Research On Heat Transfer Mechanism And Experimental Verification Of Passive Residual Heat Removal Heat Exchanger

Westinghouse advanced passive pressurized water reactor AP1000is based on the design of AP600. Its security system is designed to take full use of the natural driving force. It can maintain normal operation of the nuclear power plant without the need for large-scale security system. The use of passive systems make the nuclear power plant significantly simplified compared to a traditional PWR nuclear power plant. It reduces the amount of the purchase of equipments, lower the installation costs, shorten the construction cycle and minimize maintenance activities.In order to master the heat transfer characteristics of AP1000PRHR HX and explore the heat transfer model and thermal calculation method, in this paper, the heat transfer mechanism of the PRHR HX has been analysed and researched, the main forms of heat transfer were determined on both sides of the heat exchange tube under the design condition. The experimental system for simulating PRHR HX was built, the tube inside single-phase convection heat transfer characteristics and the tube outside natural convection、subcooled boiling、saturated boiling heat transfer characteristics were studied by experiments.(1) In the experiment of tube outside natural convection, for the tube inside single-phase convection, Dittus-Boelter correlation is the best-estimate fit correlation for tube inside single-phase convection of PRHR HX. McAdams correlations are the best-estimate fit correlations for the tube outside natural convection heat transfer correlations of PRHR HX.(2) In the experiment of tube outside boiling, the tank fluid rose gradually which lead to a thermal stratification phenomenon. Researching the IRWST heat sink thermal stratification interface change rule, the PRHR HX heat transfer mechanism of the heat sink was proposed, and the heat transfer mechanism was verified by using the experimental data in the literature.The achievements of this project could provide theoretical supports for the design of PRHR HX of advanced PWR nuclear power plant. It will push the localization of Westinghouse AP1000in China greatly, at the same time, improve the CAP1400research and development, which is a larger capacity nuclear power plant with independent intellectual property rights of China.