Evaluation of the Net Radiant Heat Transfer between Specularly Reflecting Plates

Abstract

The radiant heat transfer between two parallel infinite plates was determined. The plates were assumed to be specular, anisotropic reflectors and emitters as characterized by the electromagnetic theory for highly polished electrical conductors. Numerical results are given for specific metals from 4.2 to 1500° K. Also, the results are expressed in generalized form for obtaining the net radiant heat transfer between any two parallel, infinite metal plates given only the temperatures and electrical resistivities. Total hemispherical and normal emissivities were determined using the same methods. The results were in very good agreement with empirical equations given in the literature. For a contrasting comparison, Christiansen's equation for the net radiant heat transfer between two parallel, diffuse, gray surfaces of infinite extent was evaluated using these emissivities. The values obtained were less than those computed for the net radiant heat transfer between specular plates.