层流波动区膜状凝结雷诺数关系式对传热计算的影响

Effect of Reynolds Correlation of Film Condensation in Laminar and Wavy Flow on Heat Transfer Calculation

在核电站安全壳和稳压器中存在膜状凝结现象。液膜的雷诺数关系式是膜状凝结传热计算的基础,有分别基于质量和能量的两种关系式形式,前人工作中未具体研究这两种关系式的差别。针对管外纯蒸汽自然对流膜状冷凝传热,本文通过求解液膜传热关系式和不同雷诺数关系式组成的联立方程,分别得到在光滑的和有波动的液膜层流区基于质量和能量关系的雷诺数表达式。分析表明:在光滑液膜层流区域,基于质量和能量关系得到的雷诺数具有等价性,计算得到的传热系数相等;在有波动液膜层流区域,基于质量关系得到的雷诺数Re_(mass)较能量关系得到的雷诺数Re_(energy)偏小,且计算得到的平均传热系数最大偏差可达30.3%。通过与实验数据比较,验证了基于Re_(energy)计算得到的平均传热系数在层流波动区域更加准确。

The film condensation widely exists in the compact containment and the pressurizer of nuclear power plant. The Reynolds correlation in film condensation is the foundation of calculating heat transfer coefficient, and few studies focus on the difference between two Reynolds correlations based on mass and energy respectively. For outer tube natural convection film condensation of pure steam, by solving a set of simultaneous equations of the correlations of film condensation and different Reynolds correlations, the expressions of Reynolds number based on mass and energy in laminar and wave-free flow and in laminar and wavy flow were obtained, respectively. It is indicated that in laminar and wave-free flow, the definitions of Reynolds number based on mass Re and that based on energy Reenergy are equivalent, and the heat transfer coefficients are the same. Whereas in laminar and wavy flow, Re is smaller than Reenergy, and the maximum deviation of the average heat transfer coefficients based on these two definitions of Reynolds number is about 30.3%. Compared with experiment data, it is proven that the result based on Reenergy is more accurate in laminar and wavy flow.