不同管径毛细管的毛细蒸发特性实验

Capillary evaporation in tubes with different diameters

以无水乙醇为工质,采用3种不同管径的圆形毛细管进行毛细蒸发实验。研究结果表明:毛细管毛细蒸发过程中,蒸发界面移动后会延展形成一层液膜,这层液膜可以大幅提高液体蒸发速率。这是因为液膜蒸发引起的温度变化会通过Marangoni效应转化为表面张力差,使液膜在蒸发的同时得到不断补充,形成高效的蒸发-补充机制。随管径增大,液膜厚度增加,蒸发稳定性变好,速率变化幅度减小。工质整体蒸发速率随管径变大呈递减趋势。

The experiment was conducted to investigate the characteristic of capillary evaporation in capillary tubes with three different diameters using alcohol as working fluid.The results indicated that the evaporating interface with extend and form a thin liquid film during the evaporation,which can rapidly increase the evaporating rate.The temperature caused by the liquid film evaporation will change into the difference of surface tension because of the Marangoni effect,the liquid film will be supplemented while evaporating and form the high-effective“evaporation-supplement”mechanism.With the increase of the diameter,the liquid film become thicker and the stability is improved,the change rate of the interface moving rate decreased.Meanwhile,the overall evaporation rate decreases with the increasing of tube diameter.