Aerosol Physics Laboratory, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, FI-33014, Finland.
Aerosol Physics Laboratory, Faculty of Engineering and Natural Sciences, Tampere University, P.O. Box 692, FI-33014, Finland; Department of Automotive and Mechanical Engineering, Metropolia University of Applied Sciences, P.O. Box 4071, FI-01600, Vantaa, Finland.
Environ Pollut. 2020 Oct;265(Pt B):114948. doi: 10.1016/j.envpol.2020.114948. Epub 2020 Jun 10.
Exhaust emissions from diesel vehicles are significant sources of air pollution. In this study, particle number emissions and size distributions of a modern Euro 5b -compliant diesel passenger car exhaust were measured under the NEDC and US06 standard cycles as well as during different transient driving cycles. The measurements were conducted on a chassis dynamometer; in addition, the transient cycles were repeated on-road by a chase method. Since the diesel particulate filter (DPF) removed practically all particles from the engine exhaust, it was by-passed during most of the measurements in order to determine effects of lubricant on the engine-out exhaust aerosol. Driving conditions and lubricant properties strongly affected exhaust emissions, especially the number emissions and volatility properties of particles. During acceleration and steady speeds particle emissions consisted of non-volatile soot particles mainly larger than ∼50 nm independently of the lubricant used. Instead, during engine motoring particle number size distribution was bimodal with the modes peaking at 10-20 nm and 100 nm. Thermal treatment indicated that the larger mode consisted of non-volatile particles, whereas the nanoparticles had a non-volatile core with volatile material condensed on the surfaces; approximately, 59-64% of the emitted nanoparticles evaporated. Since during engine braking the engine was not fueled, the origin of these particles is lubricant oil. The particle number emission factors over the different cycles varied from 1.0 × 10 to 1.3 × 10 #/km, and engine motoring related particle emissions contributed 12-65% of the total particle emissions. The results from the laboratory and on-road transient tests agreed well. According to authors' knowledge, high particle formation during engine braking under real-world driving conditions has not been reported from diesel passenger cars.
柴油车的废气排放是空气污染的重要来源。在这项研究中，根据 NEDC 和 US06 标准循环以及不同的瞬态驾驶循环，测量了现代符合 Euro 5b 标准的柴油乘用车尾气的颗粒数排放和粒径分布。测量是在底盘测功机上进行的；此外，通过追综法在道路上重复进行了瞬态循环。由于柴油颗粒过滤器（DPF）几乎从发动机排气中去除了所有颗粒，因此在大多数测量中都绕过了 DPF，以确定润滑剂对发动机尾气气溶胶的影响。行驶条件和润滑剂特性对废气排放有很大影响，尤其是颗粒的数量排放和挥发性特性。在加速和稳定速度期间，颗粒排放主要由不可挥发的烟尘颗粒组成，其粒径主要大于∼50nm，而与使用的润滑剂无关。相反，在发动机运转期间，颗粒数粒径分布呈双峰型，模态峰值分别在 10-20nm 和 100nm。热处理表明，较大的模态由不可挥发的颗粒组成，而纳米颗粒具有不可挥发的核心，表面上凝聚有挥发性物质；大约 59-64%的排放纳米颗粒蒸发了。由于在发动机制动期间发动机不供油，因此这些颗粒的来源是润滑油。不同循环的颗粒数排放因子从 1.0×10 #到 1.3×10 #/km 不等，与发动机运转相关的颗粒排放占总颗粒排放的 12-65%。实验室和道路瞬态测试的结果非常吻合。据作者所知，在实际驾驶条件下，柴油乘用车在发动机制动期间形成大量颗粒的情况尚未有报道。
