Transient coupled conduction and radiation heat transfer in a two-layer scattering media with diffuse reflective boundary

Transient coupled radiation and conduction in a two-layer isotropic scattering semitransparent non-gray medium with thin opaque coatings was studied by ray tracing/nodal analysis method. Both boundary surfaces were opaque and diffuse, and the interface between the two layers was semitransparent. The two layers had different thermophysical characteristics and the refractive indices were greater than 1. The radiative transfer coefficients of the composite were deduced for diffuse reflection, with multiple reflections at the surface and multiple scattering in the media. The radiative heat source term was calculated from the radiative transfer factors. The transient energy equation was solved by the control-volume method. The steady-state and transient temperature distributions and heat flux densities in the composite were obtained for the general boundary conditions of external radiation and convection. A comparison of the present results with previous results obtained with the Galerkin method shows that the equations are correct and the results are more accurate.