Influence of chemical reactions and turbulent diffusion on the formation of local pollutant concentration distributions
Influence of chemical reactions and turbulent diffusion on the formation of local pollutant concentration distributions
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DOI：
10.1016/j.buildenv.2019.106487
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发表时间：
2020-01-01
影响因子：
7.4
通讯作者：
Ito, Kazuhide
中科院分区：
文献类型：
--
作者：
Lim, Eunsu;Chung, Juyeon;Ito, Kazuhide
在过去的几十年里，人们一直在研究室内环境中污染物浓度非均匀分布的结构形成机制，以确定有效的通风设计。本文基于计算流体力学技术，对室内局部污染物浓度分布进行了数值分析。特别是，气相化学反应和湍流扩散的局部污染物浓度的形成的影响进行了参数化分析，并定量研究结构的通风效率的指标，即净逃逸速度（NEV）的概念。NEV概念代表了实质性的速度尺度，结合了污染物在某一点的平流和扩散速度，并作为确定该点污染物浓度的指标。通过对第一Damk_ohler数Da和湍流施密特数Sct的敏感性分析，发现Sct对污染物浓度分布的影响比Da更显著，当Sct从0.5变化到1.0时，NEV显著增加，尤其是在滞流区，这可能是由于湍流扩散和对流作用提高了污染物的排放效率。因此，新能源汽车可以用来定量评估污染物浓度的变化伴随着Da或Sct的变化。
The mechanism of structure formation of non-uniform pollutant concentration distributions in indoor environments have been investigated over the past several decades to determine effective ventilation designs. In this study, numerical analyses of local pollutant concentration distributions in indoor environments are performed based on computational fluid dynamics techniques. In particular, the influence of gas phase chemical reactions and turbulent diffusion on the formation of the local pollutant concentration is parametrically analyzed, and the structures are quantitatively investigated using the index for ventilation efficiency, namely the net escape velocity (NEV) concept. The NEV concept represents the substantive velocity scale, combining advection and diffusion velocity of pollutant at a point, and functions as an index to determine the pollutant concentration at that point. Sensitivity analyses as functions of the first Damk_ohler number (Da) and the turbulent Schmidt number (Sct) were performed, and the influence of Sct on pollutant concentration distributions was more significant compared with that of Da. When Sct was changed from 0.5 to 1.0, the significant NEV increase, especially that in the stagnant flow region, could be attributed to the enhanced pollutant discharge efficiency due to turbulent diffusion in addition to convective flow. Thus, NEV could be used to quantitatively assess the changes in pollutant concentrations accompanying the change in Da or Sct.