Heat Transfer Characteristics and transition Mode in condensation Curves

采用一种特殊设计的冷凝块，在冷凝液流动方向上具有较大的长度，对冷凝面上游冷凝液流动的影响进行了实验研究。传热块由六个热独立的铜块组成，用于测量局部传热量，并消除了传热面边缘的影响。两种有机蒸气，即：e.丙二醇和乙二醇蒸汽以及吸附在冷凝表面上的十八烷基乙醇分别用作测试蒸汽和实现疏液表面的促进剂。计算结果给出了局部热流密度和换热系数的分布、凝结方向以及上游来流凝结水所覆盖的表面积。进一步阐明了在过渡区形成的凝结水沟的数密度以及最大热流密度和最大热流密度点处凝结水覆盖的表面分数对凝结水流动方向的依赖关系，并采用了由凝结水滴直径归一化的无量纲距离.

An experiment was carried out on the effect of condensate flow from upstream of the condensing surface by using a specially devised condensing block which had relatively large length in the direction of condensate flow. The heat transfer block was composed of thermally independent six copper sub-blocks to measure the local values of heat transfer, and was built to remove the effect of the edge of heat transfer surface. Two kinds of organic vapors, i. e. propylene glycol and ethylene glycol vapors, and octadecanethiol adsorbed on the condensing surface were used as a test vapor and a promoter realizing the lyophobic surface, respectively. The results of the distributions of local heat flux and heat transfer coefficient, the aspect of condensation and the surface fractions covered by condensate flowing from upstream were shown. Further, it was clarified that the number density of the rivulets of depdrting condensate formed in the transition region and the dependencies of maximum heat flux and the surface fraction covered bydeparting condensate at the maximum heat flux point on the direction of condensate flow were determined systematically by using non-dimensional distance normalized by the departing drop diameter.