BANDED RADIATIVE HEAT-TRANSFER ANALYSIS

Recent work has shown that many ceramic fibres which are increasingly used to line industrial furnaces have highly spectral-dependent emissi vities. This paper presents an extension to the standard zone method f or radiative heat transfer calculations which directly models spectral variation in surface and gas properties. A short description of the z one method is given along with a summary of the weighted sum of grey g ases model. This is often used as a means of representing the temperat ure dependence of total gas properties brought about because of the sp ectral non-uniformity of these properties. When surfaces as well as th e gas are non-grey, a new approach is required. The method of this pap er is based on dividing the spectrum into a number of bands and treati ng the properties as constant within each band. This method can be use d directly if the boundary conditions specify ail the zone temperature s. However, if some temperatures are unknown, then an iterative soluti on technique is required. Results of some sample calculations are pres ented, These illustrate the importance of directly modelling the spect ral behaviour of gas and surface properties. (C) 1997 John Wiley & Son s, Ltd.