Calculation of Heat Transfer in Condensing Boilers

Thermodynamically irreversible process of heat transfer in low-temperature convective heating surfaces condensing boilers associated with the condensation of water vapour from the combustion of fuel and is accompanied by heat exchange with mass transfer that due to the postponement of the apparent warmth and allocation of latent heat of vaporization. Considering the condensing unit (tail) of the boiler heat exchanger, you can say that condensation will occur on a cooled surface whose temperature must be less than the saturation temperature at constant pressure (i.e. temperature dew point temperature of products of combustion of fuel). On the surface when the water film condensation of variable thickness, flowing under the influence of gravitational forces.