Investigations on water condensation in the main steam pipe of a pressurized water reactor nuclear power station: Part II—Theoretical studies

A theoretical method based on heat transfer theories and numerical simulations was presented to predict the water condensation rates in the main steam pipe for the pressurized water reactor nuclear power station during the stable and starting up operation processes. Firstly, the complex heat transfer processes, including the steady heat transfer and transient heat transfer, in the main steam pipe were analyzed in detail. Then, the theoretical prediction methods were presented to compute the heat loss in the main steam pipe during stable and starting up operation processes, respectively. In order to verify the present theoretical method as well as visualize the flow fields in the main steam pipe, corresponding computational fluid dynamics computations based on conjugate heat transfer and equilibrium condensation model were performed. To validate the reliability of the present theoretical method, experiments (see Part I of this two-part paper) were carried out to measure the water condensation rates in the main steam pipe during the starting up and stable operation processes. The comparisons were made between the theoretical predictions, computational fluid dynamics computations, and the experimental tests. It shows that the present theoretical method has a good accuracy in predicting the water condensation rates for these two different operation conditions. For the startup process, the difference between the theoretical prediction and experimental data is only 0.16%. For the stable operation condition, the difference between the prediction and experimental data reaches 30.24% for the theoretical method whereas 23.55% for the computational fluid dynamics method.