OCR Text |
Show In the case that the element / is a surface elemnet, the outlet intensity of the radiative heat ray is determined by the proportion to the inlet intensity of the radiative heat ray and emissivity of the element / . *out,k-*l ~ lin,k-+lV ~ £i) ('' When the radiative heat ray meets the surface, it reflects back into the gas media in the direction determined by the Lambert cosine law. This direction is determined using two pseudo random numbers. Above implementations are continued until the intensity of the radiative heat ray becomes 0.001% of initial intensity of the ray in this study. As a result of the procedure, the R E A D and the self absorption ratio are calculated in following equations. «<^=2>Ly{Ar(l-a,)} (8) The direct exchange area should satisfy following relations, otherwise unreasonable heat generation or dissipation (equation (10)) and unreasonable heat exchange between two elements whose temperatures are identical (equation (11)) occur. V *"*' \skSk (Arforiv, sandm) (10) O M = DM (11) In this study, in order to satisfy these two relations the R E A D and the self absorption ratio have been corrected using the operation suggested by Omori [4]. At the end of this part, following three assumptions introduced here in order to simplify the analysis are listed. 1. Gas and surfaces are gray media. 2. There is no scattering in gas. 3. The radiative absorption coefficient of gas and the emissivity of surfaces are spatialy constants. |