摘要
为满足环境气溶胶在线进样的要求,改善电感耦合等离子体质谱计(Inductively Coupled Plasma Mass Spectrometry,ICP蛳MS)对粒子中待测核素的探测限,研制出一套具有低流量、低压降特点的狭缝虚拟撞击器,可作为气溶胶在线富集进样系统的关键部件与ICPˉMS联用。本文介绍了该狭缝虚拟撞击器的研制情况:首先由ICP蛳MS的进样条件,根据经验公式完成了理论设计,确定进样流量为11L/min,强流与弱流的流量比为10,喷射狭缝宽度为1mm,长宽比为10;然后用计算流体动力学软件Fluent R对上述结构内部的流场和粒子运动径迹进行了数值模拟,考察了喷射狭缝与收集狭缝的间距G、收集狭缝的宽度Wc及其进口曲率半径的加工偏差对收集效率的影响,得到了较优化的取值范围:G取1.0～1.2mm,Wc取1.4～1.6mm,此时的切割粒径D50约2.5μm;加工出狭缝虚拟撞击器的原型装置,对其分别用室内空气气溶胶和荧光素钠标记的单分散油酸粒子进行富集性能测量。实测结果表明:空气动力学等效直径在2.5～5μm范围内的粒子浓度得到了明显富集,5μm的粒子的富集因子达到极大值7。
Inductively Coupled Plasma Mass Spectrometry （ICP-MS） has potential to be a powerful tool for on-line analysis of radioactive particle. In this paper, a low-flow slit virtual impactor （SVI） used as an aerosol concentrator coupled with ICP-MS was developed and characterized in laboratory. First, based on sampling conditions of ICP-MS, the inlet flow of SVI was set 11 L/min, ratio of major flow to minor flow was 10, width of injection slit was 1 mm and ratio of length to width was 10. Then, a Computational Fluid Dynamics code, Fluent, was used to simulate flow field and track particle trajectory in SVI. Effects of distance between injection slit and collection slit （G）, width of collection slit （Wc）, and curvature of collection slit inlet on collection efficiency of SVI were all evaluated. Optimized ranges of G and Wc were 1.0-1.2 mm and 1.4-1.6 mm respectively, corresponding to a cutpoint of 2.5 micron. A prototype of SVI was manufactured and fabricated. Finally, indoor aerosol and monodisperse oleic acid particle labeled with fluorescein sodium were used to determine the actual enrichment factor （EF） curve of the prototype. Results show that particles in the range of 2.5-5 microns are concentrated obviously and the maximum value of EF is 7 for particle of 5 micron.
出处
《辐射防护》
CAS
CSCD
北大核心
2009年第5期279-288,共10页
Radiation Protection
基金
西北核技术研究所项目(NYS0506)
关键词
ICP-MS
放射性气溶胶
在线富集进样
狭缝虚拟撞击器
ICP-MS, Airborne Radioactive Aerosol, Concentration Enrichment, Low-flow Slit Virtual Impactor
