Radiative heat transfer in the furnace space with variable volume

The combustion chamber and flues boiler radiant heat exchange occur between the gas (combustion products) and limiting gas surfaces of the combustion chamber and flues. In this case, part of the energy-emitted gas is absorbed by the surfaces, and part of it is reflected into the gas. The resulting heat flow between the gas and the surface defined by the difference between the amount of energy emitted by the gas on the surface, and the amount of energy absorbed by the gas from the radiation surfaces. The article presents the basic formulas for boilers on solid fuel with movable grate. Calculations show that the change in volume of the furnace leads to a change in radiant heat transfer.