在带有温度梯度的凝结表面上进行了一系列质量分数酒精蒸气的Marangoni凝结试验,研究了酒精蒸气的传热系数.结果表明:与日本学者Utaka的试验数据相比,质量分数为99%的水和1%酒精混合蒸气在同样试验条件下(p=84.5 kPa、v=2 m/s)的传热系数提高了15%;在相似的试验条件下,带温度梯度试验块其传热系数的提升是由于液膜内部存在两种相反的运动,这两种相反运动扰乱了凝结液膜,从而减小了液膜的热阻;对传热系数随过冷度变化的规律进行了定性分析.
Experimental tests were performed on Marangoni condensation heat transfer of ethanol-water mixtures with different concentrations on a surface with temperature gradient.Results indicate that for the mixture with a mass concentration of 1% ethanol and 99% water,the heat transfer coefficient can be raised by 15%,under same experimental conditions(p=84.5 kPa,v=2 m/s),compared with that of Utaka experiment.Under similar experimental conditions,the improvement of heat transfer coefficient of test block with temperature gradient is found to be caused by existence of two reverse motions in the condensation film,which disturbs the condensation film and hence reduces its heat resistance.Moreover,qualitative analysis is also carried out to study how the heat transfer coefficient varies with the degree of supercooling.