scholarly journals Tomography-Based Analysis of Radiative Transfer in Reacting Packed Beds Undergoing a Solid-Gas Thermochemical Transformation

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Sophia Haussener ◽  
Wojciech Lipiński ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Effective Properties ◽  
Packed Bed ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Thermochemical Transformation ◽  
Reaction Extent ◽  
Fluid Boundary ◽  
Point Correlation ◽  
Scattering Phase ◽  
Scattering Phase Function

A reacting packed-bed undergoing a high-temperature thermochemical solid-gas transformation is considered. The steam- and dry-gasification of carbonaceous materials to syngas is selected as the model reaction. The exact 3D digital geometrical representation of the packed-bed is obtained by computer tomography and used in direct pore-level simulations to characterize its morphological and radiative transport properties as a function of the reaction extent. Two-point correlation functions and mathematical morphology operations are applied to calculate porosities, specific surfaces, particle-size distributions, and representative elementary volumes. The collision-based Monte Carlo method is applied to determine the probability distribution of attenuation path length and direction of incidence at the solid-fluid boundary, which are linked to the extinction coefficient, scattering phase function, and scattering albedo. These effective properties can be then incorporated in continuum models of the reacting packed-bed.

scholarly journals Tomography-Based Analysis of Radiative Transfer in Reacting Packed Beds Undergoing a Solid-Gas Thermochemical Transformation

2009 ◽  
Author(s):  
Sophia Haussener ◽  
Wojciech Lipin´ski ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Effective Properties ◽  
Packed Bed ◽  
Steam Gasification ◽  
Domain Modeling ◽  
Thermochemical Transformation ◽  
Reaction Extent ◽  
Fluid Boundary ◽  
Point Correlation ◽  
Scattering Phase ◽  
Scattering Phase Function

A reacting packed bed undergoing a high-temperature thermochemical solid-gas transformation is considered. The steam-gasification of carbonaceous materials into syngas is selected as the model reaction. The exact 3D geometrical configuration of the packed bed is obtained by computer tomography, digitalized, and used in direct pore-level simulations to characterize its morphological and radiative transport properties as a function of the reaction extent. Two-point correlation functions and mathematical morphology operations are applied to calculate porosities, specific surfaces, particle size distributions, and representative elementary volumes. The collision-based Monte Carlo method is applied to determine the probability distribution of attenuation path length and direction of incidence at the solid-fluid boundary, which are linked to the extinction coefficient, scattering phase function, and albedo. These effective properties can then be incorporated in continuum domain modeling of the packed bed.

scholarly journals First correlated measurements of the shape and scattering properties of cloud particles using the new Particle Habit Imaging and Polar Scattering (PHIPS) probe

2011 ◽  
Vol 4 (3) ◽  
pp. 2883-2930
Author(s):  
A. Abdelmonem ◽  
M. Schnaiter ◽  
P. Amsler ◽  
E. Hesse ◽  
J. Meyer ◽  
...  
Keyword(s):  
Optical Sensor ◽  
Optical Resolution ◽  
Single Scattering ◽  
Cirrus Clouds ◽  
Size Distributions ◽  
Radiative Impact ◽  
Scattering Phase ◽  
Cloud Particles ◽  
Ice Crystal Size ◽  
Scattering Phase Function

Abstract. Studying the radiative impact of cirrus clouds requires the knowledge of the link between their microphysics and the single scattering properties of the cloud particles. Usually, this link is created by modeling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. We present here a novel optical sensor (the Particle Habit Imaging and Polar Scattering probe, PHIPS) designed to measure the 3-D morphology and the corresponding optical and microphysical parameters of individual cloud particles, simultaneously. Clouds containing particles ranging in size from a few micrometers to about 800 μm diameter can be systematically characterized with an optical resolution power of 2 μm and polar scattering resolution of 1° for forward scattering directions (from 1° to 10°) and 8° for side and backscattering directions (from 18° to 170°). The maximum acquisition rates for scattering phase functions and images are 262 KHz and 10 Hz, respectively. Some preliminary results collected in two ice cloud campaigns which were conducted in the AIDA cloud simulation chamber are presented. PHIPS showed reliability in operation and produced comparable size distributions and images to those given by other certified cloud particles instruments. A 3-D model of a hexagonal ice plate is constructed and the corresponding scattering phase function is compared to that modeled using the Ray Tracing with Diffraction on Facets (RTDF) program. PHIPS is candidate to be a novel air borne optical sensor for studying the radiative impact of cirrus clouds and correlating the particle habit-scattering properties which will serve as a reference for other single, or multi-independent, measurements instruments.

Particle sizes in planetary rings from forward-scattering and spectral-extinction observations

1984 ◽  
Vol 75 ◽  
pp. 281
Author(s):  
E.A. Marouf ◽  
G.L. Tyler ◽  
V.R. Eshleman
Keyword(s):  
Forward Scattering ◽  
Size Distributions ◽  
Planetary Rings ◽  
Direct Signal ◽  
Spectral Signatures ◽  
Size Information ◽  
Scattering Geometry ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Weighted Measure

The forward scattering geometry is favored for observing the size distributions of particles in planetary rings. One reason is the dominance of the collective diffraction lobe of the particles in the near-forward scattering. For tenuous rings, like the Jovian ring, Saturn's ring C, ring F, and Cassini division, observation of the shape of this lobe as a function of scattering angles decouples the size information from the exact particle shape, surface structure, and material. For more opaque rings, such as Saturn's ring A and possibly some of the Uranian rings, the shape of the forward lobe can be contaminated by multiple scattering which must be deconvolved before size information can be recovered. Knowledge of the opacity of the rings is required to carry out the deconvolution.with the degree of success largely dependent on the apparent ring opening. Here, the forward geometry provides a convenient means for determining the “true” opacity by measurements of the extinction of the direct ray between the spacecraft source and receiver. At the present time, only the radio occultation technique has the capability of separating this direct signal component from the forward-scattered signal. This separation is based on the distinct spectral signatures of the direct and scattered components, and permits simultaneous and independent estimates of the opacity and of the strength and shape of the forward-scattering phase function. Because opacity is an area-weighted measure of the particle distribution , while the diffraction lobe is an area-squared weighted measure of the distribution these two observables complement each other by binding the size distribution over different size ranges.

scholarly journals Tomography-Based Determination of Effective Transport Properties for Reacting Porous Media

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Sophia Haussener ◽  
Iwan Jerjen ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Porous Media ◽  
Transport Properties ◽  
Strong Dependence ◽  
Convective Heat Transfer Coefficient ◽  
Packed Bed ◽  
Morphological Properties ◽  
High Resolution Computed Tomography ◽  
Thermochemical Transformation ◽  
Effective Transport ◽  
Reaction Extent

The effective heat and mass transport properties of a porous packed bed of particles undergoing a high-temperature solid–gas thermochemical transformation are determined. The exact 3D geometry of the reacting porous media is obtained by high-resolution computed tomography. Finite volume techniques are applied to solve the governing conservation equations at the pore-level scale and to determine the effective transport properties as a function of the reaction extent, namely, the convective heat transfer coefficient, permeability, Dupuit–Forchheimer coefficient, tortuosity, and residence time distributions. These exhibit strong dependence on the bed morphological properties (e.g., porosity, specific surface area, particle size) and, consequently, vary with time as the reaction progresses.

scholarly journals Tomography-Based Determination of Effective Transport Properties for Reacting Porous Media

2010 ◽  
Author(s):  
Sophia Haussener ◽  
Iwan Jerjen ◽  
Peter Wyss ◽  
Aldo Steinfeld
Keyword(s):  
Porous Media ◽  
Transport Properties ◽  
Strong Dependence ◽  
Convective Heat Transfer Coefficient ◽  
Packed Bed ◽  
Morphological Properties ◽  
Thermochemical Transformation ◽  
Effective Transport ◽  
Reaction Extent ◽  
Level Scale

The effective heat and mass transport properties of a porous packed bed of particles undergoing a high-temperature solid-gas thermochemical transformation are determined. The exact 3D geometry of the reacting porous media is obtained by high-resolution computer tomography. Finite volume techniques are applied to solve the governing conservation equations at the pore-level scale and to determine the effective transport properties as a function of the reaction extent, namely: the convective heat transfer coefficient, permeability, Dupuit-Forchheimer coefficient, tortuosity and residence time distributions. These exhibit strong dependence on the bed morphological properties (e.g. porosity, specific surface area, particle size) and, consequently, vary with time as the reaction progresses.

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

Measurements of Mineral Particle Size Distributions by a Buoyancy Weighing Method

2010 ◽  
Vol 126 (10/11) ◽  
pp. 577-582 ◽  
Author(s):  
Katsuhiko FURUKAWA ◽  
Yuichi OHIRA ◽  
Eiji OBATA ◽  
Yutaka YOSHIDA
Keyword(s):  
Particle Size ◽  
Mineral Particle ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Weighing Method
Sign in / Sign up

Export Citation Format

Share Document