Numerical Simulation Research of Natural Convection Heat Exchanger
In this paper, computer software is employed to simulate the temperature-field and flow-field of AP1000 PRHR HX, and investigate its heat-transferring and flow characteristic. Through comparative analysis of the distribution of temperature-field and flow-field in different locations at the same time, and the change of temperature-field and flow-field in the same location at different times, heat-transferring process and natural convection situation of PRHR HX are deeply understand. It contributes to analyze the natural circulation capacity of PRHR HX, and provides some references for the effective operation of passive residual heat removal system.
Investigation on transient thermal hydraulics of reduced scale passive residual heat removal heat exchanger in tank
Abstract In advanced nuclear power plant AP1000, the passive residual heat removal heat exchanger (PRHR HX) is a key part of the passive safety system. It can transfer decay heat from the reactor core to the water in the in-containment refueling water storage tank (IRWST) during the accidents. The secure operation of the C-shaped PRHR HX has a great impact on the reactor safety. In the present work, the heat transfer performance of a reduced scale PRHR HX was investigated by experiments and numerical simulations. A system including a 6 × 7 C-shaped tube bundle and a rectangular tank was studied. A three-dimensional numerical model using porous media method was developed to explore the transient single phase thermal hydraulic characteristics of the PRHR HX. The distributed resistances caused by the C-shaped tube bundle were calculated by empirical correlations. Both the heat transfer coefficients from the hot fluid in the tube to the inside surface of tube and that from the outer tube surface to the water in the IRWST were calculated by empirical correlations published in literatures. Tests were performed on the 6 × 7 C-shaped tube bundle installed in the middle of the tank. The outer wall temperature and bulk water temperature in the tank were measured by thermocouples. The numerical methods were validated by the experimental results. The calculated results of the local temperature distribution and heat transfer rate were both well consistent with the experimental values. The deviation of the heat transfer rate was smaller than 5%.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.