Transient and Steady-State Combined Heat Transfer in Semi-Transparent Materials Subjected to a Pulse or a Step Irradiation

A numerical analysis based on the finite difference scheme and Hottel’s zonal method generalized by the ray tracing method is carried out to treat the one-dimensional transient and steady-state combined radiative-conductive heat transfer in non-gray Semi-Transparent Materials (STM), especially glasses, subjected to an external pulse or a step of irradiation. Coupling problems are studied for two optical boundary conditions: opaque and vitreous interfaces with specular reflections. The influence of slab thickness, spectral properties of the STM, wavelength of the incident radiation, and diffusivity coefficient are examined. It is pointed out that the application of the laser flash method in thermal metrology may give irrelevant results if the basic heat transfer model is not able to take into account radiative-conductive coupling phenomena. The effect of semi-transparency on the steady-state temperature distribution is also examined for materials ranging from fully opaque to fully transparent.