三相线钉扎的大液滴蒸发实验

利用实践十号返回式科学实验卫星蒸发对流箱,开展了三相线处于钉扎状态且接触半径大于毛细长度的无水乙醇大滴在加热PTFE表面蒸发的地基科学实验.实验发现,液滴体积随时间线性递减,但钉扎大液滴蒸发过程中没有出现恒定接触角(CCA)阶段.与小液滴蒸发的恒定接触半径(CCR)阶段相同,大液滴的平均蒸发速率也与初始体积无关,表明受...

Experimental Investigation of Large Sessile Droplet Evaporation with Pinned Triple Line

The in-depth study on the evaporation of large sessile liquid droplets has important scientific significance and engineering application value. Using the evaporation-convection box in SJ-10 scientific experimental satellite, the scientific matching experiments of large sessile ethanol droplets evaporation on heated PTFE are conducted on the ground, in which the triple line of the liquid droplet is pinned and the contact radius is greater than capillary length. In present experiments, it is found that the volume of the large sessile droplet with pinned triple decreases linearly with time, but the CCA mode during evaporation is not observed. The average evaporation rate is also focused on, and it is found to be independent on initial volume of the large sessile pinned droplet with the same contact radius, which is similar in the tendency for small evaporating liquid drop, indicating that evaporation occurs most violently near the triple line. The instant evaporation rate is observed to increase firstly and then keep stable until the end of the lifetime. Comparisons between the present experimental results and the results predicted by the empirical models are also performed. It is deduced that the diffusion-limited evaporation model is appropriate for the small droplet, but underestimates evaporation rate of the large sessile pinned liquid droplet, while the accuracy of an empirical model considering both diffusion and natural convection depends on the experimental working medium.