Numerical Simulation Of Condenser Based On One-Dimensional And Three-Dimensional Coupling Method

Condenser is an important part of condensing steam turbine.From the perspective of thermal cycle efficiency,the condenser provides back pressure to the steam turbine,which directly affects the final parameters of the thermal cycle system of the power station,and has an important impact on the thermal cycle efficiency.From a safety point of view,the condenser can store the water in the process of starting and stopping and normal operation of the system,and can condense the bypass exhaust steam during the load shedding process.The heat trap of the condenser can buffer the flow of the unit and enhance the stability of the system.Therefore,condensers have an important impact on the economics and safety of nuclear power plant.The double inlet condenser is one of the important equipment for nuclear power plants,and its transient operating characteristics are worth studying.At present,the lumped parameter method,the partition model or the distributed parameter method are used to simulate the transient of the condenser at home and abroad,but these methods do not show the internal flow field of the condenser.In this paper,the numerical simulation of flow field visualization,high simulation accuracy and strong adaptability is used to simulate the transient state of the condenser.The dynamic working characteristics of the double inlet condenser are studied and the flow field distribution is analyzed.The boundary conditions of the transient numerical calculation have great influence on the calculation result.The condenser throat is directly connected with the low pressure cylinder of the steam turbine.The inlet boundary condition of the condenser is inseparable from the working condition of the steam turbine.In this paper,the self-written coupling program is used to couple the turbine model with the condenser model.The condenser is simulated by 3D CFD software,and the steam turbine is simulated by one-dimensional system simulation software to realize one-dimensional and three-dimensional coupling calculation.Provides more accurate inlet boundary conditions for the condenser to improve the accuracy of transient numerical simulations.In this paper,the heat transfer characteristics of the double inlet condenser shell side are simulated by Fluent software.The pressure and velocity distribution of the double inlet condenser are obtained.The effects of air concentration and cooling water inlet temperature on the working performance of the condenser are studied.Then,the one-dimensional system simulation software Flowmaster is used to simulate the working characteristics of the steam turbine.The interface program is written in C# language to realize the bidirectional coupling between Fluent software and Flowmaster software.The steady state calculation is performed on the coupled model.The analysis results show that the initial boundary conditions affect the convergence speed and convergence of the coupling calculation.In the coupled data transfer process,the data transmitted is that the condenser average pressure and the inlet pressure have little effect on the coupling calculation.Finally,the transient calculation of the coupled model is carried out to obtain the dynamic response of the double inlet condenser when the operating conditions such as steam load,circulating cooling water flow and extraction port pressure are changed.The analysis of the transient calculation results shows that the decrease of the steam load will cause the condenser pressure to drop,and the pressure dynamic response has a delay;reducing the circulating cooling water flow will cause the condenser pressure to rise rapidly,and the pressure change rate is related to the flow rate change rate;When the working condition of the main steam inlet is greatly changed,the back pressure at the auxiliary steam inlet changes accordingly,but the variation range is controlled within a reasonable range and will not affect the safe operation of the auxiliary steam turbine.In summary,this paper realizes the onedimensional and three-dimensional coupling calculation of double inlet condensers.The simulation can obtain the flow field distribution and working characteristics of the condenser,and provide reference for its design and improvement.