Radiative Characteristics of Beds of Spheres Containing an Absorbing and Scattering Medium

The aim of this paper is to characterize the radiative behavior of beds made of spherical particles containing an homogeneous absorbing and scattering medium whose radiative properties (extinction coefficient, scattering albedo, and scattering phase function) are known. In the beds studied, the spherical particles could be far apart, close to each other, or even compressed. When the particles are sufficiently distant from each other to scatter independently, the radiative properties of the whole bed are determined from the radiative characteristics of one particle alone. These characteristics are determined using a Monte Carlo procedure applied to one bead alone. On the other hand, when particles get closer to each other independent scattering theory is no longer valid, and dependent scattering effects have to be taken into account. We then apply a Monte Carlo procedure to the whole bed and identify the extinction coefficient, scattering albedo, and scattering phase function of the equivalent homogeneous absorbing and scattering medium that best matches the radiative behavior of the bed. The simulation permits us to characterize the evolution of the radiative properties of the bed with the inside medium properties and the characteristics of the bed. Moreover, we investigate the limit of validity of the independent scattering hypothesis.

[1]  C. L. Tien,et al.  Radiative Transfer in Packed Spheres , 1974 .

[2]  M. Brewster.  RADIATIVE HEAT TRANSFER IN FLUIDIZED-BED COMBUSTORS. , 1983 .

[3]  Dominique Baillis,et al.  Thermal radiation properties of dispersed media: theoretical prediction and experimental characterization , 2000 .

[4]  Massoud Kaviany,et al.  Independent theory versus direct simulation of radiation heat transfer in packed beds , 1991 .

[5]  Dominique Baillis,et al.  Radiative Characteristics of Opaque Spherical Particles Beds: A New Method of Prediction , 2004 .

[6]  H. Hottel,et al.  Optical Properties of Coatings. Effect of Pigment Concentration , 1971 .

[7]  J. R. Howell,et al.  RADIATIVE HEAT TRANSFER THROUGH A RANDOMLY PACKED BED OF SPHERES BY THE MONTE CARLO METHOD. , 1982 .

[8]  K. Kamiuto,et al.  Correlated radiative transfer in packed-sphere systems , 1990 .

[9]  Dominique Baillis,et al.  Spectral Radiative Properties of Open-Cell Foam Insulation , 1999 .

[10]  L. Dombrovsky.  A modified differential approximation for thermal radiation of semitransparent nonisothermal particles: application to optical diagnostics of plasma spraying , 2002 .

[11]  Andrei G. Fedorov,et al.  Radiation Characteristics of Glass Foams , 2004 .

[12]  M. Pinar Mengüç,et al.  Depolarization of radiation by non-absorbing foams , 2002 .

[13]  M. Pinar Mengüç,et al.  Radiative Transfer in Dispersed Media , 1989 .

[14]  Massoud Kaviany,et al.  Modelling radiative heat transfer in packed beds , 1992 .

[15]  Radiative heat transfer in fluidized beds , 1993 .