【作者】 张来；

【导师】 杨勇平； 杜小泽；

【作者基本信息】 华北电力大学（北京） ， 热能工程， 2006， 硕士

【摘要】 针对电站直接空冷系统的基本换热元件矩形翅片椭圆管和管束,建立三维物理数学模型,对空气侧流动和传热性能进行数值研究。分析了翅片上无扰流孔和开有扰流孔两种情况下矩形翅片表面的局部表面传热系数分布规律,发现椭圆基管后存在的尾流区使得翅片的强化换热作用减弱。对影响空气侧传热和流动性能的因素,包括风速、翅片间距、翅片厚度、扰流孔的相关参数进行了综合优化分析。根据电站空冷系统的实际结构,在风向与管束长度方向呈60度夹角的情况下对矩形翅片椭圆管束进行了热态模拟,并与实验结果进行了对比分析。对不同翅片间距的两排管管束流动和传热性能进行了分析,得到翅片间距变化对空气侧表面传热系数和流动阻力的不同作用规律。本文的工作有助于进一步揭示大型直接空冷系统相关影响因素的作用机制,对提高机组的优化运行水平和经济性具有参考价值。更多还原

【Abstract】 The numerical analysis were performed for the air-side flow and heat transfercharacteristics of rectangular-fin elliptic-tube and tube bundle, which are thefundamental element used in direct air-cooled power plant by applying the 3D physics-mathematics models. The local heat transfer coefficients distributions on the surface offins with and without interrupted holes were discussed. The results indicated that thewake region behind the tube weaken the heat transfer of tube fin. The influencingparameters include that of air velocity, fin spacing, fin thickness and geometricalparameters of the interrupted holes, which affect the airside flow and heat transferperformance, are optimized with system analysis. The heat transfer characteristics oftube bundles with the 60° inclination, according to the configuration of practicalair-cooled system, were simulated, and compared with the experimental data. The flowand heat transfer performances of two-row bundles with different fin spacing are carriedout. The effects of fin spacing on air-side heat transfer coefficient and flow resistance arediscussed. The present works can benefit to the comprehensive understanding to thedirect air-cooled technology.更多还原