Comparisons of condensation models with non-condensable gases for computational fluid analyses

One of the challenges in the computational fluid dynamics (CFD) code to analyze the two-phase flow with phase changes such as condensation or boiling which has a particular importance in nuclear safety analyses. We developed three wall condensation models to calculate the mass flux of vapor or heat transfer coefficient due to condensation at the wall-nearest cells in the presence of noncondensable gases for CUPID which is a kind of CFD codes, in order to provide options for users, depending on the condensation conditions. The three models are a mechanistic model based on the diffusion theory, semi-mechanistic model utilizing the heat-and-mass-transfer analogy (HMTA), and empirical correlation model. The models were benchmarked with COPAIN experiments in order to validate the models and find out their usability. It was found that mechanistic model was recommendable while the HTMA model would better predict condensation phenomena in particular cases.