| ZHOU Bao-yu,YANG Hui,FENG Wei,JIANG Yu-feng,CHEN Yue.Self-propelled and Size Distribution of Condensate Droplets on Superhydrophobic Surfaces[J],49(5):170-176 |
| Self-propelled and Size Distribution of Condensate Droplets on Superhydrophobic Surfaces |
| Received:September 08, 2019 Revised:May 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.05.020 |
| KeyWord:superhydrophobic surfaces dropwise condensation orthogonal test self-propelled size distribution image processing |
| Author | Institution |
| ZHOU Bao-yu |
1.Hubei Polytechnic University, Huangshi , China; 2.Yunnan University, Kunming , China |
| YANG Hui |
1.Hubei Polytechnic University, Huangshi , China |
| FENG Wei |
1.Hubei Polytechnic University, Huangshi , China |
| JIANG Yu-feng |
1.Hubei Polytechnic University, Huangshi , China |
| CHEN Yue |
1.Hubei Polytechnic University, Huangshi , China |
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| Abstract: |
| The work aim to optimize the experimental parameters of preparing copper hydroxide nanostructures by electrochemical deposition and to explore the size distribution of condensate droplets on different wettability surfaces. Orthogonal test method was adopted to comprehensively consider the influence of electrolyte concentration, reaction temperature, polarization time and current density on contact angle, and its surface morphology was analyzed by SEM. At the same time, a method to quickly and accurately identify, extract and count the characteristic value of condensate droplets was proposed based on MATLAB programming software. The optimal parameters of the orthogonal test were concentration 0.5 mol/L, temperature 5 ℃, time 2000 s, current density 4 mA/cm2. Under this condition, the contact angle of the sample was up to 168.8° and the sliding angle was less than 3°. The condensation test results shown that on the superhydrophobic surface, condensate droplets can coalescence and self-propelled frequently. The average diameter of droplets was the smallest, and the proportion of droplets in the range of 1~10 μm remained at about 50%. On the hydrophobic and hydrophilic surfaces, condensation droplets can only merge, and the average diameter of droplets increased significantly. And the condensate droplet density on the superhydrophobic, hydrophobic and hydrophilic surfaces was stable at about 2000 mm-2, 1000 mm-2 and 360 mm-2 respectively, finally. We found that the nano-needle structure can minimize the solid-liquid contact area, reduce the adhesive force of condensate droplets, improve the condensate self-propelled frequency, reduce the diameter of condensate droplets, and improve the update frequency of condensate droplet, which is expected to achieve efficient condensation heat transfer. At the same time, the feasibility of the image processing method for the size distribution of condensing droplets is verified by comparison with the image-J processing results. |
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