ON RADIATIVE HEAT TRANSFER IN SOLIDS.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF FUEL SCIENCE
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Analysis of radiative heat transfer inside a solid in which there is simultaneous transmission, absorbtion, and re-radiation and conduction is neglected leads to two simultaneous integral equations whose solution leads to a temperature T-distance x profile at steady state of the form T to the 4th power T T sub zero to the 4th power - kB2 sigmax where k is the specific absorbtion for the material, B the net radiative heat transfer, sigma is Boltzmans constant. Values of k assumed independent of temperature and wavelength for which radiative heat transfer is estimated to be a significant contribution range from 0.1 to 100 clear, transparent glasses to opaque grey solids. In combustion and ablation situations calculation of the time constants for establishment of radiative and conductive steady-state show that radiation might even be the dominant mode of heat transfer. Another result that emerges from the analysis is an equation for the overall solid emissivity which is found to vary with the temperature profile inside the solid. Author