Measured angular distribution of the emissivity and calculated radiation heat transfer of architectural coated flat glass Part 2. Results and discussion

Abstract

The angular emissivity curves of 10 representative architectural coatings and of uncoated float glass are measured at 283 Κ with the help of an angular emissometer up to an angle of 70°. The experimental values can be fitted with the help of Fresnel's equations for a single, optically thick material, and extrapolated up to 90°. The obtained curves are integrated and the results compared with the values computed according to several drafts of standards in course of approval. The principle of computing the hemispherical and effective emissivity from normal emissivity with the help of a suitable multiphcative coefficient is found to be in substantial agreement with the experimental evidence.