Investigation of radiative heat transfer in freeboard of a 0.3 MWt AFBC test rig

Based on the analysis of measured data on flow rates, concentrations and te mperatures taken during steady state operation of a lignite-fired 0.3 MWt A tmospheric Fluidized Bed Combustor (AFBC) test rig, radiative exchange in f reeboard of the combustor was modeled by using a well-stirred enclosure mod el in conjunction with Radiosity-Irradiation Method (RIM). Radiative proper ties of the particle laden combustion gases were calculated by assuming gre y radiation behaviour for both particles and gas, and using Leckner's corre lations for gas and Mie theory for particles. The accuracy of the model was tested by comparing its predictions with incident radiative heat fluxes me asured on the freeboard wall. Comparisons between the incident radiative he at fluxes predicted by the present model and those measured show that this engineering approach can be used with confidence by designers for the parti cle loadings typically encountered in freeboards of bubbling fluidized bed combustors.