Effect of stabilizing heat treatment on condensation heat transfer performance of laser micro-/nano-textured copper surf
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Effect of stabilizing heat treatment on condensation heat transfer performance of laser micro-/nano-textured copper surface Deyuan Lou1, Sheng Mei1, Bo Wang1, Teng Li1, Jianfeng Cao1, Qibiao Yang1, Qing Tao1, Jian Cheng1, and Dun Liu1,* 1
School of Mechanical Engineering, Hubei University of Technology, Wuhan 430068, Hubei, China
Received: 5 June 2020
ABSTRACT
Accepted: 13 October 2020
The surface reforming method of metal superhydrophobic surface usually utilizes organic matter, which has the problems of serious environmental pollution, high thermal resistance, low processing efficiency, as well as easy to fall off. According to the application requirements of steam condensation heat transfer on copper surface, a laser micro-/nano-texturing technology assisted by green post-processing method is proposed in this study. In this technology, a nanosecond laser was used to texture the surface of pure copper, which will undergo heat treatment to prepare a superhydrophobic surface with micro-/nano-level structures. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to analyze the microstructure changes. A contact angle tester was used to measure the wettability of the surfaces and surface Gibbs energy. Furthermore, steam condensation system was set up to assess surface heat transfer performance. The results show that the laser micro-/nano-textured copper surface has a superhydrophilic contact angle of 4°; after heat treatment, it reaches 161° and became a superhydrophobic surface. As the heat treatment promotes fully oxidation of the textured copper surface, the surface energy is greatly reduced. Due to the formation of nanoscale CuO ‘‘clusters’’ transferred from laser-textured Cu2O by heat treatment, the superhydrophobic surface blocks the growth of condensate droplets and increases the condensation heat transfer coefficient by 4 times to 730.4 W m-2 K-1. It provides a green nonchemical treatment method for heat transfer applications of copper alloy components in the fields of energy, chemical engineering, refrigeration, microelectronics, and batteries.
Published online: 11 November 2020
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
Handling Editor: Joshua Tong.
Address correspondence to E-mail: [email protected]
https://doi.org/10.1007/s10853-020-05454-0
3982 Introduction Steam condensation heat transfer is widely used in chemical engineering, energy, nuke industry, medicine, microelectronics, battery and other fields [1, 2]. There are two types of condensation methods: dropwise condensation and film condensation. The condensing heat transfer coefficient is one order of magnitude higher than that of film consideration. Since the discovery of dropwise condensation in the 1930s, many researchers have studied the macro- and micro-heat transfer mechanisms, implementation methods, heat transfer performance, surface preparation and industrial applications of dropwise condensation as an efficient heat transfer method. A lot of research work has been done. Widely ac
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