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

本研究考察了在垂直管道中将气体注入液体柱，液体以从管道顶部降膜的形式供应给液体柱的情况下，逆流段塞流的特性。实验采用制冷剂R-113的蒸汽和液体模拟高压高温下的蒸汽和水。垂直布置的试验管为直径14.8 mm、长1.5 m的耐热玻璃管。供至试验管道顶部的R-113液体以降膜形式向下流动至定塌位液柱。将R-113蒸汽注入到测试管道底部的液柱中。当气体注入液柱时，在有无降膜的情况下均发生两相混合液面膨胀，并伴有周期性波动。当两相混合物中某一流动状态为段塞型时，随着蒸汽流量的增加，两相混合物液位的平均高度和波动幅度都增大。随着蒸汽流量的增加，流态变为环空型时，膨胀高度急剧增加。随着降膜流量的增大，混合液面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的类似实验中得到的结果是一致的。然而，本实验得到的波动幅度值比空气-水实验的波动幅度值小约50%。对两相混合液面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.