竖直通道内下降液膜蒸发换热的数值研究

Computational Study of Falling Film Evaporation in Vertical Channel

下降液膜蒸发换热是CAP1400型反应堆非能动安全壳采用的重要换热机理,准确计算下降液膜蒸发换热量对非能动安全壳换热性能的评价有至关重要的影响。本文利用ANSYS FLUENT软件二次开发,实现了两种下降液膜蒸发换热模型的构建,并将两种模型计算结果与实验结果进行了对比分析。计算结果表明:两种模型均可较为准确地计算壁面下降液膜的蒸发换热系数;模型1的计算结果更加可靠,但在靠近壁面处需非常精细的网格;模型2在壁面处可使用较粗网格,但计算结果对对流换热系数的依赖较大。

Falling film evaporation plays a key role in the heat removal process of the containment of the CAP1400.In order to estimate the heat removal capability of the containment,it is important to calculate the evaporation rate accurately.In the paper,two different evaporation models were built to simulate film evaporation in a vertical channel based on ANSYS FLUENT code.The prediction results by two evaporation models and experimental data were compared.The results show that both models can predict the evaporation heat transfer coefficient accurately.The results calculated by the model 1are more reliable with finer mesh.The model 2can be used with coarser mesh near the wall.However,the model depends greatly on the calculation of the convective heat transfer coefficient.