Shrinking core like fluid solid reactions—A dispersion model accounting for fluid phase volume change and solid phase particle size distributions

2012 ◽  
Vol 69 (1) ◽  
pp. 492-502 ◽  
Author(s):  
Tilman Knorr ◽  
Markus Kaiser ◽  
Friedrich Glenk ◽  
Bastian J.M. Etzold
Keyword(s):  
Particle Size ◽  
Solid Phase ◽  
Dispersion Model ◽  
Phase Particle ◽  
Fluid Phase ◽  
Size Distributions ◽  
Phase Volume ◽  
Particle Size Distributions ◽  
Solid Phase Particle ◽  
Shrinking Core

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.

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

Investigation of Correlations between Shear History and Microstructure of Semi-Solid Alloys

2012 ◽  
Vol 192-193 ◽  
pp. 251-256 ◽  
Author(s):  
Michael Modigell ◽  
Annalisa Pola ◽  
Michel Suéry ◽  
Christoph Zang
Keyword(s):  
Particle Size ◽  
Shear Rate ◽  
Solid Phase ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Microstructure Parameters ◽  
Semi Solid ◽  
Solid Alloys ◽  
Section Analysis

Rheological properties of semi-solid alloys are closely knit to the solid-phase microstructure. Parameters such as particle size distribution are commonly determined by 2D cross section analysis. The determination of mechanisms such as particle deagglomeration with increasing shear rate however, requires information on the 3D spatial distribution. By means of synchrotron radiation tomography and SEM on AlCu samples, particle size distributions and the not yet microscopically observed interrelation of shear rate and particle agglomeration in thixo-material is investigated.

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.

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

Comparison of cirrus clouds in naturally and anthropogenically influenced regions of the atmosphere

2020 ◽  
Author(s):  
Maximilian Dollner ◽  
Josef Gasteiger ◽  
Charles A. Brock ◽  
Manuel Schöberl ◽  
Christina Williamson ◽  
...  
Keyword(s):  
Particle Size ◽  
Field Experiments ◽  
Anthropogenic Impacts ◽  
Dispersion Model ◽  
Cirrus Clouds ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Cloud Particle ◽  
Microphysical Properties ◽  
Aerosol Particle Size

<p>Cirrus clouds are an important contributor to the uncertainty of future climate prediction, especially due to the weak understanding of anthropogenic impacts on cirrus clouds.</p><p>We investigate aerosol and cloud microphysical properties of the remote atmosphere over the Pacific and Atlantic Oceans from about 80°N to 86°S and the region in the Mediterranean using airborne aerosol and cloud measurements of the entire atmospheric column up to approx. 13 km from the ATom (Atmospheric Tomography; 2016-2018) and the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics; 2017) field experiments, respectively. Aerosol microphysical properties are retrieved from in-situ measurements of aerosol particle size distributions between 0.003 and 50 µm, single particle mass spectrometry as well as simulations with the Lagrangian transport and dispersion model FLEXPART. The microphysical properties of cirrus clouds are obtained from size distribution measurements covering the range between 3 and 930 µm.</p><p>In this study we show microphysical properties of aerosols and cirrus clouds in regions with high mineral dust concentrations as well as pristine and anthropogenic influenced regions in order to advance the knowledge of the natural and anthropogenic impact on cirrus clouds.  We present comparisons of ice crystal number concentrations, aerosol and cloud particle size distributions, and meteorological conditions of cirrus clouds in the above-mentioned regions of the atmosphere.</p>

254. A Comparison of the Particle Size Distributions for Aerosols Generated During Wet Grinding and Dry Deburring of Beryllium

1999 ◽  
Author(s):  
K.K. Ellis ◽  
R. Buchan ◽  
M. Hoover ◽  
J. Martyny ◽  
B. Bucher-Bartleson ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Wet Grinding
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