Horender Stefan, Auderset Kevin, Vasilatou Konstantina
Laboratory Particles and Aerosols, Federal Institute of Metrology METAS, Lindenweg 50, 3003 Bern-Wabern, Switzerland.
Rev Sci Instrum. 2019 Jul;90(7):075111. doi: 10.1063/1.5095853.
In this study, we present a custom-made facility developed for evaluating the measurement efficiency of optical particle counters and other common aerosol instrumentation. The facility consists of an aerosol generation setup, a turbulent flow tube for particle homogenization, isokinetic sampling ports, and a home-built particle counter that serves as a reference instrument. Stable and reproducible aerosols of polystyrene latex particles can be produced in the size range 100 nm-10 μm and at concentrations between 0.5 cm and a few thousand submicron particles per cm or a few tens of 10 µm particles per cm. The flow characteristics in the homogenizer were investigated with laser Doppler velocimetry measurements and computational fluid dynamics simulations indicating a plug (turbulent) flow at the aerosol sampling location. The particle mixing characteristics were determined experimentally at various heights of the flow tube by parallel measurements with two condensation particle counters. A spatial homogeneity within 1.1% was found across the sampling area. The measurement uncertainties in the determination of the particle number concentration have been evaluated in detail and amount typically to 5.4% at 1 cm and 2.1% at 100 cm (95% confidence level).
在本研究中，我们展示了一种为评估光学粒子计数器和其他常见气溶胶仪器的测量效率而开发的定制设备。该设备包括一个气溶胶生成装置、一个用于粒子均匀化的湍流管、等速采样口以及一个作为参考仪器的自制粒子计数器。可以产生尺寸范围在100纳米至10微米、浓度在每立方厘米0.5个至数千个亚微米粒子或每立方厘米几十个10微米粒子之间的稳定且可重现的聚苯乙烯乳胶粒子气溶胶。通过激光多普勒测速测量和计算流体动力学模拟研究了均化器中的流动特性，结果表明在气溶胶采样位置为塞流（湍流）。通过使用两个凝结核粒子计数器进行平行测量，在流动管的不同高度上通过实验确定了粒子混合特性。在整个采样区域内发现空间均匀性在1.1%以内。已经详细评估了粒子数浓度测定中的测量不确定度，在1厘米处通常为5.4%，在100厘米处为2.1%（95%置信水平）。
