Three-Dimensional Numerical Study on Condensation-Conduction-Evaporation Coupled Heat Transfer

In passive containment cooling system on AP-series nuclear power plants, condensation-conduction-evaporation coupled heat transfer is crucial in taking the energy from inside of containment to the outside environment. A numerical study on this heat transfer process is presented in this paper. Condensation film on the containment inside surface and cooling water film on the outside surface are described by a liquid-film tracking model. Heat conduction through containment shell is usually modeled to be one dimensional (1-D) in common thermal-hydraulic computer codes. However, heat is always transferred from hoter regions of the shell to the cooler regions in all directions, and this phenomenon becomes more prominent when the containment surface is not fully covered with liquid film. Three dimensional (3-D) heat conduction in containment shell is carefully studied, and the quantified results are compared to that obtained from 1-D model.