水平螺旋槽管壁面液膜传热特性的研究

A Study on Enhanced Heat Transfer of Liquid Film Outside a Horizontal Spirally Fluted Tube

对管式高效传热传质元件的工程应用进行理论探讨 ,根据水平螺旋槽管壁面液膜的形成机理及传热特性 ,通过建立单组分流体的物理和数学模型 ,得到了液膜速度和厚度解析解 ,并分析了在蒸发、冷凝时水平螺旋槽管的表面几何形状对液膜厚度分布的影响。结果表明 :液膜的厚度主要受表面张力和槽道表面几何形状的影响 ,在槽道内弯处较厚 ,而在槽道起始处较薄 ,冷凝时与蒸发时相比液膜厚度更薄 ,液膜分布更均匀。相对于光滑直管 ,水平螺旋槽管壁面液膜具有更均匀的厚度分布 ,具有更好的传热传质性能。

In this work, a theoretical study of the formation of falling liquid film on the surface of a horizontal spirally fluted tube is presented. The mathematical model for pure fluid is established based on some physical simplifications. Analytical solutions of velocity distribution and liquid film thickness are obtained in the case of evaporation or condensation. The effects of the surface geometry of the spirally fluted tube on the formation of the liquid film are investigated. The results show that the formation of liquid film is mainly affected by the surface tension of the liquid and the surface geometry of the spirally fluted tube. The distribution pattern of the liquid film thickness is thicker at the bottom of the trough and thinner at the upper crest. Also, it is thinner and more homogeneous in the case of condensation than evaporation. Consequently, there is a significant improvement in heat transfer, compared with the classical smooth tube, where the film thickness is of an unbounded fashion.