Effect of Reradiation on Heat Transmission in Furnaces and Through Openings

Abstract

In heat transmission by radiation, the reradiation of heat from adjacent surfaces has been a perplexing question. Radiation of heat through openings in furnace walls, radiation in electric furnaces having heating elements under the roof only, and radiation in some types of oil stills from muffles on the floor to the tubes under the roof are all cases in point. In this paper accurate methods of calculation are developed, and curves are presented from which the reradiation and total radiation factors can be read at a glance, for various shapes and proportions of radiating surfaces or openings. Incidental to the chief results, two methods of solving integral equations are presented. The theoretically developed values are checked and substantiated by actual test measurements.