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中文摘要：
在不同蒸气压力,相同蒸气流速条件下,完成了不同酒精浓度的混合蒸气在不同管径的竖直管外凝结换热实验。凝结换热特性曲线显示了相似的特性：随着酒精浓度的增加,凝结传热系数显著下降;随着表面过冷度的增加,凝结传热系数显示出有峰值的非线性特点。在相同条件下,半径为5mm管外的凝结传热系数峰值出现在较大过冷度范围内,且峰值高于在半径为10mm管外的凝结传热系数峰值。当蒸气压力为84.52kPa,流速为2m.s-1时,酒精浓度为1%的混合蒸气在半径为5mm竖直管外凝结传热系数最高达150kW.m^-2.K^-1,约为水蒸气的8倍。此外,根据记录的凝结形态,珠状凝结出现在很广的浓度以及过冷度范围内。
英文摘要：
The condensation heat transfer of the water-ethanol vapor mixture on vertical tubes with different radii was studied experimentally at the same vapor velocity and different vapor pressures.A wide range of ethanol concentration was used.The results indicated that the condensation heat transfer of water-ethanol vapor mixture on vertical tubes was extremely intensified in the low ethanol concentration range.The maximum heat transfer coefficient was 150 kW·m-2·K-1 at p=84.52 kPa,U=2 m·s-1,C=1%,on the tube with 5 mm radius,which was around 8 times of that of pure water vapor.With the increase of ethanol concentration,the condensation heat transfer coefficient decreased notably.Moreover,with the increase of vapor-to-surface temperature difference,the condensation curves of heat flux and heat transfer coefficient revealed nonlinear characteristics and had peak values.The nonlinear condensation characteristic curves were caused by the complex changes in condensation mode and the diffusion resistance inherent as vapor-side thermal resistance in the condensation of the binary vapor mixtures.The condensation heat transfer characteristics were also different when different tube radii were adopted.Under the same conditions,the maximum heat transfer coefficient of the vapor mixture on the vertical tube with 5 mm radius was at a higher degree of super-cooling of surface compared with that of the tube with 10 mm radius,and the value was higher than that of the tube with 10 mm radius.In addition,according to the condensation modes recorded,dropwise condensation occurred over a wide range of ethanol concentration and vapor-to-surface temperature difference.
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