Nucleation of Ethylene Glycol Vapor and Growth of Sub-10-nm Particles in Nanoparticle Size Magnifier
Nucleation of Ethylene Glycol Vapor and Growth of Sub-10-nm Particles in Nanoparticle Size Magnifier
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DOI：
10.1080/02786826.2011.589481
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发表时间：
2011-05
影响因子：
5.2
通讯作者：
E. Ito;T. Seto;Y. Otani;H. Sakurai
中科院分区：
文献类型：
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作者：
E. Ito;T. Seto;Y. Otani;H. Sakurai
在一种新开发的名为纳米颗粒放大镜(NanoPSM)的冷凝装置中，研究了乙二醇蒸气在10 nm以下颗粒上的异相成核和均相成核速率。纳米PSM中的饱和度比由进气系统和混合段精确控制，这两个部分是基于Okuyama等人开发的早期颗粒放大镜(PSM)而设计的。(1984)。将迁移率直径小于10 nm的纳米氯化钠颗粒作为异相晶核用于乙二醇蒸气的冷凝反应。利用光学粒子计数器(OPC)的脉冲高度分析来确定激活核的激活效率和生长速率。采用计算机流体动力学(CFD)模拟计算了纳米PSM内气体速度、温度、蒸汽浓度和过饱和度的分布。在冷气溶胶和热水汽的混合边界附近产生环状高过饱和区。通过随后的液滴生长到2μm，4.5nmNaC l粒子的实验激活效率为50%，2nmNaC l粒子的实验激活效率为0.8%。当考虑过饱和的局部轮廓时，实验数据与基于经典Kelvin-Thomson理论的预测的活化效率符合得很好。
We investigated the rates of heterogeneous and homogeneous nucleation of ethylene glycol vapor onto sub-10-nm particles in a newly developed condensation device called nanoparticle size magnifier (NanoPSM). The saturation ratio in the NanoPSM is precisely controlled by vapor-feeding system and mixing section, which are designed based on an earlier particle size magnifier (PSM) developed by Okuyama et al. (1984). Size-classified NaCl nanoparticles smaller than 10 nm in mobility diameter are used as heterogeneous nuclei for the condensation of ethylene glycol vapor. The activation efficiency and growth rate of the activated nuclei are determined by a pulse height analysis using an optical particle counter (OPC). A computer fluid dynamics (CFD) simulation is employed to calculate the profiles of the gas velocity, temperature, vapor concentration, and resulting supersaturation in the NanoPSM. Annular high-supersaturation region is generated around the mixing boundary between cold aerosol and hot vapor. The experimental activation efficiency is 50% for 4.5-nm and 0.8% for 2 nm NaCl particles, through the subsequent growth of droplets to 2 μm in diameter. The experimental data are in fairly good agreement with the predicted activation efficiencies based on the classical Kelvin-Thomson theory when the local profiles of supersaturation are taken into account.