ABSTRACT
Radiant exchange between gray surfaces with directional properties is considered. Radiation exchange between infinite parallel plates, concentric cylinders, and concentric spheres, is of practical importance for predicting the heat transfer performance of radiation shields, Dewar vessels, and cryogenic insulation applications. For specular reflections, the directionality of the emitted energy is retained throughout the exchange process for the parallel-plate geometry. The difficulty in treating the general case of directionally dependent properties is illustrated by performing an energy balance in a simple geometry: The radiative exchange between two infinitely long parallel nondiffuse gray surfaces of finite width. A surface with part specular and part diffuse reflectivity and a semigray analysis were used by Shimoji to find local temperatures in conical and V-groove cavities exposed to incident solar radiation parallel to the cone axis or V-groove bisector plane.
