Albedos and asymmetry factors of the phase functions for packed-sphere systems

Kamiuto, Kouichi; Iwamoto, Mitsuo; Nishimura, T.; Satô, Masayoshi

doi:10.1016/0022-4073(91)90095-8

Cited by 20 publications

(3 citation statements)

References 11 publications

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“…D'autres travaux traitant de la diffusion dépendante dans les milieux constitués de particules sphériques sont disponibles dans la littérature. On citera par exemple les travaux de : Kam90b] et Kamiuto et al[KISN91,KINS91] qui là encore se focalisent sur de grandes sphères devant la longueur d'onde ; -Kamiuto et Yee[KY05] qui considèrent des sphères opaques. On remarque que chaque modèle ou corrélation cité jusqu'à présent ne s'applique qu'à un domaine limité de paramètres de taille et que malheureusement ces domaines ne sont pas ceux auxquels nous sommes confrontés avec nos matériaux.…”

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Experimental Determination and Modeling of the Radiative Properties of Silica Nanoporous Matrices

Lallich

Enguehard

Baillis

2009

Journal of Heat Transfer

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Superinsulating materials are currently of interest because the heating and cooling of houses and offices are responsible for an important part of CO 2 emissions. In this study, we aim at modeling the radiative transfer in nanoporous silica matrices that are the principal components of nanoporous superinsulating materials. We first elaborate samples from different pyrogenic amorphous silica powders that slightly differ one from another in terms of specific surface, nanoparticle diameter, and composition. The various samples are optically characterized using two spectrometers operating on the wavelength range (250 nm; 20 m). Once the hemispherical transmittance and reflectance spectra are measured, we deduce the radiative properties using a parameter identification technique. Then, as the considered media are made of packed quasispherical nanoparticles, we try to model their radiative properties using the original Mie theory. To obtain a good agreement between experiment and theory on a large part of the wavelength range, we have to consider scatterers that are up to five times larger than the primary nanoparticles; this is attributed to the fact that the scatterers are not the nanoparticles but aggregates of nanoparticles that are constituted during the fabrication process of the powders. Nevertheless, in the small wavelength range ( smaller than 1 m), we can never get a satisfactory agreement using the Mie theory. This disagreement is attributed to the fact that the original Mie theory does not take into account the nanostructure of the aggregates. So we have developed a code based on the discrete dipole approximation that improves the modeling results in the small wavelength range, basing our computations on aggregates generated using the diffusion-limited cluster-cluster aggregation algorithm in order to ensure a fractal dimension close to what is usually found with aggregates of silica nanoparticles.

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Experimental Determination and Modeling of the Radiative Properties of Silica Nanoporous Matrices

Lallich

Enguehard

Baillis

2009

Journal of Heat Transfer

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“…The modeling of radiative properties of beds of spherical particles has received much attention. Among other methods, correlations have been used by Kamiuto [104] and Kamiuto et al [105], and scaling factors by Kaviany and Singh [106], and Singh and Kaviany [107], to approximate dependent scattering effects. Dombrovsky derived approximate models for the radiation properties of packed hollow microspheres.…”

Section: Densely Packed Spherical Particle Bedsmentioning

confidence: 99%

Thermal Radiative Properties of Complex Media: Theoretical Prediction Versus Experimental Identification

Sacadura

2011

Heat Transfer Engineering

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In many engineering applications and natural phenomena, thermal radiation interacts with complex media composed of dispersed phases that may be of different type: solid/solid, solid/gas, or liquid/gas. Most of them are semitransparent media that emit, absorb, and scatter thermal radiation. Heat transfer by combined radiation with conduction or convection in such media is a problem of high practical importance, mostly in situations where radiation is a dominant mode. Improvement of thermal performance of such materials or of the manufacturing processes that involve these media requires the availability of efficient methods (i) for radiative transfer modeling, and (ii) to predict and to experimentally determine the thermophysical properties intended to feed the models. This paper is focused on radiative properties assessment. After a brief overview of the materials and properties of interest, the emphasis is put on methodology of property investigation combining both theoretical prediction and experimental identification. Examples related to different particulate media are presented, showing recent advances and needs for further investigation.

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“…The total heat flux qt across a packed bed with a height Yo can be evaluated from (17) where T 8 and T~. denote the hot and cold boundary temperatures of a packed bed, respectively and keff the mean total effective thermal conductivity defined by (18) keff is often replaced with kef!…”

Section: Total Effective Thermal Conductivity Of Packed Bedmentioning

confidence: 99%

Analytical Expression for Total Effective Thermal Conductivities of Packed Beds

Kamiuto

1991

Journal of Nuclear Science and Technology

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Albedos and asymmetry factors of the phase functions for packed-sphere systems

Cited by 20 publications

References 11 publications

Experimental Determination and Modeling of the Radiative Properties of Silica Nanoporous Matrices

Experimental Determination and Modeling of the Radiative Properties of Silica Nanoporous Matrices

Thermal Radiative Properties of Complex Media: Theoretical Prediction Versus Experimental Identification

Analytical Expression for Total Effective Thermal Conductivities of Packed Beds

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