Condensation Heat Transfer from Humid Air to a Horizontal tube

从潮湿空气到水平管的冷凝传热

基本信息

批准号：
60550158
负责人：
NAGATA Takashi
金额：
$ 0.96万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550158/
关键词：
Humid Air Condensation Heat Transfer A Horizontal Tube Laminar Film Condensation Numerical Analysis Similarity Solution Samll Temperature Difference Type Heat Exchanger

项目摘要

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,

本项目涉及从潮湿空气到水平管的传热传质的实验研究以及在平板上流动的潮湿空气中水蒸气层膜冷凝的数值分析。本研究旨在建立一种对湿空气进行冷却除湿的小温差型换热器的设计方法。实验和数值分析得到的主要结果总结如下：(1)冷却试验中的膜状、滴状、混合状等冷凝形态很大程度上取决于试管表面状况，但由于量小，对传热影响不大。（2）图中传质的舍伍德数和对流传热的努塞尔数是雷诺数的函数。（3）从蒸气-空气边界层的温度和质量浓度分布分析混合物，从热力学角度看，界面附近存在超饱和状态，但实际上会因雾的形成而趋于饱和状态。(4)发现界面与壁面的温差很小，凝结对对流的影响很小。 (5) 从相似解中获得传热和传质的无量纲相关性，然后将它们结合起来估计总传热，