Numerical simulation and parameter sensitivity analysis of coupled heat transfer by PCCS containment wall

Abstract After Fukushima nuclear accident, enhancing the nuclear safety with passive features is attracting more and more attentions. The complex coupled heat transfer process by the passive containment cooling system (PCCS) containment plays an important role in several kinds of nuclear plant. In order for understanding the characteristics of the process of coupled heat transfer by PCCS containment wall, a one-dimensional steady numerical model is proposed in the present study based on physical features and valuated empirical correlations of relevant sub-processes. In the proposed model, steam condenses on the inner surface of a steel plate, while cooling water flows as a thin film along its outer surface and evaporates on the surface of the liquid film. A counter-current cooling air flow, acting as the cold source, exists in the gap between the liquid film and an air baffle. The model is validated by comparing with experimental data reported in the literature. Parameter sensitivity analysis is carried out to reveal the influences of various parameters on the coupled heat transfer process. It is shown that, according to the importance, these factors can be listed, from high to low, as the follows: mixture pressure, cooling air velocity and its temperature, cooling water line flow rate and gap width of air channel, and wall inclined angle. The results can be helpful for the design and engineering applications of PCCS containment in the future.