Exact and Mean Beam Length Calculations For Radiative Heat Transfer in Gases

摘要

This note examines the validity of the mean beam length technique, which is an approximate engineering method for calculating radiative heat transfer in furnace gases. Exact and mean beam length results are compared for laminar flow of carbon monoxide between parallel black surfaces. The results show that the mean beam length calculations overestimate the heat transfer by 47 per cent. This approximation gives better results than other approximate techniques used such as the gray gas and optically thin approximations. Further work is needed to determine the validity of the mean beam length technique in more complicated geometries, and when gas mixtures are present.