Determination of particle mass, effective density, mass–mobility exponent, and dynamic shape factor using an aerodynamic aerosol classifier and a differential mobility analyzer in tandem

Tavakoli, Farzan; Olfert, Jason S.

doi:10.1016/j.jaerosci.2014.04.010

Cited by 77 publications

(55 citation statements)

References 22 publications

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“…The evidence considered comes from a review of published data of effective density and primary particle size measurements from dozens of combustion sources and operating conditions. The effective density (or mass-mobility relationship) of soot particles can be determined using a tandem arrangement of two out of a possible three different instruments: a mobility classifier (e.g., differential mobility analyzer), a mass classifier (e.g., centrifugal particle mass analyzer (CPMA) or aerosol particle mass analyzer); or an inertial classifier (e.g., electrical low pressure impactor or aerodynamic aerosol classifier) as shown, for example, by McMurry et al (2002), Maricq and Xu (2004), Olfert, Symonds, and Collings (2007), and Tavakoli and Olfert (2014). Aggregate and primary particle size can be obtained from TEM analysis of samples that have been thermophoretically or electrostatically deposited on thin films.…”

Section: Methodsmentioning

confidence: 99%

Universal relations between soot effective density and primary particle size for common combustion sources

Olfert

Rogak

2019

Aerosol Science and Technology

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Section: Methodsmentioning

confidence: 99%

Universal relations between soot effective density and primary particle size for common combustion sources

Olfert

Rogak

2019

Aerosol Science and Technology

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“…Water-soluble ions were measured by the Monitor for AeRosol and Gases (MARGA; ten Brink et al, 2007). Both instruments are equipped with a PM 2.5 inlet to remove the coarse particles …”

Section: Ambient Measurementsmentioning

confidence: 99%

“…Due to the spherical assumption of the BC core, a constant particle density is adopted for simplicity instead of size-dependent particle density. But it is worth noting that in reality, the effective density of soot varies with particle size due to the morphology change during particle aging (Tavakoli and Olfert, 2014;Dastanpour et al, 2017). Both core diameters (D core ) and shell diameters (D shell ) are constrained in the range of ∼10-3000 nm in the model simulations.…”

Section: Mie Simulationmentioning

confidence: 99%

Quantifying black carbon light absorption enhancement with a novel statistical approach

Wang

2018

Atmos. Chem. Phys.

103

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Abstract. Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, E abs , was quantified using a 1-year measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAE p ), the key for E abs estimation, is demonstrated using the minimum R squared (MRS) method, exploring the inherent source independency between BC and its coating materials. A unique feature of E abs estimation with the MRS approach is its insensitivity to systematic biases in elemental carbon (EC) and σ abs measurements. The annual average E abs550 is found to be 1.50±0.48 (±1 SD) in the PRD region, exhibiting a clear seasonal pattern with higher values in summer and lower in winter. Elevated E abs in the summertime is likely associated with aged air masses, predominantly of marine origin, along with long-range transport of biomassburning-influenced air masses from Southeast Asia. Coreshell Mie simulations along with measured E abs and absorption Ångström exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than in the dry season.

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“…where D f is the mass-mobility exponent (Tavakoli and Olfert 2014). For Engine 1, the fractal dimension was 2.28, and that of Engine 2 was 2.34.…”

Section: Performance Testsmentioning

confidence: 99%

“…Van Gulijk et al (2004) also used a DMA and an ELPI and verified that the estimated mobility diameter based on the aerodynamic diameter gave a better indication of the apparent particle size compared to the results of aerodynamic particle size analysis based on scanning electron microscopy (SEM). In addition, Tavakoli and Olfert (2014) classified the aerodynamic diameter using an aerodynamic aerosol classifier and then measured the mobility diameter of the classified particles with a DMA. The effective density was obtained with the mobility diameter and the corresponding aerodynamic diameter.…”

Section: Introductionmentioning

confidence: 99%

Design and Performance Test of a Lab-Made Single-Stage Low-Pressure Impactor for Morphology Analysis of Diesel Exhaust Particles

Hyun

Nasr

Choi³

et al. 2015

Aerosol Science and Technology

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A serial method is described for estimating the particle effective density and dynamic shape factor of particles, i.e., diesel exhaust particles (DEPs). For this purpose, we designed a single stage low-pressure impactor with a cutoff diameter of 130 nm. The collection efficiency curve of the impactor was obtained using mobility-classified sodium chloride (NaCl) particles as a function of the mobility diameter. Then by converting the mobility diameter of the NaCl particle into the aerodynamic equivalent diameter, the efficiency curve can be expressed as a function of the aerodynamic diameter. We also obtained the efficiency curve numerically by using a commercial computational fluid dynamics software package. After confirming the design and performance of the impactor (experimentally 135 nm and numerically 137 nm of cutoff diameter), we measured the currents carried by mobility-classified DEPs downstream and upstream of the impactor so that the collection efficiency value for DEP could be obtained at each mobility diameter of DEPs. By making this value equal to that of the efficiency curve, the relationship between the mobility diameter of DEPs and the aerodynamic diameter was obtained; this enabled us to determine the effective density and dynamic shape factor of DEPs. The effective density decreased from 1.06 to 0.51 g/cm 3 and the dynamic shape factor increased from 1.28 to 1.64 as the particle size increased from 60 to 105 nm, regardless of the engine type or operating conditions.

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Determination of particle mass, effective density, mass–mobility exponent, and dynamic shape factor using an aerodynamic aerosol classifier and a differential mobility analyzer in tandem

Cited by 77 publications

References 22 publications

Universal relations between soot effective density and primary particle size for common combustion sources

Universal relations between soot effective density and primary particle size for common combustion sources

Quantifying black carbon light absorption enhancement with a novel statistical approach

Design and Performance Test of a Lab-Made Single-Stage Low-Pressure Impactor for Morphology Analysis of Diesel Exhaust Particles

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