1 THE SIMULATION OF A THERMAL-FLUID SYSTEM USING AN INTEGRATED SYSTEMS CFD APPROACH

Complex thermal-fluid systems may consist of many interacting components such as pipes, heat exchangers, turbines and boilers. The first of two major design challenges is to predict the performance of all the thermal-fluid components on the system level and the second is to predict the performance of the integrated plant consisting of all its sub-systems. The solution to both is an integrated Systems CFD (Computational Fluid Dynamics) approach that deals with various levels of complexity between individual models. To account for the interaction between components on system level a progressive approach can be followed by first using lumped models for all components and then refining individual models where necessary. To illustrate the application of a progressive analysis, this paper presents the practical example of a coal-fired boiler at a power station. A one-dimensional pipe network was used to determine the quality of the steam mixture and the heat transfer in the boiler riser tubes and these were linked to the detailed three-dimensional CFD model of the furnace. Results from the CFD model showed gas flow patterns and heat distributions inside the furnace. From the network model the temperatures and steam quality inside the riser tubes were obtained and it illustrated the process of steam generation inside the riser tubes