Numerical investigations on the coupling of the one-group interfacial area transport equation and subcooled boiling models for nuclear safety applications

The one-group interfacial area transport equation (IATE) was coupled to a wall heat flux partitioning model in the framework of two-phase Eulerian approach using the OpenFOAM CFD code for better prediction of sub-cooled boiling flow. The IATE was modified to include the effect of bubble nucleation at the wall and condensation in the bulk region that governs the non-uniform bubble size distribution. To validate the capability of the newly developed OpenFOAM solver, it has been used to simulate the upwards sub-cooled boiling bubbly flow in the DEBORA test facility. Predictions of the gas volume fraction, gas velocity, bubble Sauter mean diameter and liquid temperature profiles were in a good agreement with the experimental data. Simulation results of the DEBORA experiment achieved with the MUSIG model implemented in the ANSYS CFX code in other work have been compared to the simulation results by the IATE model implemented in OpenFOAM to test the competence of the one-group IATE to provide good prediction of subcooled boiling flow parameters. Both approaches were found to provide compatible results.