Steam Boiler by International Energy Agency and Georges Liebecq A steam boiler transforms water into steam. The necessary energy is provided by combustion of a fuel of known composition. Most often, the flue gas resulting from the compustion process exchanges heat with the water through an economizer pre-heating the water, the evaporator and a steam superheater. Given a steam demand (i.e. mass flowrate, temperature and pressure) and inlet conditions for the supply water, TYPE 57 computes the fuel consumption, the flue gas stack temperature and the boiler efficiency, taking into account: -losses to flue gas; -losses by radiation and convection to the environment; -losses due to continous blowdown (water extraction to the purity of water); -losses to the ashes extracted from the furnace at a temperature close to the combustion temperature. The model computes first a theoretical adiabatic combustion temperature and the composition of the flue gas. Then, it considers the boiler as a counterflow heat exchanger between flue gas and water. Its UA-value (for nominal conditions) may be given by the user or can be computed if the stack temperature is known. Ref:A Simple Steam Boiler Model for TRNSYS; G. Liebecq June 1988 (Type 57 File)