Fine particle losses in electrical low-pressure impactor

Virtanen, Annele; Marjamäki, Marko; Ristimäki, Jyrki; Keskinen, Jorma

doi:10.1016/s0021-8502(00)00087-2

Cited by 82 publications

(50 citation statements)

References 10 publications

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“…The presence of bounce, therefore, generates an erroneously high raw current in the lower stages (i.e., larger particles are mistakenly counted as smaller particles). Raw currents are subject to a correction algorithm, which corrects for diffusion and space charger losses [49,50].…”

Section: Bounce Analysismentioning

confidence: 99%

The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State

2018

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Absolute secondary organic aerosol (SOA) mass loading (C SOA ) is a key parameter in determining partitioning of semi-and intermediate volatility compounds to the particle phase. Its impact on the phase state of SOA, however, has remained largely unexplored. In this study, systematic laboratory chamber measurements were performed to elucidate the influence of C SOA , ranging from 0.2 to 160 µg m −3 , on the phase state of SOA formed by ozonolysis of various precursors, including α-pinene, limonene, cis-3-hexenyl acetate (CHA) and cis-3-hexen-1-ol (HXL). A previously established method to estimate SOA bounce factor (BF, a surrogate for particle viscosity) was utilized to infer particle viscosity as a function of C SOA . Results show that under nominally identical conditions, the maximum BF decreases by approximately 30% at higher C SOA , suggesting a more liquid phase state. With the exception of HXL-SOA (which acted as the negative control), the phase state for all studied SOA precursors varied as a function of C SOA . Furthermore, the BF was found to be the maximum when SOA particle distributions reached a geometric mean particle diameter of 50-60 nm. Experimental results indicate that C SOA is an important parameter impacting the phase state of SOA, reinforcing recent findings that extrapolation of experiments not conducted at atmospherically relevant SOA levels may not yield results that are relevant to the natural environment.

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Section: Bounce Analysismentioning

confidence: 99%

The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State

2018

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“…It should be noted that number distribution is not calculated from measured currents at any point, but instead a mathematical model of ELPI is used. The complete set of information required to construct the mathematical model of ELPI, can be found from Marjamäki et al (2000Marjamäki et al ( , 2005 and Virtanen et al (2001).…”

Section: Methods For Estimating Particle Densitymentioning

confidence: 99%

Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki

et al. 2006

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Abstract. Number concentrations and size distributions of traffic related aerosol particles were measured at a roadside in Helsinki during two winter campaigns (10-26 February 2003, 28 January-12 February 2004 and two summer campaigns (12-27 August 2003, 6-20 August 2004. The measurements were performed simultaneously at distances of 9 m and 65 m from the highway. Total number concentrations were measured by a condensation particle counter (CPC) and particle size distributions by a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). This study concentrates on data that were measured when the wind direction was from the road to the measurement site. The total concentrations in the wintertime were 2-3 times higher than in the summertime and the concentrations were dominated by nucleation mode particles. The particles smaller than 63 nm (aerodynamic diameter) constituted ∼90% of all particles in the wintertime and ∼80% of particles in the summer time. The particle total concentration increased with increasing traffic rate. The effect of traffic rate on particles smaller than 63 nm was stronger than on the larger particles. The particle distributions at the roadside consisted of two distinguishable modes. The geometric mean diameter (GMD) of nucleation mode (Mode 1) was 20.3 nm in summer and 18.9 nm in winter. The GMD of the larger mode consisting mostly of traffic related soot particles (Mode 2) was 72.0 nm in summer and 75.1 nm in winter. The GMD values of the modes did not depend on the traffic rate. The average particle density for each mode was determined by a parallel density fitting method based on the size distribution measurement made by ELPI and SMPS. The average density value for Mode 1 particles Correspondence to: A. Virtanen (annele.virtanen@tut.fi) was 1.0±0.13 g/cm 3 and 1.0±0.07 g/cm 3 both in summer and winter respectively, while the average density value for Mode 2 was 1.5±0.1 g/cm 3 and 1.8±0.3 g/cm 3 for summer and winter, respectively.

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“…The remaining three are interfering loss mechanisms that hamper accurate size distribution measurements. Fortunately these losses are generally small and can be corrected for, as described by Virtanen et al (2001) and Marjmäki et al (2005), and discussed further in the following section. These corrections are implemented in the ELPI software, but they require information on the particle density, usually assumed to equal unity.…”

Section: Elpi Backgroundmentioning

confidence: 99%

Measuring Particulate Mass Emissions with the Electrical Low Pressure Impactor

Maricq

Chase

2006

Aerosol Science and Technology

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The electrical low pressure impactor (ELPI) is a useful tool for recording transient particle size distributions, such as in motor vehicle emissions. But for sub-micron aerosols, the straightforward mass weighting and integration of these size distributions overestimates the particulate matter (PM) mass by a factor of two or more. The present article examines the sources of this discrepancy and develops an analysis that allows quantitative PM mass measurement with an accuracy of about 20%. This procedure is applied to measure motor vehicle PM emissions, and the results are compared with filter-based gravimetric determinations. Good agreement is achieved for diesel and direct injection gasoline vehicles. For particulate trap equipped diesel vehicles and conventional gasoline vehicles, the PM mass recorded by the ELPI is often substantially lower than the filter based mass owing to the gaseous adsorption artifact of the latter. Accurate work at very low emissions levels, less than ∼1 mg/mi, requires further study of how reliably the ELPI can provide semivolatile nanoparticle mass as well as an improved understanding of filter-based vehicle exhaust measurement.

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Fine particle losses in electrical low-pressure impactor

Cited by 82 publications

References 10 publications

The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State

The Influence of Absolute Mass Loading of Secondary Organic Aerosols on Their Phase State

Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki

Measuring Particulate Mass Emissions with the Electrical Low Pressure Impactor

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