布液方式对水平蒸发管管间流型转换的影响

为了探究液体分布装置布液方式对水平管管间液体流动流型转换的影响规律,采用可视化方法对3种工质、两种布液高度、8种液体分布装置开孔规格下的水平管管间液体流动流型转换进行了实验测量.通过高速摄像机拍摄,得到了流量由大到小(76～4.5L·h-1)调节时管间液体流动的5种流动形态和4种流动流型转换;对比膜雷诺数和伽利略数显示,测量结果与文献数据符合很好,转换雷诺数的最大偏差小于15%.实验结果表明:孔径不变,转换雷诺数随着孔间距增大而增大,孔间距不变,转换雷诺数随着开孔孔径增大而减小;直接布液方式的转换边界大于间接布液方式的转换边界.随着无量纲特征参数的逐渐增大,两种布液高度下的转换边界的差异逐渐减小.当无量纲特征参数大于40时,布液高度对管间液体的流动流型转换几乎无影响.

Effects of Liquid Distribution Method on Falling-Film Mode Transitions Between Horizontal Tubes

The inter-tube flow mode transitions of three working fluids under the conditions of two distribution heights,eight different orifice configurations were measured with the visualization method,and the effect of liquid distribution on falling-film flow transitions was discussed.Five flow modes and four flow transitions were obtained by a high-speed camera.The measurement results agree well with literature data from reduced film Reynolds number and non-dimensional Galileo number,and the maximum relative deviation of transition Reynolds number is less than 15%.The experiment results show that the orifice configuration has a significant influence on inter-tube flow mode transition.The transition Reynolds number decreases with an increase in the hole diameter at a fixed adjacent hole distance while it increases with an increase in adjacent hole distance at a fixed hole diameter.The direct distribution causes larger transition boundary than the indirect one,and the difference between the transition boundaries under direct distribution and indirect distribution decreases with the increase in the non-dimensional characteristic parameter.The influence of the distribution height on flow mode transitions may be ignored when the non-dimensional characteristic parameter is greater than 40.