Research on a two-phase condensation model with predictable turbulent film.

Steam condensation containing non-condensable gases is the main method of heat removal under severe nuclear accidents. To investigate the condensation characteristic, several numerical simulation studies have been conducted. Previous numerical models generally assume that the condensate film is thin or even negligible owing to the existence of non-condensable gases. However, the condensation rate improved rapidly as steam concentration rises. As the condensation rate rises, the velocity and thickness of the film will also sharply increase, thereby affecting the condensation process. In this case, the film flow will transition to a turbulent regime. To consummate the condensation model, a two-phase condensation model with predictable turbulent film was proposed. The model can predict the condensation performance well in a broad range, with deviation generally within 20%. In addition, the prediction correlation and contour diagram were obtained to identify the thermal resistance ratio and the flow regime of the film according to the proposed model. • A two-phase condensation model with predictable turbulent films is proposed. • The mechanism of the film effect on the condensation process is revealed. • The distribution of fluid film thermal resistance ratio is given. • The discriminant method of fluid film flow regime is obtained. [ABSTRACT FROM AUTHOR]