Can Real-World Diesel Exhaust Particle Size Distribution be Reproduced in the Laboratory? A Critical Review Jorma Keskinen

Keskinen, Jorma; Rönkkö, Topi

doi:10.3155/1047-3289.60.10.1245

Cited by 82 publications

(53 citation statements)

References 70 publications

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“…S9. Real-world nanoparticle formation was mimicked using an exhaust sampling system (40) that has been reported to mimic exhaust nucleation mode particle formation relatively well (29,41). With this sampling system, a portion of exhaust was sampled directly from the tailpipe and further diluted immediately using a porous tube-type primary diluter (42), led through a residence time chamber with a residence time of 2.6 s, and finally diluted by an ejector secondary dilution unit.…”

Section: Methodsmentioning

confidence: 99%

Traffic is a major source of atmospheric nanocluster aerosol

Rönkkö

Kuuluvainen

Karjalainen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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195

132

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In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·10 15 (kg fuel ) −1 in a roadside environment, 2.6·10 15 (kg fuel ) −1 in a street canyon, and 2.9·10 15 (kg fuel ) −1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·10 12 (kg fuel ) −1 to a high value of 4.3·10 15 (kg fuel ) −1 . These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds.nanocluster aerosol | atmospheric aerosol | combustion-derived nanoparticles | air pollution | traffic emission D etailed characterization of aerosol sources is required to understand climate impacts and health effects of atmospheric aerosols, as well as to develop technologies and policies capable of mitigating air pollution in urbanized areas. In densely populated areas, one of the most significant source of particles is traffic (1, 2). Owing to their small size and complicated chemical and physical characteristics (3-6), atmospheric particles resulting from traffic emissions pose a significant risk to human health (7-12), and also contribute to anthropogenic forcing of climate (13,14). Previous research on vehicular emissions has demonstrated the presence of soot and ash (3, 15) and solid sub-10-nm core particles (4-6) in primary emissions from vehicles and engines and their variation, depending on vehicle technologies (4, 6), the properties of fuels and lubricant oils (15, 16), and driving conditions (15-17). In addition to particles, exhaust typically contains species that reside in the gaseous phase in the undiluted high-temperature exhaust (5, 18, 19) but condense or even nucleate to the particle phase immediately after the exhaust is released to the atmosphere. Here, we term such aerosols delayed primary aerosols, because particle precursors exist already in the u...

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Section: Methodsmentioning

confidence: 99%

Traffic is a major source of atmospheric nanocluster aerosol

Rönkkö

Kuuluvainen

Karjalainen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

195

132

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“…Exhaust dilution was conducted using a partial exhaust flow dilution system (Ntziachristos et al, 2004) consisting of a porous tube diluter, a short aging chamber and a secondary diluter. The dilution system has been observed to mimic relatively well the real-world cooling and dilution processes, especially from the viewpoint of exhaust nanoparticle formation (R€ onkk€ o et al, 2006;Keskinen and R€ onkk€ o, 2010). The primary dilution ratios of the porous tube diluter and secondary diluter (Dekati Diluter) were approximately 12 and 4.5, respectively.…”

Section: Experimental Procedures On Chassis Dynamometermentioning

confidence: 96%

Exhaust particles of modern gasoline vehicles: A laboratory and an on-road study

Karjalainen

Pirjola

Heikkilä

et al. 2014

Atmospheric Environment

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156

114

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“…To develop engine strategies that meet very low PM emissions levels, such as CARB's future 1 mg/mi LEV III standard and the EU6 6 £ 10 11 particles/km solid number standard, engineers need time resolved PM measurements that can relate emissions to specific engine and aftertreatment conditions. Size and composition information can also help by distinguishing particles formed in the engine from those related to aftertreatment or exhaust dilution and cooling (Khalek et al 2000;Keskinen and R€ onkk€ o 2010). Tightening regulations for aircraft PM emissions are driving a similar need for improved instrument capability to measure gas turbine exhaust PM (Petzold et al 2011).…”

Section: Introductionmentioning

confidence: 99%

How well can aerosol instruments measure particulate mass and solid particle number in engine exhaust?

Maricq

Szente

Harwell

et al. 2016

Aerosol Science and Technology

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Aerosol instruments provide more informative engine exhaust particulate matter (PM) data than the gravimetric filter and solid particle number methods prescribed by regulations. Yet their lack of conformity to the regulatory methods can limit their acceptance for vehicle development. This article examines the ability of the Dekati Mass Monitor (DMM), Engine Exhaust Particle Sizer (EEPS), and Micro Soot Sensor (MSS) to measure PM 2.5 mass and solid particle number relative to current motor vehicle PM emissions standards. Simultaneous PM measurements are made by these three instruments and the two regulatory methods for 50 tests of six gasoline direct injection and two port fuel injection vehicles over the U.S. Federal Test Procedure. DMM and EEPS determinations of PM mass correlate well to gravimetric values (regression slopes of 1.06 § 0.04 and 0.98 § 0.08) down to a few mg/mile, below which filter weighing variability becomes problematic. The MSS exhibits a lower slope of 0.79 § 0.03 consistent with it measuring the soot fraction, rather than total PM. At emissions rates above »10 13 particles/mile, solid particle number determined from DMM and EEPS data correlates respectably with, but overestimates the regulatory method (regression slopes are 1.7 § 0.1 and 1.4 § 0.15, respectively). Below this emissions rate, the correlation degrades. EEPS estimates of PM mass are significantly improved with the recent soot optimized inversion algorithm (slope improves from 0.45 to 0.98). While they cannot replace filters and solid particle counting, the present study suggests that these instruments can be used as more informative surrogates during motor vehicle development.

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Can Real-World Diesel Exhaust Particle Size Distribution be Reproduced in the Laboratory? A Critical Review Jorma Keskinen

Cited by 82 publications

References 70 publications

Traffic is a major source of atmospheric nanocluster aerosol

Traffic is a major source of atmospheric nanocluster aerosol

Exhaust particles of modern gasoline vehicles: A laboratory and an on-road study

How well can aerosol instruments measure particulate mass and solid particle number in engine exhaust?

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