Abstract

The overall counting performance of two optical particle counters (OPCs), which had a sampling flowrate of 28.3 L/min, was evaluated. An inkjet aerosol generator (IAG) was used to generate at a constant rate monodisperse test particles in the size range of 0.3–10 µm. The effect of particle phase on the counting efficiency (CE) of the two OPCs (RION KC-31 and Lighthouse Solair 1100) was characterized. Lactose monohydrate (LM) and sodium chloride (NaCl) particles were used as the solid particles. The particles of a water-soluble ionic liquid were used as the liquid particles. The CEs were evaluated for polystyrene latex (PSL) particles using a parallel comparison method. The CE of each of the two OPCs measured for solid particles was different from that measured for liquid particles. With liquid particles, the CE decreased over the micrometer range indicating that the particles had deposited on a surface within the OPC. Each CE had a sharp minimum for LM particles when the aerodynamic diameter of the particles, $d_{\mathrm{a}},$ was in the 2.5–2.6 µm range. The probability of particle bounce was evaluated using other experiments, and the results suggested that solid particles whose $d_{\mathrm{a}}$ was in the 2.6–2.9 µm range would bounce off at the inner surface of the focusing segment of the OPC, located upstream of the optical system. The CEs measured when using NaCl and PSL particles were close to unity and did not decrease over a few micrometer range; however, these particles also would bounce off.

Copyright © 2021 American Association for Aerosol Research

摘要

评估了采样流速为 28.3 L/min 的两个光学粒子计数器 (OPC) 的总体计数性能。使用喷墨气溶胶发生器 (IAG) 以恒定速率生成尺寸范围为 0.3-10 µm 的单分散测试颗粒。表征了粒子相对两种 OPC（RION KC-31 和 Lighthouse Solair 1100）计数效率 (CE) 的影响。乳糖一水合物（LM）和氯化钠（NaCl）颗粒用作固体颗粒。水溶性离子液体的颗粒用作液体颗粒。使用平行比较方法评估聚苯乙烯胶乳 (PSL) 颗粒的 CE。对固体颗粒测量的两种 OPC 中的每一种的 CE 与对液体颗粒测量的 CE 不同。与液体颗粒，CE 在微米范围内降低，表明颗粒已沉积在 OPC 内的表面上。当粒子的空气动力学直径为$d_{\mathrm{一种}},$在 2.5–2.6 µm 范围内。使用其他实验评估了粒子反弹的概率，结果表明固体粒子$d_{\mathrm{一种}}$在 2.6-2.9 µm 范围内的 OPC 聚焦段的内表面会反弹，位于光学系统的上游。使用 NaCl 和 PSL 颗粒时测得的 CE 接近统一，并且在几微米范围内没有降低；然而，这些粒子也会反弹。

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