Laboratory Measurements of the Size Distribution and Activation Ratio of Synthetic Ice Nuclei

<p>Laboratory measurement of the particle size distribution and cloud condensation nucleation activation ratio are conducted using two types of synthetic ice nuclei (IN). New Engineered Organic Nuclei (NEON) are fabricated by fermentation and so-called E-lysis of Gram-negative bacteria, which are havested via centrifugation and resuspended in a NaHCO<sub>3</sub> buffer (pH of ~7.8) for final inactivation of lysis escape muntants. NEON is inactivated using 1.25 % (final concentration) glutaraldehyde (GA) and stored in a deep freezer. The NEON with GA solution is atomized using a Sparging Liquid Aerosol Generator (SLAG), which does not sheer or impact the aerosols. The measured size distribution is compared to aerosols produced by the TSI Atmomizer (Model 3076), which impacts generated droplets. The size distribution is measured using a TSI Scanning Mobility Particle Sizer Spectrometer (SMPS) and a TSI Aerodynamic Particle Sizer. A DMT Cloud Condensation Nuclei Counter (CCNC) operated at 0.6 % supersaturation and a TSI Condensation Particle Counter (CPC) is used to measure the activation ratio, which is important to determine effectiveness of the NEON as an immersion ice nuclei. The NEON results are compared to IN produced by burning silver iodine cloud seeding flares.</p>

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Size Distribution of TiO2 Nanoparticles Generated by a Commercial Aerosol Generator for Different Solution Concentrations and Air Flow Rates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.727-728.861 ◽

2012 ◽

Vol 727-728 ◽

pp. 861-866

Author(s):

João Victor Marques Zoccal ◽

Fábio de Oliveira Arouca ◽

José Renato Coury ◽

José Antônio Silveira Gonçalves

Keyword(s):

Size Distribution ◽

Particle Concentration ◽

Air Flow ◽

Industrial Applications ◽

Scanning Mobility Particle Sizer ◽

Flow Rates ◽

Nanoscale Particles ◽

Aerosol Generator ◽

Particle Sizer ◽

Number Of Particles

Advances in scientific research in the field of nanotechnology sparked an increase in technological and industrial applications involving nanoparticles, Moreover, there was increasing concern about the control of nanoscale particles released to the atmosphere, driven by concerns over air quality and human health. In this context, this study aims to determine the size distribution of TiO2nanoparticles generated by the commercial TSI Atomizer Aerosol Generator model 3079 for different solution concentrations and air flow rates. The concentrations of the TiO2solutions used in the generator were 0.0125, 0.025 and 0.05 g.L-1, while the aerosol flow rates were 1.27, 2.55 and 3.82 L.min-1. The size distribution was measured with the TSI Scanning Mobility Particle Sizer (SMPS) equipment, which provides the number of particles per size range. The results showed that even changing the concentration of TiO2in solution, peak concentrations of nanoparticles remained in the same range between 15 to 45 nm. Moreover, it was observed that particle concentration in the gas stream decreased with increasing flow rate.

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Quantifying aerosol size distributions and their temporal variability in the Southern Great Plains, USA

10.5194/acp-2019-131 ◽

2019 ◽

Author(s):

Peter J. Marinescu ◽

Ezra J. T. Levin ◽

Don Collins ◽

Sonia M. Kreidenweis ◽

Susan C. van den Heever

Keyword(s):

Size Distribution ◽

Great Plains ◽

Power Spectral Analysis ◽

Aerosol Size Distribution ◽

Size Distributions ◽

Scanning Mobility Particle Sizer ◽

Condensation Particle Counter ◽

Southern Great Plains ◽

Power Spectral ◽

Particle Sizer

Abstract. A quality-controlled, 5-year dataset (2009–2013) of aerosol number size distributions (particles with diameters (Dp) from 7 nm through 14 μm) was developed using observations from a scanning mobility particle sizer, aerodynamic particle sizer, and a condensation particle counter at the Department of Energy's Southern Great Plains (SGP) site. This dataset was used for two purposes. First, typical characteristics of the aerosol size distribution (number, surface area, and volume) were calculated for the SGP site, both for the entire dataset and on a seasonal basis, and size distribution lognormal fit parameters are provided. While the median size distributions generally had similar shapes (4 lognormal modes) in all the seasons, there were some significant differences between seasons. These differences were most significant in the smallest particles (Dp 800 nm). Second, power spectral analysis was conducted on this long-term dataset to determine key temporal cycles of total aerosol concentrations, as well as aerosol concentrations in specified size ranges. The strongest cyclic signal was associated with a diurnal cycle in total aerosol number concentrations that was driven by the number concentrations of the smallest particles (Dp

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Size-resolved and bulk activation properties of aerosols in the North China Plain

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-3835-2011 ◽

2011 ◽

Vol 11 (8) ◽

pp. 3835-3846 ◽

Cited By ~ 85

Author(s):

Z. Z. Deng ◽

C. S. Zhao ◽

N. Ma ◽

P. F. Liu ◽

L. Ran ◽

...

Keyword(s):

Size Distribution ◽

North China Plain ◽

North China ◽

Cloud Condensation Nuclei ◽

Number Concentration ◽

Anthropogenic Aerosol ◽

Number Size Distribution ◽

The North ◽

The North China Plain ◽

Activation Ratio

Abstract. Size-resolved and bulk activation properties of aerosols were measured at a regional/suburban site in the North China Plain (NCP), which is occasionally heavily polluted by anthropogenic aerosol particles and gases. A Cloud Condensation Nuclei (CCN) closure study is conducted with bulk CCN number concentration (NCCN) and calculated CCN number concentration based on the aerosol number size distribution and size-resolved activation properties. The observed CCN number concentration (NCCN-obs) are higher than those observed in other locations than China, with average NCCN-obs of roughly 2000, 3000, 6000, 10 000 and 13 000 cm−3 at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.70%, respectively. An inferred critical dry diameter (Dm) is calculated based on the NCCN-obs and aerosol number size distribution assuming homogeneous chemical composition. The inferred cut-off diameters are in the ranges of 190–280, 160–260, 95–180, 65–120 and 50–100 nm at supersaturations of 0.056, 0.083, 0.17, 0.35 and 0.7%, with their mean values 230.1, 198.4, 128.4, 86.4 and 69.2 nm, respectively. Size-resolved activation measurements show that most of the 300 nm particles are activated at the investigated supersaturations, while almost no particles of 30 nm are activated even at the highest supersaturation of 0.72%. The activation ratio increases with increasing supersaturation and particle size. The slopes of the activation curves for ambient aerosols are not as steep as those observed in calibrations with ammonium sulfate suggesting that the observed aerosols is an external mixture of more hygroscopic and hydrophobic particles. The calculated CCN number concentrations (NCCN-calc) based on the size-resolved activation ratio and aerosol number size distribution correlate well with the NCCN-obs, and show an average overestimation of 19%. Sensitivity studies of the CCN closure show that the NCCN at each supersaturation is well predicted with the campaign average of size-resolved activation curves. These results indicate that the aerosol number size distribution is critical in the prediction of possible CCN. The CCN number concentration can be reliably estimated using time-averaged, size-resolved activation efficiencies without accounting for the temporal variations.

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Measurement of nonvolatile particle number size distribution

Atmospheric Measurement Techniques ◽

10.5194/amt-9-103-2016 ◽

2016 ◽

Vol 9 (1) ◽

pp. 103-114 ◽

Cited By ~ 14

Author(s):

G. I. Gkatzelis ◽

D. K. Papanastasiou ◽

K. Florou ◽

C. Kaltsonoudis ◽

E. Louvaris ◽

...

Keyword(s):

Size Distribution ◽

Black Carbon ◽

Biomass Burning ◽

Particle Number ◽

Number Concentration ◽

Experimental Methodology ◽

Particle Number Concentration ◽

Scanning Mobility Particle Sizer ◽

Number Size Distribution ◽

Particle Sizer

Abstract. An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50–60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15–20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA is of extremely low volatility.

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Effects of reformed fuel on dual-fuel combustion particulate morphology

International Journal of Engine Research ◽

10.1177/1468087419879782 ◽

2019 ◽

pp. 146808741987978

Author(s):

Flavio Dal Forno Chuahy ◽

Tyler Strickland ◽

Nicholas Ryan Walker ◽

Sage L Kokjohn

Keyword(s):

Particle Size ◽

Fuel Combustion ◽

Dual Fuel ◽

Scanning Mobility Particle Sizer ◽

Reactivity Controlled Compression Ignition ◽

Condensation Particle Counter ◽

Computational Fluid Dynamics Simulations ◽

Dual Fuel Combustion ◽

Particle Sizer ◽

Dynamics Simulations

Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used to replace diesel fuel and enable dual-fuel combustion strategies. The role of port-fuel injected syngas, composed of equal parts hydrogen and carbon monoxide by volume, was investigated experimentally for soot reduction benefits under diesel pilot ignition and reactivity controlled compression ignition strategies. Particle size distribution measurements were made with a scanning mobility particle sizer and condensation particle counter for different levels of syngas substitution. To explain the experimental results, computational fluid dynamics simulations utilizing a detailed stochastic soot model were used to validate and initialize additional simulations that isolate mixing and chemistry effects. Based on these simulations, the influence of adding syngas on soot particle size and quantity is discussed.

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Quantifying aerosol size distributions and their temporal variability in the Southern Great Plains, USA

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11985-2019 ◽

2019 ◽

Vol 19 (18) ◽

pp. 11985-12006 ◽

Cited By ~ 4

Author(s):

Peter J. Marinescu ◽

Ezra J. T. Levin ◽

Don Collins ◽

Sonia M. Kreidenweis ◽

Susan C. van den Heever

Keyword(s):

Size Distribution ◽

Great Plains ◽

Diurnal Cycle ◽

Particle Formation ◽

Aerosol Size Distribution ◽

Size Distributions ◽

New Particle Formation ◽

Scanning Mobility Particle Sizer ◽

Southern Great Plains ◽

Particle Sizer

Abstract. A quality-controlled, 5-year dataset of aerosol number size distributions (particles with diameters (Dp) from 7 nm through 14 µm) was developed using observations from a scanning mobility particle sizer, aerodynamic particle sizer, and a condensation particle counter at the Department of Energy's Southern Great Plains (SGP) site. This dataset was used for two purposes. First, typical characteristics of the aerosol size distribution (number, surface area, and volume) were calculated for the SGP site, both for the entire dataset and on a seasonal basis, and size distribution lognormal fit parameters are provided. While the median size distributions generally had similar shapes (four lognormal modes) in all the seasons, there were some significant differences between seasons. These differences were most significant in the smallest particles (Dp<30 nm) and largest particles (Dp>800 nm). Second, power spectral analysis was conducted on this long-term dataset to determine key temporal cycles of total aerosol concentrations, as well as aerosol concentrations in specified size ranges. The strongest cyclic signal was associated with a diurnal cycle in total aerosol number concentrations that was driven by the number concentrations of the smallest particles (Dp<30 nm). This diurnal cycle in the smallest particles occurred in all seasons in ∼50 % of the observations, suggesting a persistent influence of new particle formation events on the number concentrations observed at the SGP site. This finding is in contrast with earlier studies that suggest new particle formation is observed primarily in the springtime at this site. The timing of peak concentrations associated with this diurnal cycle was shifted by several hours depending on the season, which was consistent with seasonal differences in insolation and boundary layer processes. Significant diurnal cycles in number concentrations were also found for particles with Dp between 140 and 800 nm, with peak concentrations occurring in the overnight hours, which were primarily associated with both nitrate and organic aerosol cycles. Weaker cyclic signals were observed for longer timescales (days to weeks) and are hypothesized to be related to the timescales of synoptic weather variability. The strongest periodic signals (3.5–5 and 7 d cycles) for these longer timescales varied depending on the season, with no cyclic signals and the lowest variability in the summer.

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