Condensation Heat Transfer from Humid Air to a Horizontal tube

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The present project deals with both the experimental study of heat and mass transfer from humid air to a horizontal tube and numerical analysis of laminar film condensation of water vapor in humid air flowing on a flat plate. The study aims at the establishment of the design method of a small temperature difference type heat exchanger in which humid air is cooled and dehumidified. Main results obtained in experiments and numerical analysis are summerized as follows:(1) Condensation pattern such as film, drop and mixed wise in the cooling test much depends on surface condition of test tube, however, little effect on heat transfer due to small amount of vapor content.(2) Sherwood number for mass transfer and Nusselt number for convective heat transfer are shown as function of Reynolds number in the figure.(3) From the analysis of temperature and mass concentration distributions in the boundary layer of vapor -air mixtures, there exists thermodynamically a supper saturated state near the interface, but it actually will tend to a saturation state by formation of fog.(4) It became clear that temperature difference between the interface and the wall is so small and little ffect of condensation on convective heat trasfer is recognized.(5) Nondimentional correlations on heat and mass transfer are obtained from similarity solutions, then total heat transfer is to be estimated by combining them,