THERMAL RADIATIVE PROPERTIES OF GLASS FROM 0.32 TO 206 MUM

The thermal radiative properties of glass are calculated using the optical constants data that are recently published in the literature. The directional-spectral reflectivity, absorptivity and transmissivity of glass are computed from 0.32 to 206 μm. These properties are also integrated to obtain the directional-total and hemispherical-total properties. The systems under investigation include a glass surface, a bulk glass plate and multilayer glass systems. Prediction equations are given to show that in the far IR various property equations can be reduced to a function of surface reflectivity. According to the calculated results, only under the normal incidence condition inside the far IR, the glass has a total reflectivity of 0.107 which is very close to the present design value (0.1). However, if the incident energy is coming from all directions as what is normally encountered in practice, the present design value makes, at least, a 50 per cent underestimation of reflectivity. To facilitate application of data presented in the far IR, an equation is also correlated that relates the glass hemispherical-total properties with temperature. While the glass properties are also evaluated inside the solar spectrum in this paper, these properties have been reported elsewhere and therefore, are not elaborated. © 1979.