| Special electric actuation system is the servo mechanism for power regulation and system protection,and is the only dynamic equipment in the reactor structure.During the normal operation of special electric actuation system,while the copper consumption of the coil is caused by power on,the heat transferred to the coil by the internal coolant in the travel sleeve due to thermal siphon increases its temperature,which will cause aging and even failure of the coil.Therefore,in order to ensure the reliability of special electric actuation system in operation,it is necessary to calculate and analyze the maximum temperature that the coil can reach under the working state.Taking the special electric actuation system of pressurized water reactor as the main body,this paper adopts computational fluid dynamics and finite element analysis methods,and takes into account the natural convection of the external air and the thermal siphon of the internal coolant of the special electric actuation system,simulates and calculates the whole temperature field of the special electric actuation system,and studies the temperature rise at the natural cooling coil of the special electric actuation system without air cooling system,The steady-state temperature distribution changes of special electric actuation system under different conditions are discussed,taking into account the natural convection of external air and the thermosiphon of internal coolant,such as the insertion depth of special electric actuation system,ambient temperature,maximum power operation,etc.And through two different numerical calculation methods and experiments,the simulation is carried out to verify the processing methods and results in the study.Firstly,based on the heat conduction model,heat convection model,boundary condition determination,heat source determination and thermal conductivity and heat dissipation coefficient determination,the two-dimensional and three-dimensional temperature field models are established by using the finite element analysis method.Its heat source and thermal conductivity and heat dissipation coefficient will change with the environment and operating state.The temperature rise in the initial state will affect the copper loss,iron loss,hysteresis loss and eddy current loss on the core.The change of loss will directly affect the change of temperature field and heat source,and then affect the temperature field of the whole driving mechanism.By establishing the coupling relationship between electromagnetic field and temperature field in the mechanism.Then,the three-dimensional temperature field finite element model of special electric actuation system is built to analyze the steady-state temperature field distribution and transient temperature rise curve under the working conditions of lifting,stepping,lowering and rapid rod dropping,and to study the steady-state and transient global temperature rise characteristics of the coil in special electric actuation system.And,considering the natural convection heat transfer of external air and the phenomenon of internal thermosiphon,the temperature rise of the inner coil of special electric actuation system is simulated and analyzed.Using the results of thermal path analysis,the average temperature of each component at the coil is analyzed and compared with the finite element results to ensure the correctness of the whole process of modeling and Simulation of the temperature at the coil.Finally,based on the special electric actuation system lifting coil part,the temperature field analysis test-bed is built.By comparing the experimental and simulation results,it is verified that the simulation grid and modeling are basically correct and in line with the reality when considering the natural convection and heat dissipation of external air.It lays a foundation for further research and optimization of the analysis method of temperature field and accurate expression of its temperature change. |
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