Analysis of film boiling heat transfer during fuel-coolant interaction

The aim of the paper is to discuss the heat transfer modelling approaches applicable for the fuel-coolant interaction codes. First, the applicability of the adjusted Epstein-Hauser correlation for the film boiling modelling is analysed either comparing the correlation to the experiments with water or analysing the sodium properties. In the paper two modes of the film boiling regime are discussed. Indeed, experiments performed with the sub-cooled water have indicated an increase in the heat transfer between the stable and unstable mode. The numerical correction factors of the adjusted Epstein-Hauser correlation are proposed for the stable and unstable modes of the film boiling regime. Second, for the stable mode of the film boiling regime a modified Epstein-Hauser correlation is proposed to enable better general matching with the experimental data at significant sub-cooling. Next, for the unstable mode an alternative correlation is proposed and assessed. Finally, the empirical correlation for defining the transition from the film boiling regime towards the transition boiling regime is used to discuss the relevance of the unstable mode or transition boiling regime modelling in sodium. For sodium, additional experiments should be performed.