An experimental study of nucleate pool boiling is conducted on the GNP/Ni-Al₂O₃ (GNP-graphene nano particle) nano-composite coated copper surfaces at atmospheric pressure using distilled water (DI) as boiling fluid. The microporous coated surfaces are fabricated using hybrid method (electrochemical deposition of GNP and nano-composite coating of Ni-Al₂O₃). A modified surface structure is generated as a result of this deposition, and different surface morphological parameters of this modified structure, such as surface structure, roughness and wettability, are investigated. Results show the enhancement in boiling heat transfer coefficient (BHTC) and critical heat flux (CHF) in nano-composite coated surfaces compared to the bare Cu surface. The improvement in boiling performance is mostly attributable to the enhancement of roughness and wettability as well as the higher thermal conductivity of the GNP/Ni-Al₂O₃ nano-coating. The highest CHF of 2217 (kW/m²) and BHTC of 112.83 (kW/m²K) is found in case of composite nano-coated superhydrophilic (CNCS) surfaces, which are 104% and 123% more than the bare Cu surface. High-speed visualization is used to conduct a quantitative investigation of the dynamics of bubble, including active bubble site density, emission frequency of the bubble, bubble departure diameter and their impact on the performance of pool boiling heat transfer.

Graphical Abstract

中文翻译：

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通过新型混合方法制造的微/纳米孔涂层表面的池沸腾性能增强

以蒸馏水(DI)为沸腾流体，在大气压下对GNP/Ni-Al ₂ O _{3 (GNP-石墨烯纳米颗粒)纳米复合材料涂层铜表面进行核池沸腾实验研究。采用混合方法（电化学沉积 GNP 和 Ni-Al 2} O ₃纳米复合涂层）制备微孔涂层表面）。由于该沉积而产生了改性表面结构，并且研究了该改性结构的不同表面形态参数，例如表面结构、粗糙度和润湿性。结果表明，与裸铜表面相比，纳米复合涂层表面的沸腾传热系数 (BHTC) 和临界热通量 (CHF) 有所提高。_{沸腾性能的改善主要归因于GNP/Ni-Al 2} O ₃纳米涂层的粗糙度和润湿性的增强以及更高的导热率。最高CHF为2217（kW/m ²），BHTC为112.83（kW/m ²K) 在复合纳米涂层超亲水 (CNCS) 表面的情况下被发现，比裸铜表面多 104% 和 123%。利用高速可视化技术对气泡动力学进行定量研究，包括气泡活跃点密度、气泡发射频率、气泡离开直径及其对池沸腾传热性能的影响。

图形概要