Wright, Seanr2024-08-152024-08-1519981998https://hdl.handle.net/1828/20198The objectives of this work are to improve the understanding and also to simplify the calculation of the entropy transferred by thermal radiation (TR). Thermal radiation plays an important role in the thermodynamic analysis of many systems. For example consider the Earth. Thermal radiation exchange is frequently the dominant form of energy and entropy transfer within the Earth system and is the only significant form of exchange between the Earth and the universe ([15], p. 38,39). Moreover, radiation-matter interaction is responsible for most of the entropy produced by the Earth system. With respect to the energy of TR there has been extensive research and application in engineering analysis. The entropy of TR with an arbitrary spectrum can be calculated by numerical integration using Planck's [1] fundamental spectral entropy radiance (LJ expression. This requires the knowledge of the spectral energy radiance (KJ spectrum with position and direction. Exclusive use of numerical integration is straightforward but laborious and from an analytical perspective the entropy of non-blackbody radiation (NBR) is not well understood. Heat transfer textbooks usually exclude entropy altogether. Furthermore, most thermodynamic texts are misleading because they state that the entropy flux of 'heat' transfer is the ratio of the energy flux to the local temperature ( q/T) with no restriction for TR (e.g. Moran and Shapiro [2], p. 220 and 230; Reynolds and Perkins [3], p. 223; and McGovern [4], p. 177).82 pagesAvailable to the World Wide WebThesis