Study on Flow and Heat Transfer Characteristics of Boiling/Bubbling System with Falling Liquid Film

本文以R-113制冷剂的蒸气和液体模拟高温高压下的蒸汽和水，研究了在垂直管中向液柱注入气体和从管顶向液柱以降膜形式供给液体的情况下的逆流弹状流特性。垂直布置的测试管是直径为14.8 mm、长度为1.5 m的Pyrex玻璃管。供给到测试管顶部的R-113液体以降膜的形式向下流动到恒定塌陷水平的液柱。将R-113蒸汽注入试验管底部的液柱中，当气体注入液柱中时，无论有无降膜，均发生两相混合物液面膨胀并伴有周期性波动。当两相混合物中的流动状态为段塞型时，两相混合物液面的平均高度以及波动幅度随着蒸汽流量的增加而变高。当流动状态转变为环状时，随着蒸汽流量的增加，膨胀高度急剧增加。随着降膜流量的增大，混合物液面的平均高度和液面波动幅度增大。这些结果与我们以前在空气和水中进行的类似实验中获得的结果一致。然而，在本实验中获得的波动幅度的值比在空气-水实验中获得的波动幅度的值小约50%。对两相混合物液面的平均高度和液面波动幅度进行了物理分析。分析结果与实验结果吻合较好。

This study examines the characteristics of the countercurrent slug-flow in the case where gas is injected into a liquid column in a vertical pipe and liquid is supplied to the liquid column in the form of the falling film from the top of the pipe.In the experiments, vapor and liquid of refrigerant R-113 is used to simulate steam and water at high pressure and high temperature. The test pipe arranged vertically is a Pyrex glass pipe of 14.8 mm in diameter and 1.5 m in length. R-113 liquid supplied to the top of the test pipe flows down in the form of the falling film to the liquid column of the constant collapsed level. R-113 vapor is injected into the liquid column at the bottom of the test pipe.When gas is injected into the liquid column, two-phase mixture level swell takes place accompanying periodical fluctuation in both cases with and without the falling film. When a flow state in the two-phase mixture is a slug type, the mean height of the two-phase mixture level and also the fluctuation amplitude become higher with an increase of the vapor flow rate. When the flow state turns into an annular type with an increase of the vapor flow rate, the swell height increases sharply. The mean height of the mixture level and the level fluctuation amplitude increase as the flow rate of the falling film is increased. These results are consistent with what were obtained in similar experiments for air and water performed previously by us. However, the values of fluctuation amplitude obtained in the present experiments are approximately 50 % smaller than those in the air-water experiments. The mean height of the twophase mixture level and the level fluctuation amplitude are physically analyzed. The analyzed results agree with the experimental results satisfactorily.