蒸汽空气混合物与过冷水直接接触凝结研究

Research on Direct Contact Condensation of Steam-air Mixture in Subcooled Water

通过实验研究了矩形通道内蒸汽-空气混合气体与过冷水的直接接触凝结过程。通过可视化窗口,利用高速摄像机发现了蒸汽质量流率150~400 kg/(m^2s),水质量流率6000~8000 kg/(m^2s),水温30℃条件下的三种纯蒸汽凝结流型:泡状流、振荡射流和稳定射流。研究了空气质量分数对凝结流型、壁面温度分布和压力分布的影响,结果表明:随着空气含量的增加,蒸汽在汽液相界面上的凝结变得困难,泡状流和振荡射流的汽液相界面明显变长,稳定射流则变化不大,汽液混合层的厚度明显增加,蒸汽区尾部聚集大量的气泡。此外,随着空气含量的增加,上壁面的温度降低,压力升高,下壁面的温度和压力均升高,且压力峰值点远离蒸汽喷嘴出口,说明汽液相界面变长。

An experimental research was conducted on direct contact condensation of steam-air mixture in subcooled water flow in a rectangular channel.The inlet parameters including steam mass flux,water mass flux and water temperature were tested respectively in the range of 150~400kg/（m^2s）,6000~8000 kg/（m^2s） and 30℃.Three different flow patterns for pure steam jet in water flow were observed as bubble flow,oscillation jet and stable jet by using a high speed camera through the visualization window.The effect of air mass fraction on flow patterns,wall temperature and pressure distributions was discussed,the results indicated that：with the increase of air mass fraction,the condensation of steam on the interface was hindered,the interface size of bubble flow and oscillation jet enlarged while that of stable jet changed a little,the mixture layer thickened and large amount of gas bubbles gathered at the steam region tail.Moreover,as air mass fraction increased,the upper wall temperatures decreased while the bottom wall temperatures and pressures increased.The peak of bottom wall pressure distributions moved away from the steam nozzle outlet,indicating that the interface size enlarged.