HIGH HEAT FLUX IN GLASS

摘要

Transient conduction and nongray radiation in an absorbing, emitting and isotropically scattering glass slab with reflective boundaries is solved by the application of an implicit finite difference/discrete ordinates method. Solutions are presented for predicting temperatures and heat fluxes in a one dimensional slab geometry being externally heated by a constant high heat flux at one boundary. The boundaries are assumed to be optically smooth with Fresnel reflection and have a uniform relative real refractive index. The window material is intensely heated to levels that exceed the softening/melting point temperature in order to categorized the transient onset of these conditions without phase or volume change. The numerical results reveal the effects of the system parameters on the heat transfer characteristics. Comparisons are made between a gray model and a 16 band, evenly spaced, nongray model in the 1 to 4μm wavelength region. Precise knowledge of the thermal behavior of the windows is essential to the development of glass and ceramic materials in diathermal and optical applications.