Enhanced condensation heat transfer using porous silica inverse opal coatings on copper tubes.
Enhanced condensation heat transfer using porous silica inverse opal coatings on copper tubes.
复制标题
铜管上多孔二氧化硅反蛋白石涂层强化冷凝传热。
DOI：
10.1038/s41598-021-90015-x
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发表时间：
2021-05-21
影响因子：
4.6
通讯作者：
Aizenberg J
中科院分区：
文献类型：
--
作者：
Adera S;Naworski L;Davitt A;Mandsberg NK;Shneidman AV;Alvarenga J;Aizenberg J
相变冷凝在自然界和工业中都是很常见的。自20世纪30年代以来，人们已经很清楚，蒸汽在干净的金属表面上以薄膜方式凝结，而在涂有促进剂材料的表面上则形成离散的液滴。在膜式和滴式两种模式下，当重力克服钉住力时，冷凝物就会被移除。在这项工作中，我们展示了在铜管上涂上二氧化硅反蛋白石结构时，由于材料收缩而形成的裂缝中快速的冷凝物传输。重要的是，裂缝的高水力传导性促进了轴向凝结水的输送，有利于凝结水的传热。在我们的实验中，裂纹将传热系数从光滑干净的铜管上层流膜状冷凝的≈12 kW/m2 K提高到反向蛋白石涂层铜管的≈80 kW/m2 K；近七倍的膜状冷凝和相同的增强与最先进的滴状冷凝。此外，我们的研究结果表明，在多孔结构中浸渍油进一步提高了30%的换热系数，达到≈103 kW/m2 K。重要的是，与快速降解的滴滴冷凝相比，当实验重复> 20次时，反蛋白石涂层铜管仍保持较高的传热率；每个实验持续3-4小时。除了新的涂层方法之外，从这项工作中获得的见解还提出了一种策略，可以最大限度地减少润滑表面凝结过程中的油损耗。
Phase-change condensation is commonplace in nature and industry. Since the 1930s, it is well understood that vapor condenses in filmwise mode on clean metallic surfaces whereas it condenses by forming discrete droplets on surfaces coated with a promoter material. In both filmwise and dropwise modes, the condensate is removed when gravity overcomes pinning forces. In this work, we show rapid condensate transport through cracks that formed due to material shrinkage when a copper tube is coated with silica inverse opal structures. Importantly, the high hydraulic conductivity of the cracks promote axial condensate transport that is beneficial for condensation heat transfer. In our experiments, the cracks improved the heat transfer coefficient from ≈ 12 kW/m2 K for laminar filmwise condensation on smooth clean copper tubes to ≈ 80 kW/m2 K for inverse opal coated copper tubes; nearly a sevenfold increase from filmwise condensation and identical enhancement with state-of-the-art dropwise condensation. Furthermore, our results show that impregnating the porous structure with oil further improves the heat transfer coefficient by an additional 30% to ≈ 103 kW/m2 K. Importantly, compared to the fast-degrading dropwise condensation, the inverse opal coated copper tubes maintained high heat transfer rates when the experiments were repeated > 20 times; each experiment lasting 3–4 h. In addition to the new coating approach, the insights gained from this work present a strategy to minimize oil depletion during condensation from lubricated surfaces.
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作者：
Sanya AS;Akowanou C;Sanya EA;Degan G
通讯作者：
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