Wang Menghao, Yang Yinchuang, Sun Yiwei, Li Jian, Hao Menglong
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, PR China.
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, PR China.
Heliyon. 2023 Oct 10;9(10):e20840. doi: 10.1016/j.heliyon.2023.e20840. eCollection 2023 Oct.
The rapid development of power-intensive and flexible electronic devices requires thinner heat-dissipation devices with better thermal performance. Ultra-thin flat heat pipe (UTFHP) with striped wick structure is a promising candidate for this application, but its wick structure and thermal performance have not yet been thoroughly studied and optimized for the small concentrated heat source, which is commonly encountered in electronics. In this study, several concentrated striped composite wick (CSCW) structures for 0.6 mm thick UTFHPs are proposed and experimentally investigated. The CSCW consists of copper foam with striped passages converging in the heating zone and double layers of copper screen mesh. The thermal performance of UTFHPs with various composite wick structures is experimentally evaluated. UTFHPs with the proposed structures are also compared with a UTFHP with a more conventional parallel passage composite wick structure. Experimental results show that the CSCW with the hollow structure at the evaporation section is preferred, due to the directed liquid working medium reflux and a large vapor-liquid evaporation interface. Besides, the passage width of the copper foam significantly affects the thermal performance. With the best-performing wick structure, the UTFHP gives the lowest thermal resistance of 0.79 °C/W at a heat load of 23.34 W. Its effective thermal conductivity is approximately 7 times that of copper. The proposed striped wick structure for UTFHPs provides an alternative to handle the hot-spot challenge of electronic devices.
功率密集型和柔性电子设备的快速发展，需要具有更好热性能的更薄散热设备。具有条纹状芯结构的超薄扁平热管（UTFHP）是该应用的一个有前途的候选者，但其芯结构和热性能尚未针对电子设备中常见的小集中热源进行深入研究和优化。在本研究中，提出了几种用于0.6毫米厚UTFHPs的集中条纹复合芯（CSCW）结构，并进行了实验研究。CSCW由在加热区汇聚的带条纹通道的泡沫铜和双层铜丝网组成。对具有各种复合芯结构的UTFHPs的热性能进行了实验评估。还将具有所提出结构的UTFHPs与具有更传统的平行通道复合芯结构的UTFHP进行了比较。实验结果表明，蒸发段具有中空结构的CSCW是优选的，这是由于定向的液体工作介质回流和大的气液蒸发界面。此外，泡沫铜的通道宽度显著影响热性能。采用性能最佳的芯结构，UTFHP在23.34 W的热负荷下具有0.79°C/W的最低热阻。其有效热导率约为铜的7倍。所提出的UTFHPs条纹芯结构为应对电子设备的热点挑战提供了一种替代方案。
