Morphological change of plain and nano-porous surfaces during boiling and its effect on nucleate pool boiling heat transfer
Morphological change of plain and nano-porous surfaces during boiling and its effect on nucleate pool boiling heat transfer
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DOI：
10.1016/j.expthermflusci.2012.02.011
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发表时间：
2012-07-01
影响因子：
3.2
通讯作者：
Kim, Kwang J.
中科院分区：
文献类型：
--
作者：
Lee, Chi Young;Zhang, Bong June;Kim, Kwang J.
为了研究饱和水中成核池沸腾换热特性，制备了普通铝合金表面（6061，未经处理）和独特制备的氧化铝纳米多孔表面（NPS）样品。总的来说，NPS表面在核沸腾开始时表现出较低的壁面过热度和较高的核沸腾传热系数。实验还发现，经过5次重复沸腾试验后，核沸腾传热系数在普通表面下降了30%，在NPS表面下降了37%。结果发现，这两种测试样品的性能下降主要是由于在沸点表面形成氢氧化铝。我们认为，氢氧化铝在两个沸点表面形成，明显改变了沸点后表面的微观形貌，导致活性成核位点的减少。虽然NPS是提高核池沸腾换热系数的一个很好的工具，但它的寿命和实用性可能会受到与工作流体的不良表面反应的影响。(C) 2012爱思唯尔公司版权所有。
In order to investigate nucleate pool boiling heat transfer characteristics in saturated water, a plain aluminum alloy surface (6061, untreated) and a uniquely fabricated aluminum oxide Nano-Porous Surface (NPS) sample were prepared. Generally, the NPS exhibited a lower wall superheat at the onset of nucleate boiling and a higher nucleate boiling heat transfer coefficient than the plain surface. It was also noted that the nucleate boiling heat transfer coefficient decreased by 30% on the plain surface and by 37% on the NPS after five repeated boiling tests. It was found that such performance-degradation in both of the test samples was due primarily to the formation of aluminum hydroxide on the boiling surfaces. It is our belief that the aluminum hydroxide, formed on both boiling surfaces, significantly altered the surface morphologies as shown in the microscopic images of the post-boiling surfaces, which resulted in the decrease of the active nucleation sites. Although NPS is an excellent tool to enhance the nucleate pool boiling heat transfer coefficient, its life span and usefulness can be impeded by undesirable surface reactions with working fluids. (C) 2012 Elsevier Inc. All rights reserved.