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首页> 外文期刊>International Journal of Heat and Mass Transfer >Experimental study of condensation heat transfer on a horizontal aluminum tube with superhydrophobic characteristic
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Experimental study of condensation heat transfer on a horizontal aluminum tube with superhydrophobic characteristic

机译：具有超疏水特性的卧式铝管上冷凝水传热的实验研究

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In this study, we conducted a condensation heat transfer experiment for an observation of the condensation heat transfer performance from a superhydrophobic surface fabricated with the Self Assembled Monolayer (SAM) method. For the experiment of condensation heat transfer, we designed an experimental facility that could compare a superhydrophobic tube and a bare tube under the same conditions. The experiment was conducted according to a condition number defined by the coolant Reynolds number and the saturation pressure, and two repeat tests were carried out to analyze the attached condensation. Each condensation phenomenon was observed by a camera, and the droplet detaching frequency was measured in units of [drops/min]. As a result, the dropwise condensation was observed under the condition #1 and #2 in the superhydrophobic tube, and the performance was improved by about 105% over the bare tube with regard to the average overall heat transfer coefficient. Under the conditions #3 and #4, the flooded condensation was observed, and the performance improved by about 16%. By contrast, the attached condensation with a lower detaching frequency than the flooded condensation was observed under the condition #5, and a performance degradation of about 20% was observed. In addition, the condensation performance was analyzed with a ratio of the condensation thermal resistance to a total thermal resistance. As a result of the condensation thermal resistance, the ratio decreased greatly than that of the bare tube when the dropwise condensation occurred, and it was slightly decreased in the condition of the flooded condensation, and it increased in attached condensation. In the repeat tests, after passing the attached condensation, we observed that the performance of the condition #2 was further decreased compared with the situation after passing only the flooded condensation. From the result, attached and flooded condensation seemed to be related to the droplet pinning depth, and we predicted that the droplet pinning depth of attached condensation would be deeper than that of flooded condensation. In conclusion, attached condensation more seriously affects the condensation performance degradation than flooded condensation. Therefore, it is necessary to understand the condition of attached condensation and to prevent attached condensation phenomenon. (C) 2019 Elsevier Ltd. All rights reserved.
机译：在这项研究中，我们进行了冷凝传热实验，以观察用自组装单层（SAM）方法制成的超疏水表面的冷凝传热性能。对于冷凝传热的实验，我们设计了一个实验设备，可以在相同条件下比较超疏水管和裸管。根据由冷却剂雷诺数和饱和压力定义的条件数进行实验，并进行了两次重复测试以分析附着的冷凝物。用照相机观察每种凝结现象，并以[滴/分钟]为单位测量液滴分离频率。结果，在超疏水管中在＃1和＃2条件下观察到滴状冷凝，并且相对于平均总传热系数，性能比裸管提高了约105％。在＃3和＃4的条件下，观察到溢流的冷凝水，性能提高了约16％。相反，在条件＃5下，观察到附连的冷凝物的分离频率低于浸没的冷凝物，并且观察到性能下降约20％。另外，以冷凝热阻与总热阻之比来分析冷凝性能。作为冷凝热阻的结果，当发生逐滴冷凝时，该比率比裸管大幅度降低，并且在溢流冷凝的情况下该比率略有降低，并且在附着的冷凝中该比率增加。在重复测试中，通过附着的冷凝水后，我们发现与仅通过淹没冷凝水后的情况相比，条件2的性能进一步下降。从结果来看，附着和淹没凝结似乎与液滴的钉扎深度有关，我们预测附着的凝结的液滴钉扎深度将比淹没的凝结更深。总之，附着的凝结比淹没的凝结更严重影响凝结性能的下降。因此，有必要了解附着的凝结情况并防止附着的凝结现象。 （C）2019 Elsevier Ltd.保留所有权利。

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