The P-1 model for thermal radiation transfer: advantages and limitations

The P-1 model for thermal radiation transfer is re-examined in view of its potential applications to industrial problems as part of a computational fluid dynamics (CFD) analysis. The concept of radiation temperature adopted is shown to be particularly useful when this model is used in a general curvilinear coordinate system. An explanation is given as to why the P-1 model gives reliable predictions in the case of 1D plane geometry in both optically thin and optically thick media, while it overestimates the radiation heat fluxes from localized heat sources in optically thin media. It is pointed out that the P-1 model is particularly useful for accounting for the radiative exchange between gas and particles. The results of modelling of coal combustion processes in an industrial furnace based on the P-1 model are shown to be consistent with experimental observations.