期刊
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
卷 51, 期 3-4, 页码 929-940出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijheatmasstransfer.2007.10.010
关键词
thermal radiation; metal foam; modeling; conductivity; emission; reflectance; extinction; measurement
An analytical model is developed to characterize the radiative transport process in highly porous, open-celled metal foams having idealized cellular morphologies in terms of fundamental radiative parameters such as emissivity, reflectivity and configuration factors. In comparison with the conventional two-flux approach or the diffusion approximation utilizing the Rosseland mean coefficient, the present model is explicit and yet relatively simple. Overall, the predicted effective radiative conductivity as a function of pore size and relative density (defined as the ratio of foam density to solid density) agrees well with that measured using a guarded-hot-plate apparatus for steel alloy foams. A systematic parametric study is subsequently carried out. The contribution of reflectance to thermal radiation is found to be significant, up to 50%, but the effect of temperature gradient is relatively small. The equivalent radiative conductivity increases linearly with increasing cell size for a fixed relative density, whilst for a given cell size the variation of relative density only has a small effect on radiation due to the mixed effects of increased emission and extinction. (C) 2007 Elsevier Ltd. All rights reserved.
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