Validation of the Interfacial Area Transport Equation Coupled with the Void Transport Equation for Prediction of Flashing Flows

The static correlations from RELAP5 and TRACE as well as the interfacial area transport equation (IATE) are benchmarked for flashing flow with selected cases from a recently published experimental data set. The RELAP5 correlation is able to predict the interfacial area concentration more accurately than the TRACE correlation. The one-group decoupled IATE, supplied with experimental void fraction, shows overprediction of interfacial area concentration, especially at low-pressure conditions. Additionally, the one-group IATE is solved simultaneously with the void transport equation where at low pressures, the accuracy of the predicted interfacial area concentration improves even with the void fraction being underpredicted. However, as the pressure increases, the improving accuracy of the predicted void fraction leads to an overprediction of the interfacial area concentration. The two-group IATE is also benchmarked, first using the interfacial mass generation model from RELAP5 and TRACE and then with a model derived through a mass-energy balance approach. The accuracy of the two-group IATE is observed to be sensitive to the choice of the heat transfer length scale and Nusselt number correlations.