Study On Thermal-Hydraulic And Thermal-Stress Analysis Of The Horizontal Steam Generator

Nuclear power, as a kind of green and efficient new energy, becomes an important part of China's energy strategy. In the next few years, China will focus on developing nuclear power technology. However, the nuclear safety issues has been the major obstacles on the way of nuclear energy development, and any safety accident may lead to serious consequence which makes it rather necessary and crucial to improve the security and reliability of nuclear power plant during the operation process. Reactor steam generator is one of the three key nuclear power plants equipment, The Steam generator is the hinge that connects the primary and second loop of Nuclear Power Plant as well as the barrier that separates the medium of the two loops. Therefore, studying the laws of the steam generator thermal hydraulics is an effective way to improve the efficiency of the equipment, protect equipment damage and maintain equipment safety.Horizontal steam generator, with complicated structure under high temperature, high pressure and thermal shock load, contains ever-changing physical phenomena such as complex gas-liquid two phase flow, boiling heat transfer, natural circulation, forced convection heat transfer, fluid-structure interaction as well as desiccation during the running process, which make the structure safety rather a serious problem. The lack of experimental equipment and hard measure of operation data make numerical analysis become an important research technique, while it is still a tough task to consider the physical phenomena of horizontal steam generator integrated in three dimensional numerical simulation, so far, rarely to see the domestic studies about three dimensional thermal-hydraulic analysis of the horizontal steam generator, and foreigners only work on the simplified model, which needs to improve the accuracy of results.This paper adopts the fluid simulation software Fluent and the structure analysis software Ansys to the simulation analysis of steady flow field and temperature field as well as the numerical calculation of the transient stress structure of the horizontal steam. First, a detailed model of the steam generator cross-section was built by using the Fluent to calculate the two-dimensional flow field. Then simplify U-shaped heat transfer tube bundle and perforated plate based on the porous medium model to establish a three-dimensional CFD mode, in which the evaporation condensation, primary and secondary loop coupling heat transfer and the dryer model are realized by user-defined functions(UDF) of Fluent, further, to analysis the three dimensional flow field and compare the calculation results of two-dimensional and three-dimensional model. At last, we calculated the thermal stress of the structure by using Ansys with the Fluent results as initial conditions and the RVE analysis method was applied to simplify the perforated wall where the tubes and the collector connected. The results show that the means in this paper can simulate the heat-transfer characteristic well, and the RVE method greatly reduced the difficulty in modeling the local structure of the collector, as well as the computation scales. In this paper we obtain the stress state of the key structure, these were the basis for strength assessment and fatigue life analysis of the steam generator.