Modeling the Flow and Heat Transfer in a Packed Bed High Temperature Gas-Cooled Reactor in the Context of a Systems CFD Approach

Engineers are faced with two major challenges when carrying out the thermal-fluid design of a complex system consisting of many interacting components. The first challenge is to predict the performance of all the individual thermal-fluid components. The second challenge is to predict the performance of the integrated plant consisting of all its subsystems. The complexity associated with the thermal-fluid design of complex systems requires the use of a variety of analysis techniques and simulation tools. These range from simple one-dimensional models that do not capture all the significant physical phenomena, to large-scale three-dimensional computational fluid dynamics (CFD) codes that, for practical reasons, cannot simulate the entire plant as a single integrated model. In the systems CFD approach, a network code serves as the framework to link the models of the various components together and to control the solution. The models of the components can be of varying degrees of complexity. These can range from simple lumped models to complex fully three-dimensional CFD models. This paper gives a brief overview of the systems CFD (SCFD) approach and an overview of the model of the pebble bed nuclear reactor that was developed in the context of the SCFD approach.