Theoretical and experimental analysis of the core sampling method: Reducing diffusional losses in aerosol sampling line
收藏Taylor & Francis Group2019-12-09 更新2026-04-16 收录
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Core sampling method (extracting a portion of a flow from the core of the flow) will reduce diffusional losses of highly diffusive species (e.g., aerosol nanoparticles, ions, and gases) when transporting them through a sampling tube. Revealing parameters governing the sampling efficiency of a core sampling system, <i>η</i><sub>sam</sub>, helps to design the apparatus and to optimize its performance. In this study, we report an analytical solution for quantifying the <i>η</i><sub>sam</sub> by solving the convection diffusion equation of laminar flow field. The analytical results were experimentally evaluated using 1–5 nm tungsten oxide nanoparticles. <i>η</i><sub>sam</sub> is governed by a dimensionless loss parameter and the transport-to-sample flow ratio. Theoretically predicted values for <i>η</i><sub>sam</sub> agree with experimental results, e.g., the relative deviation is within 5% when the value for the loss parameter is less than 0.1. The core sampling method is recommended to work at the loss parameter less than 0.1 such that <i>η</i><sub>sam</sub> is equal or close to the maximum value of unity and is also insensitive to variations in sampling conditions. In this study, how to apply the findings in designing and optimizing a core sampling system was discussed. A core sampling apparatus was then designed and experimentally evaluated. Its sampling efficiency was shown to be significantly higher than those of a tee, a cross fitting, and a Y fitting when the same sampling conditions were used. Copyright © 2019 American Association for Aerosol Research
核心采样法（core sampling method）指从流场核心提取部分气流，该方法在通过采样管输送高扩散性物质（例如气溶胶纳米颗粒、离子与气体）时，可降低此类物质的扩散损失。阐明调控核心采样系统采样效率（η_sam）的参数，可为装置设计与性能优化提供支撑。本研究通过求解层流流场的对流扩散方程，给出了可量化η_sam的解析解。研究采用1~5 nm的氧化钨纳米颗粒对解析结果开展了实验验证。η_sam由无量纲损失参数与输送-采样流量比共同决定。当损失参数小于0.1时，η_sam的理论预测值与实验结果吻合良好，相对偏差不超过5%。建议核心采样法在损失参数小于0.1的条件下运行，此时η_sam可达或接近最大值1，且不受采样工况波动的显著影响。本研究探讨了如何将研究成果应用于核心采样系统的设计与优化。在此基础上设计了一套核心采样装置并开展实验评估。在相同采样工况下，该装置的采样效率显著高于三通、四通与Y型接头采样装置。版权所有©2019 美国气溶胶研究协会（American Association for Aerosol Research）
提供机构：
Yueyun Fu; Runlong Cai; Jingkun Jiang
创建时间：
2019-12-09
