Directional total emittance of three hard-coated glasses at 283 Κ

Abstract

The directional total emittance at 283 Κ of three hard-coated glasses of medium to low emittance was measured over the angular range 10° to 84°. The measured values at 10° a r e 0.137 ± 0.003, 0.309 ± 0.006, 0.630 ± 0.008. The angular variadon correlates with these values: The lowest emittance glass is quasi metallic; the highest emittance glass is quasi dielectric; the intermediate glass is weakly metallic. Directional data are needed for the most accurate type of modelling of the thermal behaviour of glazing, and can also be used to refme the correction tables needed to obtain the corrected emittance from the normal emittance.