Radiation Heat Transfer in Semigray Enclosures With Specularly and Diffusely Reflecting Surfaces

Abstract

The calculation of radiation heat fluxes in an enclosure of plane, gray surfaces with an arbitrary number of specularly reflecting and diffusely reflecting areas is cast into a form convenient for engineering design purposes. The image analysis of Sparrow, Eckert, and Jonsson is utilized to define a set of shape functions analogous to the familiar shape, or angle, factors used in enclosures which consist of diffuse surfaces only. The shape functions are used to derive a coefficient equivalent to Hottel’s gray body factor, F. The present analysis is extended to include interreflection phenomena with semigray surfaces which are postulated to emit energy in one spectral region and absorb energy in a different spectral region. Examples are given to indicate the utility of the present formulation for performing parametric design studies of complex enclosures and space vehicles.