| 摘要: |
| 及时脱除热力除霜后冷表面残留液滴，可以延缓二次结霜。本文对室温环境下超疏水表面融霜演化行为进行了微观可视化观测，对比分析了表面倾角对裸铝表面（接触角88.0°）及超疏水表面（接触角151.1°）融霜排液的影响。实验结果表明，水平超疏水表面融霜过程存在单液膜卷曲收缩及多液滴合并两种行为，较大的静态接触角及较小的接触角滞后是促使多液滴合并的主要原因。与倾斜裸表面融霜过程存在大量残留液滴不同，超疏水表面融霜液可实现自排除；当倾角＞30°时，超疏水表面排液率可达90%以上。结合表面润湿特性及表面倾角推导出表面液滴临界脱落半径，与实验结果吻合较好。 |
| 关键词: 超疏水表面 融霜特性 排液率 表面倾角 |
| DOI： |
| Received:October 24, 2018Revised:March 28, 2019 |
| 基金项目: |
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| Defrosting Evolution Behavior and Drainage Characteristic on Superhydrophobic Surface |
|
Li Shuai, Qian Chenlu, Li Dong, Zhao Xiaobao
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| (Engineering Laboratory of Energy System Process Conversion and Emission Reduction Technology of Jiangsu Province, School of Energy and Mechanical Engineering, Nanjing Normal University) |
| Abstract: |
| After traditional thermal defrosting, a great number of water droplets still retain on the surface, which can become the base of secondary frosting and accelerate secondary frosting. Therefore, duly removing retained droplets after defrosting is of great importance. In this paper, the frost melting evolution on a superhydrophobic surface was visually observed and the effects of the surface inclination angle on defrosting droplet drainage from a bare surface and superhydrophobic surface (with a static contact angle of 88.0°and 151.1°respectively) were comparatively analyzed. The experimental results showed that the defrosting droplets, as an ice-water mixture, suspended on asuperhydrophobic surface with a Cassie state during the defrosting process on a horizontal superhydrophobic surface. Two kinds of behaviors, namely, single-film curling and multi-droplets coalescence, can be seen during the defrosting processes, due to a large static contact angle and tiny contact angle hysteresis. Most of defrosting droplets on an inclined superhydrophobic surface can be self-drained accompanied with ice-water mixture rolling and stripping, which differ from the bare surface. When the inclination angle is greater than 30°, the drainage ratio of the superhydrophobic surface can reach more than 90%, while that of the bare surface can only reach 70%. Furthermore, mechanical analysis of droplets on an inclined surface was applied. The critical droplet-slipping radius was deduced according to the surface wetting characteristics and surface inclination angle, which were consistent with the experiment results. |
| Key words: superhydrophobic surface defrosting characteristics drainage ratio surface inclination angle |
