ABSTRACT
For the purposes of computing radiant interchange, engineering surfaces are almost always idealized as diffuse emitters and diffuse reflectors of radiant energy. This chapter describes the methods of analyzing the radiant transport between such surfaces. Black surfaces are treated here inasmuch as they are perfect diffuse emitters although they do not reflect at all. The chapter analyses radiant interchange among black surfaces and explains the effect of wavelength-dependent radiation properties. It presents two concepts which are common to all the material. The first is the idea of the enclosure. In calculating the radiant interchange at any surface, it is necessary to include radiation arriving at that surface from all directions in space. The second concept that is to be used frequently in the forthcoming development is the angle factor. The analysis of radiant transport among gray, diffuse surfaces can be formulated at various levels of complexity, depending on the effort that is to be expended in solving the problem.
