TOTAL EXCHANGE AREAS FOR RECTANGULAR ENCLOSURES WITH REFLECTING WALLS BY THE DIRECT DISCRETE-ORDINATES METHOD
The purpose of this study is to show that total exchange areas (TEA) for a rectangular box type enclosure can be computed accurately by using the direct discrete-ordinates method (DSN). The medium is either transparent or gray absorbing and emitting. The walls emit diffusely but reflect diffusely or specularly. Symmetric or unsymmetric ordinates sets are used for the results. For both cases, the DSN weights are set equal to the solid angles of the meshes. The effects of optical thickness,- wall emittance, and diffuse or specular reflectance as well as the numbers of spatial and angular divisions on the accuracy of TEA results are studied. The results are insensitive to the choice of the symmetric or unsymmetric ordinates sets. The results agree well with the predictions by the matrix approach. The results by the DSN) method converge to the exact values as the number of spatial and angular division increase.