| SUN Xiao-han,DANG Chao,WANG Xiao-wei.Numerical Study on Wetting Characteristics of Special-shaped Microstructure Surface[J],52(12):160-168, 187 |
| Numerical Study on Wetting Characteristics of Special-shaped Microstructure Surface |
| Received:October 01, 2023 Revised:November 20, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.12.014 |
| KeyWord:special-shaped microstructure intrinsic contact angle wetting state low surface energy working medium geometric parameters |
| Author | Institution |
| SUN Xiao-han |
Institute of Thermal Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing , China;Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale, Beijing , China |
| DANG Chao |
Institute of Thermal Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing , China;Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale, Beijing , China |
| WANG Xiao-wei |
National Energy Group Science and Technology Research Institute Co., Ltd., Nanjing , China |
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| Abstract: |
| Superlyophobic surfaces are playing an increasingly important role in practical applications due to their excellent performance such as self-cleaning, anti-icing and droplet manipulation. In practical application, low surface energy working medium is the most widely used working medium except water, but the properties of low surface energy working medium are obviously different from water, so how to realize the control of wettability of low surface energy organic working medium has become the main concern of the industry. To investigate the mechanism of wettability regulation of low surface energy working fluid by special-shaped microstructures, simulation studies were conducted on a variety of special-shaped microstructure surfaces. VOF model was used in this work to simulate the wettability of different surface energy working media on special-shaped microstructure surface. Contact angle was an important index to measure wettability. This work focused on analyzing the effect of microstructure, spacing and upper microstructure surface width on the wetting behavior. It was found that the lyophobic performance of single-layer double reentrant microstructure was much better than that of single-layer single reentrant and cylindrical microstructures, and the superlyophobic state of low surface energy working medium with intrinsic contact angle of 5° could be achieved without relying on surface chemistry. When the spacing of the cylindrical microstructure was between 100 μm and 250 μm, the critical intrinsic contact angle was more than 90°. When the single-layer single reentrant microstructure was between 100 μm and 250 μm, the critical intrinsic contact angle was more than 19°. The lyophobicity of single-layer double reentrant microstructures to low surface energy working fluids was less affected by the spacing and width of special-shaped microstructures. The study of droplet wetting behavior showed that the smaller the solid-liquid interface contact area, the larger the apparent contact angle, and the better the lyophobic performance. At the same time, the energy barrier of the reentrant structure had a great effect on the improvement of lyophobicity. Therefore, the double-layer special-shaped microstructure with a small width of the first layer was designed to reduce the contact area and increase the energy barrier. Due to the small size of the double-layer special-shaped microstructure and the significant effect of capillary force, the surface lyophobic performance was only related to the upper microstructure, and the energy barrier of the lower structure failed. In addition, based on the research content and the wettability difference of special-shaped microstructure, a special-shaped microstructure surface which could realize directional transport of droplets was proposed. The results show that the self-drive of low surface energy droplets can be effectively realized through the surface microstructure design. Simple operation and low energy consumption are of great significance for practical applications. |
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