CFD investigation on start-up transient of HPR1000 secondary side passive residual heat removal heat exchanger.

• The transient thermal hydraulic performance of the Secondary Side Passive Residual Heat Removal Heat Exchanger (SPRS HX) in the HPR1000 reactor is simulated using computational fluid dynamics (CFD). • The C-shape tube bundle is modeled using the porous media approach along with the distributed resistance method. • The two-phase flow phenomenon in the cooling water tank (CWT) is simulated by the drift flux model. • Three dimensional distributions of fluid temperature, velocity and void fraction in the CWT are obtained. • The SPRS HX heat transfer capacity from the primary side to the secondary fluid is determined. In advanced pressurized water reactor HPR1000, the secondary side passive residual heat removal heat exchanger (SPRS HX) is a crucial component. It removes the decay heat using boiling and convection heat transfer in the event of accidents. The robust functioning of the SPRS HX significantly influences overall reactor safety. To investigate the thermal hydraulic attributes of SPRS HX, computational fluid dynamics (CFD) is used in this study. The tube region is simulated using the porous media method (PMM). To model the two-phase flow in the tank, the drift flux model (DFM) is employed. The assessment of heat transfer rate from the primary to the secondary sides is conducted by empirical correlations. The governing equations are addressed through the utilization of FLUENT. Specifically, the momentum and energy equations are augmented with additional source terms that account for flow resistance and heat transfer in the tube region. These modifications are enacted through User Defined Functions (UDF). Three-dimensional profiles of the void fraction, fluid temperature and velocity are acquired, allowing for a comprehensive analysis of the heat transfer attributes of tube region. [ABSTRACT FROM AUTHOR]