Theoretical Investigation of Volatile Removal Efficiency of Particle Number Measurement Systems
Theoretical Investigation of Volatile Removal Efficiency of Particle Number Measurement Systems
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DOI：
10.4271/2010-01-1304
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发表时间：
2010-01-01
影响因子：
1.2
通讯作者：
Drossinos, Yannis
中科院分区：
文献类型：
--
作者：
Giechaskiel, Barouch;Drossinos, Yannis
欧5/6轻型汽车排放法规引入了非挥发性颗粒物数量排放测量。颗粒数测量系统由挥发物去除单元和颗粒数计数器组成，颗粒数计数器的50%截点直径为23 nm。对于粒径大于30 nm、入口浓度大于10（4）cm（-3）的单分散气溶胶，挥发物去除装置必须使其浓度降低99%以上。讨论了蒸发管中的温度和停留时间，以及蒸发颗粒在蒸发管出口处成核事件的可能性。此外，还对蒸发管出口处的硫酸成核进行了分析。最后，将理论计算与实验数据进行了比较，得出的主要结论是，该方法可以很容易地满足法规对挥发物去除效率的要求。然而，正如一些实验测量所示，对于大颗粒尺寸和高浓度，去除效率可能会有所不同;因此，应谨慎解释50%截点直径小于23 nm的颗粒计数器的结果。
Euro 5/6 light-duty vehicle emissions regulation introduced non-volatile particle number emission measurements. The particle number measurement system consists of a volatile removal unit followed by a particle number counter with a 50% cut-point diameter at 23 nm. The volatile removal unit must achieve a >99% concentration reduction of a monodisperse aerosol of tetracontane ( CH (3)(CH (2)) 38CH (3)) particles of diameter >= 30 nm with inlet concentration >= 10 (4) cm (-3).In this paper the evaporation of tetracontane particles in the volatile removal unit is investigated theoretically. The temperature and the residence time in the evaporation tube are discussed, as well as the possibility of nucleation events of evaporated particles at the exit of the evaporation tube. In addition, sulfuric acid nucleation at the evaporation tube exit is analyzed. Theoretical calculations are, finally, compared to experimental data.Our main conclusion is that the volatile removal efficiency requirements of the legislation can be easily met. However, as some experimental measurements showed, the removal efficiency might differ for large particle sizes and high concentrations; thus, the results of particle number counters with a 50% cut-point diameter less than 23 nm should be interpreted with care.