螺旋扁管管外蒸汽冷凝双侧强化传热试验研究

Experimental research on double side enhanced heat transfer of water vapor condensation on spiral elliptical flat tube

为促进螺旋扁管在冷凝换热装置上的应用,对螺旋椭圆管管外蒸汽冷凝工况下的传热特性进行了试验研究。研究结果表明,螺旋椭圆管在强化管内无相变对流传热的同时也可以强化管外冷凝传热。相同工况下,同圆管相比,所用螺旋椭圆扁管的总传热系数高11%-16%,管内传热系数高约18%,管外冷凝传热系数高约9%。并从二次流减薄传热边界层及冷凝表面利于排除冷凝液的角度,分析了螺旋椭圆扁管的双侧强化传热机理。

In order to promote the application of spiral elliptical flat tube in heat exchangers,an experimental research was carried out on the double side enhanced heat transfer properties of spiral elliptical flat tube under water vapor condensation outside the tube.The results show that not only the convective heat transfer inside tube but also the condensation heat transfer outside tube can be enhanced.Under the same condition,compared with the smooth tube,the overall heat transfer coefficient of spiral elliptical tube is 11%-16% higher,the tube side heat transfer coefficient is about 18% higher,and the condensation heat transfer coefficient outside tube is about 9% higher.The secondary flow in tube can reduce the thickness of heat transfer boundary layer and the condensate can be easily drained from the condensation surface is the main reason of double side heat transfer enhancement.