Condensation of water on metallic surfaces is critical for multiple energy conversion processes. Enhancement in condensation heat transfer efficiency often requires surface texturing and hydrophobicity, usually achieved through coatings, to maintain dropwise condensation. However, such surface treatments face conflicting challenges of minimal coating thermal resistance, enhanced coating durability, and scalable fabrication. This study presents a thin (≈2 µm) polytetrafluoroethylene–carbon nanofiber nanocomposite coating that meets these challenges and sustains coalescence‐induced jumping droplet condensation for extended periods under highly demanding condensation conditions. Coating durability is achieved through improved substrate adhesion by depositing a submicron thick aluminum primer layer. Carbon nanofibers in a polytetrafluoroethylene matrix increase coating thermal conductivity and promote spontaneous surface nanotexturing to achieve superhydrophobicity for condensate microdroplets. The coating material can be deposited through direct spraying, ensuring economical scalability and versatility for a wide range of substrates. No other coating is known for metallic surfaces that is able to sustain jumping dropwise condensation under shear of steam at 111 °C flowing at ≈3 m s⁻¹ over the surface for 10 h and dropwise condensation for an additional 50 h. Up to ≈900% improvement in condensation heat transfer coefficient is achieved compared to conventional filmwise condensation.

中文翻译：

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可喷涂的薄而坚固的碳纳米纤维复合涂层，可实现极佳的逐滴冷凝性能

水在金属表面上的冷凝对于多种能量转换过程至关重要。冷凝水传热效率的提高通常需要表面纹理化和疏水性（通常通过涂层实现），以保持逐滴冷凝。然而，这样的表面处理面临最小的涂层热阻，增强的涂层耐久性和可扩展的制造的矛盾挑战。这项研究提出了一种薄的（约2 µm）聚四氟乙烯-碳纳米纤维纳米复合材料涂层，它可以应对这些挑战，并在高要求的凝结条件下长时间维持聚结引起的跳跃液滴凝结。通过沉积亚微米厚的铝底漆层，可以提高基材的附着力，从而实现涂层的耐久性。聚四氟乙烯基体中的碳纳米纤维可增加涂层的导热性，并促进自发的表面纳米结构化，以实现冷凝液微滴的超疏水性。可以通过直接喷涂来沉积涂料，从而确保了广泛的基材经济的可扩展性和多功能性。对于金属表面，尚无其他涂层能够在111°C的蒸汽剪切下维持≈3ms的蒸汽剪切下承受滴状跳跃的凝结^-1在表面上放置10小时，然后再滴加冷凝50小时。与传统的薄膜冷凝相比，冷凝传热系数提高了约≈900％。