbia Avenue, Riverside, CA 92507, USA; Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California, Riverside, CA 92521, USA.
University of California, Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT), 1084 Columbia Avenue, Riverside, CA 92507, USA; Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California, Riverside, CA 92521, USA.
Sci Total Environ. 2022 May 20;822:153583. doi: 10.1016/j.scitotenv.2022.153583. Epub 2022 Jan 31.
This manuscript contains an assessment of tailpipe emissions and secondary aerosol formation from two in-use heavy-duty diesel vehicles (HDDVs) with different aftertreatment systems when operated with ultra-low sulfur diesel (ULSD) and hydrogenated vegetable oil (HVO) operated on a chassis dynamometer. Secondary aerosol formation was characterized from the HDDVs' diluted exhaust collected and photochemically aged in a 30 m mobile atmospheric chamber. Primary nitrogen oxide (NOx) and particulate matter (PM) emissions were reduced for both vehicles operating on HVO compared to ULSD. For the vehicles with no selective catalytic reduction (SCR) system, secondary aerosol production was ~2 times higher for ULSD compared to HVO. The composition of primary aerosol was exclusively organic for the vehicle with no SCR system regardless of fuel type. The composition of secondary aerosol with HVO was primarily organic for the vehicle equipped with diesel particulate filter (DPF)/SCR system; however, when the same vehicle was tested with ULSD, the composition was ~20% organic (80% ammonium nitrate). The results reported here revealed that the in-use vehicle with no-SCR had a non-functioning DPF leading to dramatic increases in secondary aerosol formation when compared to the DPF/SCR vehicle. The high-resolution mass spectra analysis showed that the POA of HVO combustion contained relatively lower portion of CH class compounds (or higher CHO class compounds) compared to ULSD under the similar conditions, which can be rationalized by the higher cetane number of HVO. Substantial growth of oxidized organic aerosol (such as m/z 44 peak) were observed after 5 h of photochemical oxidation, consistent with aged organic aerosols present in the atmosphere. The CH fragment at m/z 57 peak was used as a tracer to calculate evolution of secondary organic aerosol formation.
本文评估了两辆在用重型柴油车（HDDV）在底盘测功机上使用超低硫柴油（ULSD）和加氢植物油（HVO）运行时的尾管排放和二次气溶胶形成情况。使用 30m 移动大气室收集并光化学老化 HDDV 的稀释排气，对二次气溶胶形成进行了特征描述。与 ULSD 相比，两辆装有 HVO 的车辆的主要氮氧化物（NOx）和颗粒物（PM）排放量均有所降低。对于没有选择性催化还原（SCR）系统的车辆，与 HVO 相比，ULSD 的二次气溶胶生成量约高 2 倍。对于没有 SCR 系统的车辆，无论燃料类型如何，初级气溶胶的组成均为有机。对于装有柴油机颗粒过滤器（DPF）/SCR 系统的车辆，HVO 的二次气溶胶组成主要为有机；然而，当同一辆车使用 ULSD 进行测试时，其组成约为 20%有机（80%硝酸铵）。这里报告的结果表明，与装有 DPF/SCR 系统的车辆相比，没有 SCR 的在用车辆的 DPF 不起作用，导致二次气溶胶形成急剧增加。高分辨率质谱分析表明，在相似条件下，HVO 燃烧的 POA 所含 CH 类化合物的比例相对较低（或 CHO 类化合物的比例较高），这可以用 HVO 的较高十六烷值来解释。在 5 小时的光化学氧化后，观察到氧化有机气溶胶（如 m/z 44 峰）大量增长，这与大气中存在的老化有机气溶胶一致。使用 m/z 57 峰的 CH 片段作为示踪剂来计算二次有机气溶胶形成的演变。
