水平管蒸发器管外降膜流动数值分析

Numerical Analysis of Falling Film Flow outside the Tube of Horizontal Tube Evaporator

利用VOF模型研究水平管蒸发器管外气液两相的降膜流动,分析了喷淋密度、换热管外径及水温对管外液膜厚度分布的影响。模拟计算结果表明,周向角度为90°～170°时,液膜厚度分布更加均匀,且液膜厚度随着喷淋密度的增大而增加;换热管外径在?19～?51mm时,随着管外径的增大,液膜平均厚度显著减小,但换热管外径继续增大时,膜厚减小的幅度趋于平缓;随着水温的升高,管外液体流动加快,导致液膜厚度减小。

The VOF model was used to study a gas liquid two phase falling film flow outside the tube of horizontal tube evaporator. The distribution characteristics of liquid film thickness were investigated at different spray density, heat exchange tube external diameter and feed tempera ture. The results show that the film thickness increases with the growth of spray density and the thickness distribution of liquid film is more uniform when the circumferential angle is 90°-170°. When external diameter of heat exchange tube is within the scope of Ф19-Ф51 mm, the average thickness of liquid film significantly decreases with the increase of external diameter. But the film thickness decreases gradually when the external diameter continues to increase. With the increase of feed temperature, the liquid film thickness decreases due to the accelerated liquid flow outside the tube.