CFD-modelling of subcooled boiling and application to simulate a hot channel of a fuel assembly

The paper contributes to the advanced CFD simulation of subcooled boiling in forced convective flows, with special attention given to the momentum transfer between continuous liquid and vapour bubbles. A wall boiling model, implemented in CFX-5 (Egorov, Menter, 2004) and based on the two-fluid approach, is used here together with the state-of-the-art model correlations for the non-drag forces, available in CFX-5. The paper describes the main concepts of modelling mass, heat and momentum transfer between the phases. Published experimental results for flow in a pipe are used for the model validation.
The model is applied to the simulation of subcooled boiling flow in a hot channel of a fuel rod bundle. Influence of mixing vanes, attached to the spacer grids of fuel assembly in order to enhance the heat transfer, is taken into account. The simulation results demonstrate the capability of the model to estimate the effects of geometrical design on the flow physics.