凝汽器壳侧换热特性影响因素研究

Study of the heat transfer effects in the shell side of condensers

影响电站凝汽器换热的因素有多种,研究这些影响因素有利于提高凝汽器换热性能。建立凝汽器壳侧流体流动与换热带有多孔介质概念的准三维数值模型,使用数值模型模拟实验凝汽器内部换热特性。在实验中,考虑冷却水入口质量流量、入口温度、蒸汽负荷、漏空气量对换热特性的影响;同样研究了湍流黏度、网格数对计算结果的影响。凝汽器入口参数直接影响凝汽器换热特性,漏空气量增大传热热阻,增大传热端差,降低传热系数;湍流黏度取值不同对数值结果有一定的影响;网格数对凝汽器实时仿真影响很大。

There are some factors influencing the heat transfer in the shell side of power plant condensers. It is very important to study the factors for improving condensers’heat transfer characteristics. A quasi-three-dimensional method with porous medium was developed to simulate the flow field and heat transfer in the shell side of condensers, then the model was used to simulate internal heat transfer characteristics of condenser by experiment. The inlet cooling water mass flow and temperature, inlet steam mass flow, and inlet air mass fraction were considered influencing the heat transfer. The turbulent viscosity and grids number were also taken into account for the numerical results. Inlet parameters can directly influence the heat transfer. Inlet air mass fraction increases the heat transfer resistance and the temperature difference, decreases the heat transfer coefficient. Different selection of the value of turbulent viscosity will lead to different numerical results. The number of grids has great influence on the real-time simulation.