Modelling and simulation of fluid flow and heat transfer in the convective zone of a power-generation boiler

The convective zone of a power-station boiler is a complex piece of engineering equipment, which comprises a multiplicity of inter-connected heat-exchanging elements. This paper presents a mathematical model of the convective zone, which allows for the calculation of the shell-side flow and the shell-side, tube-side and tube-wall, thermal fields, and of the shell-tube heat-exchange. The model is solved using conventional CFD techniques, in which the individual tubes are treated as sub-grid features. A geometrical model is used to describe the multiplicity of heat-exchanging structures, and the interconnections among them. The CFD model is first validated by comparison with simple heat exchanger geometries which can be solved with analytical methods, and then applied to an actual 350 MW(e) power-station boiler.