首页> 外文期刊>Journal of environmental sciences >Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer
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Morphological and semi-quantitative characteristics of diesel soot agglomerates emitted from commercial vehicles and a dynamometer

机译:商用车和测功机排放的柴油机烟灰团块的形态和半定量特征

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Diesel soot aggregates emitted from a model dynamometer and 11 on-road vehicles were segregated by a micro-orifice uniform deposit impactor (MOUDI). The elemental contents and morphological parameters of the aggregates were then examined by scanning electron microscopy coupled with an energy dispersive spectrometer (SEM-EDS), and combined with a fractional Brownian motion (fBm) processor. Two mode-size distributions of aggregates collected from diesel vehicles were confirmed. Mean mass concentration of 339 mg/m{sup}3 (dC/dlog d{sub}p) existed in the dominant mode (180-320 nm). A relatively high proportion of these aggregates appeared in PM1, accentuating the relevance regarding adverse health effects. Furthermore, the fBm processor directly parameterized the SEM images of fractal like aggregates and successfully quantified surface texture to extract Hurst coefficients (H) of the aggregates. For aggregates from vehicles equipped with a universal cylinder number, the H value was independent of engine operational conditions. A small H value existed in emitted aggregates from vehicles with a large number of cylinders. This study found that aggregate fractal dimension related to H was in the range of 1.641-1.775, which is in agreement with values reported by previous TEM-based experiments. According to EDS analysis, carbon content ranged in a high level of 30%-50% by weight for diesel soot aggregates. The presence of Na and Mg elements in these sampled aggregates indicated the likelihood that some engine enhancers composed of biofuel or surfactants were commonly used in on-road vehicles in Taiwan. In particular, the morphological H combined with carbon content detection can be useful for characterizing chain-like or cluster diesel soot aggregates in the atmosphere.
机译:从模型测力计和11辆公路车辆排放的柴油机烟灰聚集体通过微孔均匀沉积撞击器(MOUDI)进行分离。然后,通过扫描电子显微镜与能量色散光谱仪(SEM-EDS)结合,并结合分数布朗运动(fBm)处理器,对聚集体的元素含量和形态参数进行了检查。确认了从柴油车辆收集的骨料的两种模式大小分布。在主导模式(180-320 nm)下,平均质量浓度为339 mg / m {sup} 3(dC / dlog d {sub} p)。这些聚集体中相对较高的比例出现在PM1中,突显了其与不良健康影响的相关性。此外,fBm处理器直接对分形样聚集体的SEM图像进行参数化,并成功地量化了表面纹理,以提取聚集体的赫斯特系数(H)。对于配备通用气缸号的车辆的骨料,H值与发动机工况无关。具有大量气缸的车辆排放的聚集体中存在较小的H值。这项研究发现与H相关的总分形维数在1.641-1.775的范围内,这与以前基于TEM的实验报道的值一致。根据EDS分析,对于柴油机烟灰聚集体,碳含量在按重量计30%-50%的高水平范围内。在这些聚集体中,Na和Mg元素的存在表明,某些由生物燃料或表面活性剂组成的发动机增强剂很可能在台湾的公路车辆中使用。特别地,形态学H与碳含量检测相结合可用于表征大气中的链状或簇状柴油机烟灰聚集体。

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