| LOU De-yuan,LIU Qing,MEI Sheng,YANG Shao-kun,ZHAI Zhong-sheng,ZHENG Zhong,CHENG Jian,LIU Dun.Enhancement of Condensation Heat Transfer on Stainless Steel Surface by Laser Selective Micro-texture[J],48(11):202-210 |
| Enhancement of Condensation Heat Transfer on Stainless Steel Surface by Laser Selective Micro-texture |
| Received:May 16, 2019 Revised:November 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.11.021 |
| KeyWord:304 stainless steel condensation heat transfer coefficient selective micro-texture nanosecond laser wedge- shaped channel |
| Author | Institution |
| LOU De-yuan |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| LIU Qing |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| MEI Sheng |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| YANG Shao-kun |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| ZHAI Zhong-sheng |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| ZHENG Zhong |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| CHENG Jian |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
| LIU Dun |
Key Laboratory of Modern Manufacturing Quality Engineering in Hubei Province, School of Mechanical Engineering, Hubei University of Technology, Wuhan , China |
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| Abstract: |
| The work aims to adopt the chemical-free laser selective micro-texture technology to enhance the condensing heat transfer performance of stainless steel for the disadvantages of high pollution, large thermal resistance and long processing cycle in the chemical modification method used for special wettability. The micro-textured stainless steel surface was scanned by nanosecond pulsed fiber laser to obtain a superhydrophilic surface of a square grid groove-convex structure. The surface free energy was baked in a constant temperature drying oven to obtain a stainless steel superhydrophilic surface with a contact angle of 156.7° and a rolling angle of 4.2°. The superhydrophobic surface was then processed by laser for secondary micro-texture to get a wedge-shaped superhydrophilic-superhydrophobic selected micro-textured surface. Surface morphology, chemical composition and three-dimensional profile were analyzed by SEM, XPS and three-dimensional optical microscope, respectively. By comparing the single superhydrophilic, superhydrophobic and original surfaces, the back surface temperature, the condensed water volume and the average detached diameter of the condensed droplets were measured, and the surface condensation heat transfer coefficient of the four samples was calculated according to the relevant condensing heat transfer theoretical formula. Condensation experiments showed that the condensation heat transfer coefficient of the micro-textured surface of the wedge-shaped selection could reach (159.7±1.8) W/(m2•K), about twice of single superhydrophilic surface condensation heat transfer coefficient, and the average detachment diameter of the surface condensation droplets reached 1.2 mm, about 55% of that of full super-hydrophobic surface. The heat transfer coefficient and the average detached diameter of the condensed droplets were twice and 55% respectively. The superhydrophilic wedge-shaped channel on the micro-texture surface of the selected area has a self-driving effect on the liquid flow, so that the condensate can be quickly concentrated and separated from the condensed surface. This selected micro-texture pattern has better performance than the single original, superhydrophilic and superhydrophobic surfaces. At the same time, the average detachment diameter of the surface condensation droplets decreases, thus leading to a higher condensation heat transfer coefficient. |
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