Convective dropwise condensation heat transfer in mini-channels with biphilic surface
Convective dropwise condensation heat transfer in mini-channels with biphilic surface
复制标题
双亲表面微通道内的对流滴状冷凝传热
DOI：
10.1016/j.ijheatmasstransfer.2019.01.015
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发表时间：
2019-05
影响因子：
5.2
通讯作者：
JianXie
中科院分区：
文献类型：
--
作者：
Jindou Yuan;Yanbo Wang;Jinliang Xu;Xianbing Ji;JianXie
对于受限通道中的滴状冷凝（DWC），液滴在表面滑动并可能损坏纳米柱，因此纳米柱结构不适合。在这里，我们提供了具有疏水润湿性的聚合物薄膜的坚固双亲表面。在铜表面烧结网筛，形成焊接接头阵列。将烧结封装浸入聚四氟乙烯溶液中，然后通过烘烤技术形成疏水性涂膜。通过将网筛与铜基板分离来暴露亲水点。冷凝实验在尺寸为30.0×3.13×0.97mm3的微通道中进行，工质为纯水蒸气。质量通量覆盖范围为 10.5–63.8kg/m2s。结果表明，双亲表面的冷凝传热系数最大为抛光铜表面的5.54倍，疏水聚合物层表面的冷凝传热系数最大为1.89倍。具有双亲表面和疏水表面的冷凝器中的压降几乎相同。对于双亲表面上的 DWC，亲水点上生长的液滴会吸引并合并相邻的液滴，以生成定向液滴聚结，这一点可以通过吉布斯能量分析来解释。在双亲性表面上观察到比疏水性表面上更高的液滴离开频率。与疏水表面相比，双亲表面上的液滴具有不同的接触角，覆盖了多个亲水点并降低了液滴热阻。上述效应解释了双亲表面存在时的传热增强机制。
For dropwise condensation (DWC) in confined channels, droplets slide on surface and may spoil the nano-pillars, thus the nano-pillars structure is not suitable. Here, we provide a robust biphilic surface with polymer film as hydrophobic wettability. Mesh screen is sintered on copper surface to form welding junction array. Dipping the sintered package in a Teflon solution followed by baking technique forms a hydrophobic coating film. Hydrophilic dots are exposed by separating mesh screen from copper substrate. Condensation experiment was performed in a mini-channel with dimensions of 30.0 × 3.13 × 0.97 mm3and pure water–vapor as the working fluid. Mass flux covered a range of 10.5–63.8 kg/m2s. It is shown that condensation heat transfer coefficients on biphilic surface were 5.54 times of those on polished copper surface, and 1.89 times of those on hydrophobic polymer layer surface, maximally. Pressure drops are almost identical in condensers with biphilic surface and hydrophobic surface. For DWC on biphilic surface, growing droplet on hydrophilic dot attracts and merges neighboring droplets to generatedirectional-droplets-coalescence, explained by the Gibbs energy analysis. Higher droplet departure frequency was observed on biphilic surface than hydrophobic surface. Compared with hydrophobic surface, droplet on biphilic surface has different contact angle, covers several hydrophilic dots and reduces droplet thermal resistance. The above effects explain the heat transfer enhancement mechanism when biphilic surface is present.
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DOI：
10.1016/j.ijheatmasstransfer.2017.11.002
发表时间：
2018-03
影响因子：
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期刊：
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影响因子：
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发表时间：
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影响因子：
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