Numerical investigation on the thermal stratification in a pressurizer surge line

Thermal stratification is a common phenomenon in the surge line of Pressurized Water Reactors (PWRs). A study using Computational Fluid Dynamics (CFD) has been performed to analyze the thermal stratification in the pressurized surge line with different surge line and main pipe velocity conditions. This study is typical of considering both the flow subjected to the buoyancy and the conjugate heat transfer between the fluid and the pipe wall. What makes the research complex is exactly the impact of buoyancy on thermal stratification. To validate the accuracy of CFD calculations, necessary comparison is performed with experiment results. Models with different computational conditions resulting from various similarity criterion parameters are used. More meaningful information than that from the experimental results can be obtained. At the same time, many actual operating conditions which are difficult for experiment can be also accomplished by applying CFD mode. Temperature distributions inside and on the outer surface of the surge line are provided by the CFD mode with different turbulent models. Compared to the standard k-ɛ turbulence model and Reynolds stress model (RSM), the SST k-ω turbulent model is more adapted for this study. Based on the conclusion, the numerical results with the SST k-ω turbulence model for the prototype on the actual nuclear power plant unit were mainly described.