核电站冷却塔动态仿真及冷却特性研究

发布时间：2018-03-06 03:04

本文选题：内陆核电站　切入点：自然循环逆流湿式冷却塔　出处：《哈尔滨工程大学》2014年硕士论文　论文类型：学位论文

【摘要】：与沿海核电站循环冷却系统采用的开式循环方式不同,内陆核电站循环冷却系统基本采用冷却塔闭式循环冷却方式,环境大气是散热的最终热阱。冷却塔的传热传质动态响应将影响冷凝器入口冷却水水温,进而对核电站的效率及安全造成影响。目前对冷却塔的分析计算基本针对稳态工况,通过分析其结构与设计性能的关系来优化设计,用于运行特性分析的实时动态仿真计算研究未见报道。对冷却塔的瞬态进行仿真模拟,可研究内陆核电站事故工况下的安全性,因此其具有重大的工程与理论意义。本文以自然循环逆流湿式冷却塔为研究对象,通过详细分析冷却塔内传热传质和流动过程,研究建立了描述冷却塔内空气和循环水流动的动态数学物理模型,以及以Merkel模型为基础的气、水间传热传质模型。假设气流场为二维轴对称不可压缩流动,采用有限体积法及SIMPLE算法来求解二维的Navier-Stonkes方程,假设水流场为一维流动,采用经典的四阶Runge-Kutta法求解一维的常微分方程。采用Fortran语言完成仿真程序的编写及调试,并以某600MW电站的实际运行参数进行计算,将出塔水温的计算值与实测值做了对比,验证模型和程序的正确性。在此基础上,选取某气象条件,分别针对淋水密度均匀分布及淋水密度沿径向成线性分布的不同工况,对空气场的速度、温度以及含湿量的分布进行了分析,并对水流场的水温分布以及各特征面上的水温分布进行了分析,之后,分别考察了进塔水温、进塔水流量、进塔空气相对湿度、进塔气温这些参数的变化对出塔水温的影响,最后计算了电站在变负荷或事故工况下,循环水入口温度和流量发生改变时,冷却塔出口气温和水温的瞬态响应曲线,为内陆核电站冷却塔的设计和运行提供了进一步的依据。
[Abstract]:Different from the open circulation mode used in the circulating cooling system of the coastal nuclear power station, the circulating cooling system of the inland nuclear power station basically adopts the closed cycle cooling mode of the cooling tower. The ambient atmosphere is the final heat trap for heat dissipation. The dynamic response of heat and mass transfer of cooling tower will affect the temperature of cooling water at the inlet of condenser, and then affect the efficiency and safety of nuclear power station. At present, the analysis and calculation of cooling tower is basically aimed at the steady state condition. By analyzing the relationship between the structure and the design performance to optimize the design, the study of real-time dynamic simulation for the operation characteristic analysis has not been reported. The transient simulation of the cooling tower can be used to study the safety of the inland nuclear power plant under the accident condition. Therefore, it is of great engineering and theoretical significance. In this paper, the natural circulation countercurrent wet cooling tower is taken as the research object, and the heat and mass transfer and flow process in the cooling tower are analyzed in detail. A dynamic mathematical and physical model describing the flow of air and circulating water in a cooling tower and a model of heat and mass transfer between gas and water based on Merkel model are established. It is assumed that the flow field is two dimensional axisymmetric incompressible flow. The finite volume method and SIMPLE algorithm are used to solve the two-dimensional Navier-Stonkes equation. The water flow field is assumed to be a one-dimensional flow. The classical four-order Runge-Kutta method is used to solve the one-dimensional ordinary differential equation. The Fortran language is used to complete the programming and debugging of the simulation program. The actual operation parameters of a 600MW power station are calculated, and the calculated values of the water temperature of the outlet tower are compared with the measured values to verify the correctness of the model and the program. On this basis, a certain meteorological condition is selected. The velocity, temperature and moisture content distribution of air field are analyzed under different conditions of uniform distribution of water density and linear distribution of water density along radial direction. The water temperature distribution of the water flow field and the water temperature distribution on each characteristic surface are analyzed. After that, the effects of the water temperature of the inlet tower, the flow rate of the inlet tower, the relative humidity of the air in the inlet tower and the temperature of the inlet tower on the water temperature of the outlet tower are investigated respectively. Finally, the transient response curves of air temperature and water temperature at the outlet of cooling tower are calculated when the inlet temperature and flow rate of circulating water change under the condition of variable load or accident, which provides a further basis for the design and operation of cooling tower in inland nuclear power station.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM623

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