Heat Transfer Characteristics and transition Mode in condensation Curves

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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.