44 O 03 Gas-phase particle size distributions of (Bi,Pb)-Sr-Ca-Cu-O superconducting powders made via spray pyrolysis

1993 ◽  
Vol 24 ◽  
pp. S571-S572
Author(s):  
J. Joutsensaari ◽  
E.I. Kauppinen ◽  
J.K. Jokiniemi ◽  
A.S. Gurav ◽  
T.T. Kodas
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Gas Phase ◽  
Phase Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Gas-phase particle size distributions and lead loss during spray pyrolysis of (Bi,Pb)–Sr–Ca–Cu–O

1995 ◽  
Vol 10 (7) ◽  
pp. 1644-1652 ◽  
Author(s):  
Abhijit S. Gurav ◽  
Toivo T. Kodas ◽  
Jorma Joutsensaari ◽  
Esko I. Kauppincn ◽  
Riitta Zilliacus
Keyword(s):  
Particle Size ◽  
Spray Pyrolysis ◽  
Gas Phase ◽  
Phase Particle ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Processing Temperature ◽  
Average Particle ◽  
Size Distributions ◽  
Particle Size Distributions

Gas-phase particle size distributions and lead loss were measured during formation of (Bi,Pb)-Sr-Ca-Cu-O and pure PbO particles by spray pyrolysis at different temperatures. A differential mobility analyzer (DMA) in conjunction with a condensation particle counter (CPC) was used to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. For (Bi,Pb)-Sr-Ca-Cu-O, as the processing temperature was raised from 200 to 700 °C, the number average particle size decreased due to metal nitrate decomposition, intraparticle reactions forming mixed-metal oxides and particle densification. The geometric number mean particle diameter was 0.12 μm at 200 °C and reduced to 0.08 and 0.07 μm, respectively, at 700 and 900 °C. When the reactor temperature was raised from 700 and 800 °C to 900 °C, a large number (∼107 no./cm3) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls. Particles made at temperatures up to 700 °C maintained their initial stoichiometry over the whole range of particle sizes monitorcd; however, those made at 800 °C and above were heavily depleted in lead in the size range 0.5–5.0 μm. The evaporative losses of lead oxide from (Bi,Pb)-Sr-Ca-Cu-O particles were compared with the losses from PbO particles to gain insight into the pathways involved in lead loss and the role of intraparticle processes in controlling it.

Gas-phase particle size distributions during vapor condensation of fullerenes

1994 ◽  
Vol 4 (5) ◽  
pp. 491-496 ◽  
Author(s):  
A.S. Gurav ◽  
T.T. Kodas ◽  
L.M. Wang ◽  
E.I. Kauppinen ◽  
J. Joutsensaari
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Phase Particle ◽  
Vapor Condensation ◽  
Size Distributions ◽  
Particle Size Distributions

Road tunnel measurements of submicrometer particle size distributions, elemental composition and gas phase components

1999 ◽  
Vol 30 ◽  
pp. S49-S50 ◽  
Author(s):  
E. Swietlicki ◽  
J. Zhou ◽  
C. Johansson ◽  
R. Westerholm ◽  
G. Papaspiropoulos
Keyword(s):  
Particle Size ◽  
Elemental Composition ◽  
Gas Phase ◽  
Size Distributions ◽  
Road Tunnel ◽  
Particle Size Distributions

scholarly journals Improved Parameterization of Ice Particle Size Distributions Using Uncorrelated Mass Spectrum Parameters: Results from GCPEx

2019 ◽  
Vol 58 (8) ◽  
pp. 1657-1676 ◽  
Author(s):  
Paloma Borque ◽  
Kirstin J. Harnos ◽  
Stephen W. Nesbitt ◽  
Greg M. McFarquhar
Keyword(s):  
Particle Size ◽  
Phase Particle ◽  
Cold Season ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Microphysical Properties ◽  
Retrieval Algorithms ◽  
Mass Dimension ◽  
Selection Of ◽  
Ice Phase

AbstractSatellite retrieval algorithms and model microphysical parameterizations require guidance from observations to improve the representation of ice-phase microphysical quantities and processes. Here, a parameterization for ice-phase particle size distributions (PSDs) is developed using in situ measurements of cloud microphysical properties collected during the Global Precipitation Measurement (GPM) Cold-Season Precipitation Experiment (GCPEx). This parameterization takes advantage of the relation between the gamma-shape parameter μ and the mass-weighted mean diameter Dm of the ice-phase PSD sampled during GCPEx. The retrieval of effective reflectivity Ze and ice water content (IWC) from the reconstructed PSD using the μ–Dm relationship was tested with independent measurements of Ze and IWC and overall leads to a mean error of 8% in both variables. This represents an improvement when compared with errors using the Field et al. parameterization of 10% in IWC and 37% in Ze. Current radar precipitation retrieval algorithms from GPM assume that the PSD follows a gamma distribution with μ = 3. This assumption leads to a mean overestimation of 5% in the retrieved Ze, whereas applying the μ–Dm relationship found here reduces this bias to an overestimation of less than 1%. Proper selection of the a and b coefficients in the mass–dimension relationship is also of crucial importance for retrievals. An inappropriate selection of a and b, even from values observed in previous studies in similar environments and cloud types, can lead to more than 100% bias in IWC and Ze for the ice-phase particles analyzed here.

scholarly journals Modelling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

2015 ◽  
Vol 15 (23) ◽  
pp. 35157-35200
Author(s):  
M. Karl ◽  
J. Kukkonen ◽  
M. P. Keuken ◽  
S. Lützenkirchen ◽  
L. Pirjola ◽  
...  
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Dry Deposition ◽  
Particle Number ◽  
Measured Data ◽  
Sensitivity Analyses ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Coagulation Of Particles ◽  
Neighborhood Scale

Abstract. This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of one hour, i.e. on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using an aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of n-alkanes, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. It was not necessary to model the nucleation of gas-phase vapors, as the computations were started with roadside conditions. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, condensational growth contributed significantly to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes can predict particle number concentrations between roadside and the urban background with an inaccuracy of ∼ 10 %, compared to the fully size-resolved MAFOR model.

scholarly journals Modeling and measurements of urban aerosol processes on the neighborhood scale in Rotterdam, Oslo and Helsinki

2016 ◽  
Vol 16 (8) ◽  
pp. 4817-4835 ◽  
Author(s):  
Matthias Karl ◽  
Jaakko Kukkonen ◽  
Menno P. Keuken ◽  
Susanne Lützenkirchen ◽  
Liisa Pirjola ◽  
...  
Keyword(s):  
Particle Size ◽  
Gas Phase ◽  
Dry Deposition ◽  
Particle Number ◽  
Measured Data ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Organic Vapors ◽  
Coagulation Of Particles ◽  
Neighborhood Scale

Abstract. This study evaluates the influence of aerosol processes on the particle number (PN) concentrations in three major European cities on the temporal scale of 1 h, i.e., on the neighborhood and city scales. We have used selected measured data of particle size distributions from previous campaigns in the cities of Helsinki, Oslo and Rotterdam. The aerosol transformation processes were evaluated using the aerosol dynamics model MAFOR, combined with a simplified treatment of roadside and urban atmospheric dispersion. We have compared the model predictions of particle number size distributions with the measured data, and conducted sensitivity analyses regarding the influence of various model input variables. We also present a simplified parameterization for aerosol processes, which is based on the more complex aerosol process computations; this simple model can easily be implemented to both Gaussian and Eulerian urban dispersion models. Aerosol processes considered in this study were (i) the coagulation of particles, (ii) the condensation and evaporation of two organic vapors, and (iii) dry deposition. The chemical transformation of gas-phase compounds was not taken into account. By choosing concentrations and particle size distributions at roadside as starting point of the computations, nucleation of gas-phase vapors from the exhaust has been regarded as post tail-pipe emission, avoiding the need to include nucleation in the process analysis. Dry deposition and coagulation of particles were identified to be the most important aerosol dynamic processes that control the evolution and removal of particles. The error of the contribution from dry deposition to PN losses due to the uncertainty of measured deposition velocities ranges from −76 to +64 %. The removal of nanoparticles by coagulation enhanced considerably when considering the fractal nature of soot aggregates and the combined effect of van der Waals and viscous interactions. The effect of condensation and evaporation of organic vapors emitted by vehicles on particle numbers and on particle size distributions was examined. Under inefficient dispersion conditions, the model predicts that condensational growth contributes to the evolution of PN from roadside to the neighborhood scale. The simplified parameterization of aerosol processes predicts the change in particle number concentrations between roadside and urban background within 10 % of that predicted by the fully size-resolved MAFOR model.

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