Validation of the interfacial area transport equation coupled with the void transport equation for prediction of flashing flows

The benchmark of the interfacial area concentration (IAC) correlations, as well as one and two-group formulation of the Interfacial Area Transport Equation (IATE), with a new flashing flow dataset is presented. The correlations are observed to consistently overpredict the IAC, especially under elevated pressure conditions. The predictions by the one-group IATE also show a dependence on pressure with the IAC in low-pressure conditions being severely overpredicted. The inadequacy of the correlations and the one-group IATE in handling flashing flow highlights the need for a two-group approach to capture the different mechanisms that govern large cap/slug bubbles. Several Nusselt number correlations are validated and the results are compared. A characteristic length-scale based on the thickness of liquid film in high void fraction flow is proposed for the calculation of Group-2 mass generation rate. The analysis shows that even though the predictions by the two-group IATE are also pressure-sensitive, the accuracy improves drastically compared to the correlations and one-group approach.