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Thermal radiation greatly affects the transient thermal response of translucent materials in many practical applications, such as radiative heat shields and ignition and flame spreads for translucent plastics. However, because of the complexities that transients impose, less work has been done on the transient analysis of combined radiation–conduction heat transfer than on steady-state analysis. In this study, the transient heat transfer analysis of a polycarbonate (PC) layer was done with the use of the two-flux method and implicit finite difference formulations. The radiative and conductive properties of PC available in the literature, together with computer implementation prepared on the basis of the two-flux method and implicit finite difference formulations, were used to obtain the transient thermal response of a PC layer. On the basis of these results, we show that, compared to the conduction-alone case, the PC layer responded faster when radiation effects were considered. It is also shown that the internal reflectivity of boundaries had a great effect on the thermal response of the layer, whereas the thermal conductivity had a minor influence. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A model is presented for the calculation of transient combined radiative and conductive heat transfer in a semitransparent layer of advanced fiber polymer. This model is based on optical material properties. Different boundary conditions were examined. Each side of the layer was exposed to hot or cold radiative surroundings, whereas each boundary was heated or cooled by convection. Emission within the layer and internal reflections depended on the layer refractive index. The reflected energy and heat conduction distributed energy across the layer and partially equalized the transient temperature distributions. The numerical method is an implicit finite difference procedure with nonuniform space and time increments that has been expanded to include external convection and incident radiation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:4181–4189, 2006

Transient radiative and conductive heat transfer in a translucent medium with isotropic optical properties is investigated. The radiative two-flux equation is coupled with the transient energy equation and both equations are solved simultaneously. Transient solutions are obtained for a plane layer with refractive index equal to or larger than one, and with external convection and radiation at each boundary. Illustrative results obtained with the two-flux method show the effects of changing parameters such as optical thicknesses, refractive index, conduction–radiation parameter, and scattering on the transient temperature distribution within the layer. Results are given at different instances during the transient, and the distribution for the largest time is at or very close to steady state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2277–2283, 2006