Assessment of Effect of Bubble Departure Frequency in Forced Convective Subcooled Boiling

Abstract

Bubble departure frequency is one of the important parameters for the prediction of subcooled flow boiling. This present work aims at an assessment of bubble departure frequency by investigating the physical mechanisms of three-dimensional two-fluid model coupled with the population balance equation. The CFX MUltiple-SIze-Group (MUSIG) model is used to predict bubbly flows with the presence of heat and mass transfer processes, particularly in subcooled boiling flows at low pressures. The assessment is carried out for these three models/correlations. The test shows that Podowski et al.'s model, with reasonable physical characteristics, is more realistic than the other two models when compared with the experimental data. The numerical results indicate that the higher the departure frequency, the lower the wall temperature and so the nucleation site density. In addition it is found that for both the axial and radial cases the curves of the void fraction tend to decrease with increase in departure frequency. The benchmark of the current numerical simulation with experimental data in both axial and radial profiles achieves successful agreement