Enhanced boiling heat transfer on composite porous surface
Enhanced boiling heat transfer on composite porous surface
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DOI：
10.1016/j.ijheatmasstransfer.2014.08.048
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发表时间：
2015
影响因子：
5.2
通讯作者：
Pengfei Xu;Qiang Li;Y. Xuan
中科院分区：
文献类型：
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作者：
Pengfei Xu;Qiang Li;Y. Xuan
制备了复合多孔表面来研究去离子水的饱和池沸腾。扫描电镜（SEM）显微图显示，多孔层包含3种类型的孔隙结构，包括直径200 μm以上的宏观孔隙结构、直径2 μm左右的微观孔隙结构和直径400 nm左右的枝晶结构。结果表明：涂层厚度分别为33 μm、84 μm和156 μm，随着涂层厚度的增加（35°、8°和0°），去离子水与多孔表面的接触角减小；涂层的最高孔隙率为94.4%。池沸腾换热实验结果表明，临界热流密度随表面润湿性和涂层厚度的增加而增大，而表面润湿性对成核沸腾换热的影响较为复杂。多孔表面的最高CHF为239 W/cm2，比普通表面高101%。采用高速摄影技术对气泡行为进行了观察，探讨了强化核沸腾的机理。可视化数据表明，在高热流密度范围内，多孔表面上的聚结气泡比普通表面上的气泡生长更快，气泡尺寸更大。因此，气泡的离开带来了更多的液体补充，从而获得了传热系数的持续上升和更高的CHF值。
Composite porous surfaces were prepared to investigate the saturated pool boiling of de-ionized water. Scanning electron microscope (SEM) micrographs showed that the porous layers contains three types of structures, including macro pores above 200 μm diameter, micro pores around 2 μm diameter and dendritic structure around 400 nm diameter. Results showed that, the thickness of the coating layers was 33 μm, 84 μm, 156 μm and the contact angle of de-ionized water against the porous surface reduced with the increase of the coating thickness (35°, 8° and 0°). The highest porosity of the coating layers was 94.4%. The experimental results of pool boiling heat transfer indicated that the critical heat flux (CHF) increased with surface wettability and coating thickness, while the effect of the surface wettability on nucleate boiling heat transfer was complicated. The highest CHF of the porous surface was 239 W/cm2, which is 101% higher than that of plain surface. High speed photography was used to observe the bubble behaviors in order to investigate the mechanism of enhanced nucleate boiling. Visualization data indicated that the coalescent bubble on porous surface grew more quickly and the bubble size was larger than that on plain surface under high heat flux range. Consequently, the departure of bubble brought more liquid replenishment, and thus to obtain the continuous rise of heat transfer coefficient and higher CHF value.