水蒸气在垂直钛板表面的冷凝传热特性

Condensation Heat Transfer Characteristic of Steam on Vertical Titanium Plate

对水蒸气在垂直钛板表面的冷凝传热特性进行了可视化实验研究。实验结果表明,蒸汽在钛表面为液滴和沟流状液膜共存的混合冷凝形式。随着表面过冷度的增大,滴状区所占的面积比η逐渐减小,且液滴的脱落直径逐渐增大,导致表面的冷凝传热系数随之下降。η值大于50%时,冷凝传热系数随滴状区所占面积比的减小而陡降,滴状区面积小于膜状区后,η值对冷凝表面传热性能的影响较小。

Condensation heat transfer characteristics of steam on vertical titanium plates were investigated experimentally. Dropwise and rivulet filmwise co-existing condensation mode of steam was observed on titanium surface. With the increasing of surface subcooling, the ratio of area covered by drops （η） decreases and departure diameters of droplets increase, resulting in decreasing of condensation heat transfer coeffient. Condensation heat transfer coements decrease sharply with the values of η decreasing when the fraction of the surface area covered by drops is greater than that covered by rivulets, inversely the values of η have little effect on the heat transfer properties.