Transient coupled radiation and conduction in an absorbing and scattering composite layer

A method is developed for obtaining transient temperatures and heat flux de nsities in a two-layer isotropic scattering semitransparent composite with spectrally dependent radiative properties. The radiative transfer coefficie nts of the absorbing and isotropic scattering composite are deduced by the ray tracing method in combination with Hottel and Sarofim's zonal method (H ottel, H. C., and Sarofim, A. F., Radiative Transfer, McGraw-Hill, New York , 1967, pp. 265, 266). The boundary surfaces and the internal interface are semitransparent, and the reflections are assumed to be diffuse or specular . The radiative heat source term is calculated by the radiative transfer co efficients. The transient energy equation is solved by the full implicit co ntrol-volume method in combination with the spectral band model. An advanta ge of the method is that it needs only to disperse the space position, but not to disperse the solid angle. A comparison of the results, obtained unde r diffuse reflection, with previous results shows that the equations are co rrect, and the results are more accurate. The analysis includes the influen ces of the scattering albedo, the dimensionless thickness, the conduction-r adiation parameter, the convection-radiation parameter, the spectral proper ties, and the reflective mode on the transient temperature field and the he at flux density.