Experimental Study Of Droplet Vaporization Process On The Surface Of Liquid Gallium

The vaporization of solid droplets is widely used in daily life and engineering applications.There are a lot of studies on the vaporization process of solid droplets.However,the existing studies are carried out on the rigid solid substrate surface,and the vaporization of liquid droplets on the flexible liquid metal surface is rarely reported,In this paper,the vaporization process of liquid droplets on the surface of liquid gallium is studied.The research results are helpful to understand the heat and mass transfer law of liquid droplets vaporization on the flexible liquid metal surface.Because liquid gallium will react with oxygen immediately to form an oxide film in the atmospheric environment,two methods are used to remove the influence of oxide film in the experiment.One is to use hydrochloric acid steam treatment,the other is to put liquid gallium into the glove box with oxygen concentration less than 1ppm.It is found that the liquid gallium in the glove box is closest to the property of liqui d.In this paper,the evaporation process of n-hexane droplet and deionized water droplet on the surface of liquid gallium is studied.It is found that the evaporation process of n-hexane droplet on the surface of liquid gallium mostly follows the constant contact angle evaporation mode,and that of deionized water droplet follows the constant contact line evaporation mode.It is found that under the same conditions,the spreading diameter of n-hexane droplet and deionized water droplet is the largest and the evaporation time is the shortest on the surface of liquid gallium in glove box,and the spreading diameter is the smallest and the evaporation time is the longest on the surface of liquid gallium in atmospheric environment.The evaporation time and the change of droplet shape with time were calculated by using the existing solid droplet evaporation model.Comparing the calculated results with the experimental results,it was found that the difference between the calculated results and the experimental results in the glove box was the largest,which may be because the existing models were based on the rigid surface,while the liquid gallium surface in the glove box was closer to the liquid properties,The flexible surface will promote the evaporation of droplets.The Leidenfrost phenomenon of n-pentane and HFE7100 droplets on the surface of water,liquid gallium and aluminum plate was also studied.It was found that the Leidenfrost temperature of the two working fluids on the surface of liquid gallium was higher than that on the surface of liquid gallium in glove box.The Leidenfrost temperature of the two working fluids on the surface of water was the lowest,and the Leidenfrost temperature on the surface of aluminum plate was the highest.The Leidenfrost temperatures of n-pentane droplets on water surface,liquid gallium surface and aluminum plate surface were calculated by four kinds of Leidenfrost temperature prediction models.The calculated results were compared with the experimental results.The results show that the calculated results of superheat limit model are most consistent with the experimental results of n-pentane droplets on liquid gallium surface;The calculated results of Taylor hydrodynamic model are in good agreement with the experimental results of n-pentane droplet on water surface;The calculated results of the thermodynamic homogeneous nucleation temperature prediction model are in good agreement with the experimental results of n-pentane droplet on the surface of aluminum plate.Finally,the theoretical model of the droplet morphology is established when the leidnefrost phenomenon occurs,and the calculation is carried out by using Matlab software.The calculated droplet morphology is in good agreement with the experimental results.