Adaptation of differential equation of the energy to conditions of furnace processes in the boiler units

The paper presents the form of a differential equation of energy for the flow in the furnace of the boiler unit. This form takes into account the mechanisms of heat transfer significant for this case. Examples of such mechanisms are convection, radiation, heat conductivity and volumetric generation of heat. Heat transfer coef-ficients adapted to the real conditions of the process. Their physical meanings and limits of variation are revealed in the paper. In addition, the authors define the similarity numbers and intervals of their impact on spatial temperature field of the boiler furnace, regimes of the flow, heat transfer in the contents of furnace volume. It is shown that if the observed practical values of the optical density of the medium in the boiler furnaces are 2.8-3.6 then for the mathematical description of the radiation flux density vector the transition is possible from spherical dependence to the gradient dependence. Also, the gradient form is recommended for convection-conduction mechanism of the formation of temperature moles in the boiler furnaces. The areas of transition to the turbulent regime in the boundary layer, the scale of the turbulent fields in this case rises up to 0.3 m. The paper specifies the effect of temperature of the flow on its thermal and physical properties.