水平管降膜蒸发器管外液膜铺展数值分析

运用FLUENT软件对水平管降膜蒸发器管外液膜的铺展过程进行数值模拟,分析了流量、管间距、管径及流体温度对水平管外液膜铺展的影响。模拟研究结果表明,液膜在水平管外分布不均匀,液膜铺展呈现波峰-平稳-波峰的周期性规律。在整个铺展区域内液膜厚度随流体体积流量的增大而增大,随流体温度的增大而减小;在叠加区内液膜厚度随着管间距的增大而增大;在平稳区域和冲击区域内液膜厚度随着管间距的增大而减小。周向角θ为45°时,液膜厚度在叠加区随管径的增大而增大;周向角θ为90°、135°时,液膜厚度在整个铺展区域内随管间距的增大而减小。

Numerical Analysis of Liquid Film Spreading Outside of Horizontal Heat Exchange Tube of Falling Film Evaporator

The FLUENT software was applied to simulate the spreading process of liquid film outside the horizontal tube of the falling film evaporator. The influences of flow rate, tube spacing, tube diameter and fluid temperature on the liquid film spreading outside the horizontal tube were analyzed. The results show that the liquid film is unevenly distributed outside the horizontal tube and the spreading of liquid film exhibits the periodicity of peak-stationary-peak. In the entire spreading area, the thickness of the liquid film increases with the increase of the flow rate, decreases with the increase of the fluid temperature. The thickness of the liquid film in the superimposed zone increases with the increase of the tube spacing, while the thickness of the liquid film in the plateau and the impact zone decreases with the increase of the tube spacing. When the circumferential angle θ=45°, the thickness of the liquid film increases with the increase of the pipe diameter in the superposition zone. When the circumferential angle θ=90°,135°, the liquid film thickness decreases with the increase of the tube spacing throughout the spreading area.