水平蛋形管降膜蒸发器管外液膜铺展数值模拟  

Numerical simulation of film spreading on horizontal oval-shaped tube falling film evaporator

作　　者：沈永泽 李庆生[1] SHEN Yong-ze;LI Qing-sheng(School of Mechanical and Power Engineering,Nanjing Tech University,Nanjing 211816,Jiangsu Province,China)

机构地区：[1]南京工业大学机械与动力工程学院,江苏南京211816

出　　处：《化学工程》2021年第1期70-75,共6页Chemical Engineering(China)

基　　金：江苏省六大人才高峰资助项目(2014-ZBZZ-013)。

摘　　要：水平异形管与圆管相比,具有管外液膜成膜排数多、液膜流动稳定和传热性能好等优点。对柱状流下水平管降膜蒸发器管外液膜流动进行三维数值模拟,分析椭圆率、喷淋高度和横截面尺寸对蛋形管管外液膜铺展的影响。结果表明:蛋形管管外液膜铺展分为喷淋区、平稳区、叠加区与脱落区。液膜厚度随轴向位移Z增大而增大;当Z=0—6 mm时,液膜厚度随椭圆率变大出现先下降后上升趋势;当Z=8—10 mm时,液膜厚度随椭圆率变大而减薄,波动幅度最大值为26.13%。喷淋高度对液膜厚度影响较小,波动幅度最大值为10.53%。当Z=0,4,6 mm时,液膜厚度随横截面尺寸变大而增厚;当Z=10 mm时,随周向比例系数增大,液膜厚度随横截面尺寸变大出现先上升后下降趋势。Compared with the horizontal circular tube,horizontal oval-shaped tube has many advantages of more film-forming rows outside the tube,stable liquid film flow and good heat transfer performance.The three-dimensional numerical simulation of the liquid film flow outside the horizontal tube falling film evaporator was carried out under the cylindrical flow.The effects of the ellipticity,the liquid distribution height and the cross-section size on the liquid film spreading outside the oval-shaped tube were analyzed.The results show that the spreading of liquid film outside the oval-shaped tube is divided into spray zone,stationary zone,superposition zone and shedding zone.The film thickness increases with the axial displacement Z increasing.There is a tendency that the film thickness decreases firstly and then increases with the increase of the ellipticity at Z=0-6 mm.When Z=8-10 mm,the film thickness decreases with the ellipticity increasing,and the maximum value of fluctuation range is 26.13%.The liquid distribution height has little effect on the film thickness,and the maximum value of fluctuation range is 10.53%.When Z=0,4,6 mm,the film thickness increases with the cross-section size increasing.With the circumferential scale factor increasing,the film thickness first increases and then decreases as the cross-section size increases at Z=10 mm.

关 键 词：柱状流 异形管 液膜厚度 水平管降膜蒸发器 

分 类 号：TK124[动力工程及工程热物理—工程热物理]