基于数值计算的细颗粒物采样管路传输损失评估

发布时间：2018-05-30 19:08

本文选题：细颗粒物 + 采样管路　；参考：《环境科学》2016年12期

【摘要】：细颗粒物(PM_(2.5))理化性质测量是研究大气PM_(2.5)污染来源及成因的重要手段之一,最大限度降低细颗粒物在采样输送过程中的损失对提高测量结果的准确性至关重要.为了评估常规测量体系中采样管路内PM_(2.5)的输送损失情况,并在此基础上探究合适的采样管路布置方案,本研究采用数值计算方法分析了管径、管长及弯管数目这3个主要参数在不同变化范围内对PM_(2.5)输送效率的影响.结果表明,流量为20.0 L·min~(-1)时,管径4 mm、管长1.0 m的竖直管路内PM_(2.5)质量浓度输送效率为89.6%,管径增至14 mm时输送效率升至98.3%.流量为1.0 L·min~(-1)时,管径4 mm、管长10.0 m的水平管路内PM_(2.5)质量浓度输送效率仅为86.7%,管长降至0.5 m时输送效率提高至99.2%.弯管弧度为90°时,流量20.0 L·min~(-1)、管径4 mm的湍流态弯管处,PM_(2.5)质量浓度输送效率低至85.2%.流量(L·min~(-1))与管径(mm)之比小于1.4使管内流态为层流时有利于降低颗粒物输送损失.为保证PM_(2.5)输送效率在97%以上,2.5、5.0和10.0 L·min~(-1)仪器建议选择管长在6.0 m以内的竖直采样管;流量为16.7 L·min~(-1)和20.0 L·min~(-1)仪器建议选择管径在12 mm以上的竖直采样管;水平管路管长由流量与管径之比确定;在湍流流态下,建议减少弯管的使用数量.
[Abstract]:The measurement of physical and chemical properties of fine particulate matter is one of the important means to study the source and cause of atmospheric PMmatter pollution. It is very important to reduce the loss of fine particulate matter in the process of sampling and transportation to improve the accuracy of measurement results. In order to evaluate the transportation loss of PMSP 2.5) in the conventional measurement system, and on this basis to explore the appropriate layout of the sampling pipeline, the diameter of the pipe is analyzed by numerical calculation method. The influence of three main parameters of pipe length and number of bends on the transport efficiency of PMCs 2.5 in different ranges. The results show that when the flow rate is 20.0 L / min ~ (-1), the transport efficiency of mass concentration in a vertical pipe with a diameter of 4 mm and a length of 1.0 m is 89.6m, and when the diameter of the pipe increases to 14 mm, the transport efficiency increases to 98.3mm. When the flow rate is 1.0 L / min ~ (-1), the transport efficiency of mass concentration in a horizontal pipe with a diameter of 4 mm and a length of 10.0 m is only 86.7% and 99.2% when the length of the pipe drops to 0.5 m. When the curve is 90 掳, the mass concentration transport efficiency is as low as 85.2 when the flow rate is 20.0 L / min ~ (-1) and the pipe diameter is 4 mm. When the flow rate is less than 1.4, the laminar flow pattern is favorable to reduce the particle transport loss. In order to ensure that the transport efficiency is over 97% and 10.0 L / min ~ (-1), it is suggested that a vertical sampling tube with a length of less than 6.0 m should be selected, and a vertical sampling tube with a flow rate of 16.7 L / min ~ (-1) and 20.0 L / min ~ (-1) should be selected. The length of the horizontal pipe is determined by the ratio of flow to diameter, and it is suggested to reduce the number of bends in turbulent flow.
【作者单位】：上海交通大学环境科学与工程学院;北京科领奈尔环境科技有限公司;上海市环境科学研究院;
【基金】：国家科技支撑计划项目(2014BAC22B01) 国家重点研发计划项目(2016YFC0208700)
【分类号】：X513;X831

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