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Numerical study on evolution of ultrafine particles emitted from vehicle exhaust with multi-dynamical behaviors
Atmospheric Environment ( IF 4.2 ) Pub Date : 2021-01-01 , DOI: 10.1016/j.atmosenv.2020.117916
Guangping Xu , Jiasong Wang , Xinqi Qiao

Abstract In this study, a numerical investigation is performed to simulate the evolution process of ultrafine particles emitted from diesel vehicle exhausts. The Taylor expansion method of moments (TEMOM)-CFD coupled model is primarily applied to the non-spherical particles for simultaneously simulating four kinds of particle dynamical behaviors including coagulation, deposition, condensation and nucleation. Compared with previous simulation studies, the developed model shows closer results to the experimental data. The effects of initial particle number, initial particle size, environmental temperature, relative humidity, fuel sulfur content, and exhaust velocity on the evolution process are systematically analyzed. The results show that the increase rate of the geometric mean diameter (GMD) and the increase margin of GMD are proportional to the initial particle number concentration (PNC) and the environmental temperature. When the relative humidity or the fuel sulfur content is higher, the larger increase margin of the GMD appears, but the increase rate of GMD is not affected obviously. Moreover, the initial PNC gives nearly no contributions to the diffusion range. The initial GMD also shows no markedly effects on the decrease rate of the volume concentration. The fuel sulfur content could affect the PNC distribution in a larger region of the flow field, while the environmental relative humidity and temperature have no evident effects on the distribution range of the PNC.

中文翻译:

汽车尾气超细颗粒物多动力学行为演化数值研究

摘要 在这项研究中,通过数值研究来模拟柴油车尾气中超细颗粒物的演化过程。泰勒矩展开法(TEMOM)-CFD耦合模型主要应用于非球形粒子,同时模拟混凝、沉积、凝结和成核四种粒子动力学行为。与之前的模拟研究相比,开发的模型显示出更接近实验数据的结果。系统分析了初始粒子数、初始粒子大小、环境温度、相对湿度、燃料含硫量和排气速度对演化过程的影响。结果表明,几何平均直径(GMD)的增加率和GMD的增加幅度与初始粒子数浓度(PNC)和环境温度成正比。当相对湿度或燃料含硫量较高时,GMD的增加幅度出现较大,但对GMD的增加率影响不明显。此外,初始 PNC 对扩散范围几乎没有贡献。初始 GMD 对体积浓度的下降率也没有显着影响。燃料硫含量会影响流场较大区域的PNC分布,而环境相对湿度和温度对PNC的分布范围没有明显影响。当相对湿度或燃料含硫量较高时,GMD的增加幅度出现较大,但对GMD的增加率影响不明显。此外,初始 PNC 对扩散范围几乎没有贡献。初始 GMD 对体积浓度的下降率也没有显着影响。燃料硫含量会影响流场较大区域的PNC分布,而环境相对湿度和温度对PNC的分布范围没有明显影响。当相对湿度或燃料含硫量较高时,GMD的增加幅度出现较大,但对GMD的增加率影响不明显。此外,初始 PNC 对扩散范围几乎没有贡献。初始 GMD 也没有显示出对体积浓度下降率的显着影响。燃料硫含量会影响流场较大区域的PNC分布,而环境相对湿度和温度对PNC的分布范围没有明显影响。初始 GMD 对体积浓度的下降率也没有显着影响。燃料硫含量会影响流场较大区域的PNC分布,而环境相对湿度和温度对PNC的分布范围没有明显影响。初始 GMD 对体积浓度的下降率也没有显着影响。燃料硫含量会影响流场较大区域的PNC分布,而环境相对湿度和温度对PNC的分布范围没有明显影响。
更新日期:2021-01-01
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