Research On Fluid Network Simulation Of Second-loop System Of Nuclear Power Plant

With the rapid development of nuclear energy,the simulation technology for the secondary-loop of nuclear power plant is becoming more and more important.The simulation technology for the secondary-loop of nuclear power plant can not only be applied to the simulator of nuclear power plant,but also be used to simulate the operating conditions that are difficult to realize in reality.Therefore,it is of great significance to carry out corresponding simulation technology research.In this paper,firstly,the simulation model of the pipe network system is studied.A homogeneous flow model and a two-fluid model are established for the pipe network system with different working medium.The homogeneous flow model uses single-phase working medium such as gas,water,oil and water vapor and multi-component working medium uniformly mixed,and the two-fluid model is suitable for steam water two phase flow.In order to realize the simulation of the pipe network system with different working medium,the open source property Coolprop is adopted to realize the query and calculation of the property of different working medium.The homogeneous flow model and the two-fluid model are based on three conservation equations.Meanwhile,the heat transfer and mass transfer equations are established for the two-fluid model.Finally,by linearizing the conservation equation,the solution matrix of the simulation model of the pipe network system is established,and LU decomposition method is used to solve the matrix,so as to realize the solution calculation of the pipe network system and obtain the distribution of the pressure,temperature and enthalpy of the pipe network system.In order to realize the simulation of the main equipment of the second circuit,this paper firstly establishes the simulation model of the main equipment of the second circuit,including the pump,valve,steam turbine,condenser,oxygen eliminator,water heater,soda separation reheater and other equipment.At the same time,according to the main concerns of these devices in the second-loop system of nuclear power plant,the coupling method of the content coupling method or the data coupling method is selected to establish the coupling model between the network system and the equipment and the network system,and the joint solution of the equipment and the network system is realized.In the end of this thesis,the testing and verification of the fluid network is carried out.In the second-loop system of 900 MW PWR nuclear power plant as the object,separately to the second-loop system of each subsystem are simulated,including steady-state data comparison and trend of the transient analysis,simulation model of the fluid network simulation ability,finally will each subsystem together,the overall secondary circuit simulation calculation,the accuracy of the secondary loop system is verified.