Relationship between Particle Mass and Mobility for Diesel Exhaust Particles

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• 作者：Kihong Park ; Feng Cao ; David B. Kittelson ; and Peter H. McMurry
• 刊名：Environmental Science & Technology
• 出版年：2003
• 出版时间：February 1, 2003
• 年：2003
• 卷：37
• 期：3
• 页码：577 - 583
• 全文大小：236K
• 年卷期：v.37,no.3(February 1, 2003)
• ISSN：1520-5851

文摘

We used the aerosol particle mass analyzer (APM) tomeasure the mass of mobility-classified diesel exhaustparticles. This information enabled us to determine theeffective density and fractal dimension of diesel particlesas a function of engine load. We found that the effectivedensity decreases as particle size increases. TEM imagesshowed that this occurs because particles becomemore highly agglomerated as size increases. Effectivedensity and fractal dimension increased somewhat asengine load decreased. TEM images suggest that this occursbecause these particles contain more condensed fuel and/or lubricating oil. Also, we observed higher effectivedensities when high-sulfur EPA fuel (~360 ppm S) wasused than for Fischer-Tropsch fuel (~0 ppm S). In addition,the effective density provides the relationship betweenmobility and aerodynamic equivalent diameters. Therelationship between these diameters enables us tointercompare, in terms of a common measure of size,mass distributions measured with the scanning mobilityparticle sizer (SMPS) and a MOUDI impactor without makingany assumptions about particle shape or density. Weshow that mass distributions of diesel particles measuredwith the SMPS-APM are in good agreement withdistributions measured with a MOUDI and a nano-MOUDIfor particles larger than ~60 nm. However, significantlymore mass and greater variation were observed by the nano-MOUDI for particles smaller than 40 nm than by the SMPS-APM.