Effects of carbon nanotube coating on flow boiling in a micro-channel
Effects of carbon nanotube coating on flow boiling in a micro-channel
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DOI：
10.1016/j.ijheatmasstransfer.2009.02.007
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发表时间：
2009-07-01
影响因子：
5.2
通讯作者：
Fisher, Timothy
中科院分区：
文献类型：
--
作者：
Khanikar, Vikash;Mudawar, Issam;Fisher, Timothy
通过实验研究了在矩形浅微通道底壁表面涂覆碳纳米管的强化传热效果。使用水作为工作流体，用裸铜表面和三个单独但相同的CNT涂覆表面进行测试。在相同的质量速度下重复测试每个CNT涂覆的表面，以探索传热性能参数，特别是临界热通量（CHIF）的任何时间依赖性。CNT涂层的影响的可察觉的差异，观察到在高质量速度相比，低。CHF是可重复的低质量速度，但在高质量速度下重复测试后降解，证明高流速导致CNT涂覆表面的形态发生明显变化。SEM图像显示，最初接近垂直的碳纳米管在高质量速度下在加热表面上弯曲，形成重复的“鱼鳞”图案。与裸铜表面相比，鱼鳞之间的空隙提供了近零角度的空腔，增强了核沸腾区域的传热。虽然CHIF通过与CNT涂层相关的增加的传热面积而增强，但是在重复测试之后增强降低，因为CNT翅片效应受到弯曲的损害。(C)2009爱思唯尔有限公司版权所有。
Experiments were performed to assess the heat transfer enhancement benefits of coating the bottom wall of a shallow rectangular micro-channel with carbon nanotubes (CNTs). Using water as working fluid, tests were performed with a bare copper surface and three separate, yet identical CNT-coated surfaces. Each of the CNT-coated surfaces was tested repeatedly at the same mass velocity to explore any time dependence of heat transfer performance parameters, especially critical heat flux (CHIF). Appreciable differences in the influence of CNT coating were observed at high mass velocities as compared to low. CHF was repeatable at low mass velocities but degraded following repeated tests at high mass velocities, proving high flow velocities cause appreciable changes to the morphology of the CNT-coated surface. SEM images show the initially near-vertical CNTs were bent upon the heated surface at high mass velocities to form a repeated 'fish-scale' pattern. Voids between the fish scales' provided near-zero-angle cavities that enhanced heat transfer in the nucleate boiling region compared to the bare copper surface. While CHIF was enhanced by the increased heat transfer area associated with the CNT coating, the enhancement decreased following repeated tests as the CNT fin effect was compromised by the bending. (C) 2009 Elsevier Ltd. All rights reserved.