ANALYSIS OF TEMPERATURE DROPS ON THE WALL THICKNESS OF A SUPERCRITICAL BOILER WATER-WALL TUBE

The paper presents selected results of numerical computations related to simulations of a supercritical power boiler evaporator operation. A detailed analysis is carried out of temperature drops on the thickness of the water-wall tube and the tube fin. A comparison is also made between the results obtained at the fin division into one and two control volumes. The tube cross-sections analysed along the tube length and including the fins are divided into 24 control volumes, for which 2-D transient heat conduction equations are formulated. The 1-D equations describing the principles of mass, momentum, and energy conservation are solved on the side of the working fluid. A convective condition, described by an empirical heat transfer coefficient, is set on the water-wall tube inner surface. The developed mathematical model is a distributed parameter model. The numerical computations are performed for a boiler operating in a power plant in Poland. The analysis takes account of the non-uniformity of the furnace chamber thermal load along its height.