Sampling Conditions for the Measurement of Nucleation Mode Particles in the Exhaust of a Diesel Vehicle
Sampling Conditions for the Measurement of Nucleation Mode Particles in the Exhaust of a Diesel Vehicle
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DOI：
10.1080/027868290891497
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发表时间：
2004-01
影响因子：
5.2
通讯作者：
Urs Mathis;J. Ristimäki;M. Mohr;J. Keskinen;L. Ntziachristos;Z. Samaras;P. Mikkanen
中科院分区：
文献类型：
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作者：
Urs Mathis;J. Ristimäki;M. Mohr;J. Keskinen;L. Ntziachristos;Z. Samaras;P. Mikkanen
一种新型的多孔管稀释器的特点是定义采样参数的可重复测量的成核模式粒子（NMP）在现代柴油乘用车在中等发动机负荷的排气。这种多孔管稀释器允许在很宽的范围内独立地改变取样参数。我们研究了采样参数：初级稀释温度（PDT; 15-55 ℃）、初级稀释比（PDR; 8-45）、停留时间（RT; 0.5-4.0 s）和初级稀释的相对湿度（PRH; 5-90%）。减少PDT和增加PRH导致的成核模式中的颗粒数量和尺寸的增长。虽然在20和30之间的中等PDR处发现NMP的最大数量，但在低于20的PDR处实现NMP的最大体积。凝血解释了在RT延长和PDR降低的采样条件下NMP数量的减少。然而，成核模式的尺寸增长只能部分归因于凝聚，因此，由于有机化合物的排气增长可能起着重要的作用。灵敏度分析作为PDR-PDT的函数进行，并揭示了两个最佳的采样条件，可重复的NMP的数量或可重复的最大NMP的体积。除采样参数外，发现排气管线调节会强烈影响NMP，因此需要进行控制，以尽量减少对测量历史的影响。
A novel porous tube diluter was characterized to define sampling parameters for repeatable measurements of nucleation-mode particles (NMPs) in the exhaust of a modern diesel passenger car at moderate engine load. This porous tube diluter permits the variation of sampling parameters independently and in a wide range. We investigated the sampling parameters: primary dilution temperature (PDT; 15–55°C), primary dilution ratio (PDR; 8–45), residence time (RT; 0.5–4.0 s), and relative humidity of primary dilution (PRH; 5–90%). Decreased PDT and increased PRH led to a growth of particle number and size in the nucleation mode. While a maximum number of NMPs was found at moderate PDRs between 20 and 30, a maximum volume of NMPs was achieved at PDRs below 20. Coagulation explains the number reduction of NMPs under sampling conditions of prolonged RT and decreased PDR. However, the size growth of the nucleation mode can only partly be attributed to coagulation, and thus growth due to organic compounds from the exhaust probably plays an important role. Sensitivity analysis was conducted as a function of PDR-PDT and revealed two optimal sampling conditions for repeatable NMPs in number or repeatable maximum NMPs in volume. In addition to the sampling parameters, exhaust line conditioning was found to affect NMPs strongly and thus needs to be controlled to minimize effects on the history of measurements.