摘要：

对自由降落液柱流在低压条件下的绝热蒸发过程进行了研究，建立了低压液柱气液界面蒸发模型，结合液柱自由降落绝热蒸发实验(温度20～55℃、蒸发压力2～15 kPa、Reynolds数1500～5000)，得到了本研究体系蒸发传热准数方程。研究发现，过高的过热度（ΔT_sup>11℃）易产生雾沫夹带而降低气液分离效率，液柱长径比在43.5～87范围内可使蒸发效率达到63.2%

Abstract:

The process of adiabatic evaporation in a free falling liquid column was investigated theoretically and experimentally.A model for the vacuum evaporation on the surface of vapor-liquid flow was built with an adiabatic evaporation experiment at temperature of 20—55℃, evaporation pressure of 2—15 kPa, and Reynolds number 1500—5000.A criterion equation for the heat transfer in the system was obtained.The analysis result showed that excessive superheat (ΔT_sup>11℃)would cause entrainment to decrease the separation efficiency.The evaporation efficiency could reach 63.2%—6.5% with the length-diameter ratio from 43.5 to 87.Higher length-diameter ratio caused a breakup of the liquid column, and the enhancement of the evaporation efficiency was not significant.Based on the evaporation model, the evaporation process of free falling liquid column could be analyzed effectively with process simulation, which provides a reference for its industrial design.