Bubble coalescence during pool boiling with different surface characteristics
Bubble coalescence during pool boiling with different surface characteristics
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DOI：
10.1080/01457632.2023.2191438
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发表时间：
2023-03
影响因子：
2.3
通讯作者：
J. Liu;D. Orejón;Ningxi Zhang;J. Terry;A. Walton;K. Sefiane
中科院分区：
文献类型：
--
作者：
J. Liu;D. Orejón;Ningxi Zhang;J. Terry;A. Walton;K. Sefiane
摘要本文研究了在水平硅基片上的孤立腔体中池沸腾时的气泡动力学，硅基片上有三种表面涂层，氧化硅，全氟癸基三氯硅烷和二氧化硅纳米颗粒。在不同的温度下，用FC-72进行实验。在垂直聚并的情况下，观察和分析了分离气泡和随后的成核气泡之间的边界处的聚并。垂直聚结出现在全氟癸基三氯硅烷涂层表面上，由于初始气泡生长速度比其他表面快，因此聚结度较低。然而，垂直聚结对气泡离开直径的影响有限，其几乎保持恒定在0.6 mm左右。在水平聚结的情况下，在二氧化硅纳米颗粒涂覆的表面上生长的气泡能够聚结为具有比其他表面低的结晶度的小腔间距。来自间隔0.50 mm的腔的聚结气泡可以在聚结后立即分离，而对于0.25 mm的较短间隔，气泡保持附着在表面上，并且需要进一步生长以使其分离。通过对单位面积能量损失的分析，发现当空泡间距接近单个气泡的脱离直径时，可以获得最佳的换热性能。
Abstract This work investigates the bubble dynamics during pool boiling from isolated cavities on a horizontal silicon substrate with three surface coatings, silicon oxide, Perfluorodecyltrichlorosilane, and silica nanoparticles. The experiments were conducted with FC-72 under various superheat degrees. In the case of vertical coalescence, coalescences at the boundary between the departed bubble and the subsequent nucleated bubble were observed and analyzed. Vertical coalescence appears with lower superheat degrees on Perfluorodecyltrichlorosilane coated surfaces due to the faster initial bubble growth than on the other surfaces. However, the vertical coalescence has a limited effect on the bubble departure diameter, which is nearly kept constant at around 0.6 mm. In the case of horizontal coalescence, bubbles growing on the silica nanoparticles coated surface are able to coalesce for small cavity spacing with lower superheat degree than other surfaces. Coalescing bubbles from cavities spaced 0.50 mm apart can detach just after coalescence, while for a shorter spacing of 0.25 mm, bubbles remain attached to the surface and further growth is needed for their detachment. Based on the analysis of energy removal per unit of area, the optimal heat transfer performance may be achieved when the cavities spacing is approximate to the single bubble departure diameter.