Development of a sharp-cut cyclone for ambient aerosol monitoring applications
Development of a sharp-cut cyclone for ambient aerosol monitoring applications
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DOI：
10.1080/027868200303669
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发表时间：
2000-04-01
影响因子：
5.2
通讯作者：
Meyer, M
中科院分区：
文献类型：
--
作者：
Kenny, LC;Gussmann, R;Meyer, M
用于环境PM2.5的气溶胶采样器需要具有陡峭的空气动力学粒度选择曲线，即，空气动力学直径为2.5 μ m的“锐切口”。对于长期和连续的PM监测器，选择器系统还需要低维护和在高负载下运行的能力。虽然使用基于冲击器的选择器更容易实现锋利的切割，但使用旋风分离器更容易满足其他要求。针对这些标准测试了四种替代PM2.5选择器：两种是预先存在的商业设计，两种是新型旋风原型。本研究的主要目的是评估选择器在清洁和不同负载条件下的特性，在实验室和现场条件下测试了PM2.5选择器在负载前后的空气动力学尺寸选择特性。气溶胶渗透测量使用空气动力学粒度仪。对两个井冲击器96（WIN）样本、两个新型锐切旋风分离器（SCC）样本、GK旋风分离器系列（GK4.39）的一个成员和一个大学研究玻璃器皿（URG）旋风分离器进行了多次重复试验。在实验室中使用窄级氧化铝粉尘进行了四次负载的氧化铝和SCC。每次加载后测量穿透曲线。五个累积的室外负荷，设置了四个PM2.5采样器，两个与空气净化器和两个与SCC，在夏季的郊区花园。在采样时间范围为96至132 h后，每周测量渗透曲线。三个进一步的累积负荷进行了测试，在一个类似的实验中，在市中心的地下停车场清洁时，所有三个PM2.5尺寸选择器被证明有50%的渗透（D-50）值接近2.5 μ m，虽然渗透曲线形状不同的三个选择器的设计。在加载条件下，双金属和SCC的D-50值均下降，其中双金属的下降幅度最大。在高负荷下，SCC D-50降至2.35 μ m，SCC D-50降至2.15 μ m。SCC旋风分离器为环境空气采样应用提供了一个急剧的切割，其受负载的影响小于SCC旋风分离器。此外，SCC是一种干式系统，而ESTA使用的是含油基材。虽然在24或96小时采样期间，SCC临界点不太可能偏移到不可接受的程度，但在延长的采样期间，其表现不如SCC。
Aerosol samplers for ambient PM2.5 are required to possess a steep aerodynamic particle size selection curve, i.e., a 'sharp cut' at 2.5 mu m aerodynamic diameter. For long-term and continuous PM monitors the selector system also requires low maintenance and the ability to operate at high loadings. While a sharp cut is easier to achieve with an impactor-based selector, the other requirements are more easily met with a cyclone. Four alternative PM2.5 selectors were tested against these criteria: two were pre-existing commercial designs and two were novel cyclone prototypes. The main aim of the work was to assess the characteristics of the selectors when clean and under various loading conditions.The aerodynamic size-selection characteristics of the PM2.5 selectors were tested before and after loading,vith dust, under both laboratory and field conditions. Aerosol penetration measurements were made using an Aerodynamic Particle Sizer. Many repeat tests were performed on two specimens of the Well Impactor Ninety-Six (WINS), two specimens of a novel Sharp-Cut Cyclone (SCC), one member of the GK cyclone family (GK4.39), and one University Research Glassware (URG) cyclone. Four loadings of the WINS and SCC were made in the laboratory using a narrow-fraction alumina dust. The penetration curves were measured after each loading. Five cumulative outdoor loadings were made by setting up four PM2.5 samplers, two with the WINS and two with the SCC, in a suburban garden during the summer months. The penetration curves were measured at weekly intervals after sampling times ranging from 96 to 132 h. Three further cumulative loadings were tested in a similar experiment in a city-center underground car park When clean, all three PM2.5 size selectors were shown to have 50% penetration (D-50) values close to 2.5 mu m, although the penetration curve shape differs for the three selector designs. Under loading the D-50 value for both the WINS and SCC fell, with the decrease being largest for the WINS. With high loadings the SCC D-50 fell to 2.35 mu m and the WINS D-50 fell to 2.15 mu m. The WINS deviation was large enough to potentially lead to ender sampling of PM2.5.The SCC cyclone was seen to provide a sharp cut for ambient air sampling applications that is less affected than the WINS by loading. Additionally, the SCC is a dry system whereas the WINS uses an oiled substrate. While the WINS cut point is unlikely to shift to an unacceptable degree during 24 or 96 h sampling periods, it would perform less well than the SCC over extended sampling periods.