TheThermal radiation most important approaches to modelling the effects of thermal radiation in CFD codes are described. It is pointed out that, in contrast to conduction and convection, heat transfer by thermal radiationThermal radiation takes place not only from neighbouring cells, but also from the cells located at large distances from the cell under consideration. Also, radiative heat transferRadiative heat transfer to a specific cell takes place from an infinite number of directions. This leads to a requirement for the discretisation of the directions from which thermal radiationThermal radiation approaches this cell. Two approaches to the latter discretisation are described: one based on averaging of the radiation intensityRadiation intensity in a certain range of solid anglesSolid angles and the one based on the expansion of the radiation intensityRadiation intensity in an orthogonal seriesOrthogonal series of spherical harmonicsSpherical harmonics. Particular attention is focused on the latter approach leading to the \(P_N\) model model. It is shown that the limiting version of this model, known as the \(P_1\) model, is particularly attractive for the implementation in CFD codes. The limitations of the model of droplet heating, based on the assumption that the droplet is an opaqueOpaque greyGrey sphere, are discussed. A model considering the radiative heating of droplets by thermal radiationThermal radiation is described.