Xu Ruina, Zhou Jimin, Liao Zhiyuan, Li Xiaoyang, Hu Haowei, Hu Kehui, Jiang Peixue
Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing, 100084, China.
State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing, 100084, China.
Adv Mater. 2024 Dec;36(50):e2312765. doi: 10.1002/adma.202312765. Epub 2024 Nov 6.
Extreme thermal conditions with heat flux densities exceeding 1 MW m or temperatures reaching up to 1000 °C are prevalent in various situations. However, thermal protection ability depends on specialized materials or is currently limited with existing cooling schemes. Herein, an innovative cooling scheme that relies on evaporation-driven capillary flow, enhanced by nanoengineering-designed porous structures with common materials, is proposed. Experimentally-obtained capillary flow cooling curve identifies critical heat flux corresponding to evaporation-driven flow stage, where coolants cool the surface and subsequent vapor impedes heat transfer from thermal boundaries. Nanoengineering provides opportunities for enhanced capillary flow, which proves to endow bronze, TC4 (titanium alloy, Ti-6Al-4V), and AlO with thermal protection ability 50-180% higher than that without nanoengineering-designed. The authors' scheme achieves critical heat flux up to 2.0-3.1 MW m and performs thermal dissipation capacity almost twice higher than inherent latent heat of coolant. Further, in a supersonic wind tunnel with total temperature reaching up to 1792 K, this scheme effectively protects surfaces by cooling them to surface temperatures below 500 K. Nanoengineering-enhanced capillary cooling gives access to the application of common materials for high-temperature and high-heat-flux environments and paves the way for development of lightweight, long-lasting, and large-scale solutions for thermal protection.
在各种情况下，热流密度超过1兆瓦/平方米或温度高达1000℃的极端热条件普遍存在。然而，热防护能力取决于特殊材料，或者目前现有的冷却方案存在局限性。在此，提出了一种创新的冷却方案，该方案依靠蒸发驱动的毛细流动，并通过纳米工程设计的多孔结构与常见材料相结合来增强。通过实验获得的毛细流动冷却曲线确定了与蒸发驱动流动阶段相对应的临界热流，在此阶段，冷却剂冷却表面，随后产生的蒸汽阻碍热从热边界传递。纳米工程为增强毛细流动提供了机会，事实证明，这使青铜、TC4（钛合金，Ti-6Al-4V）和AlO的热防护能力比未经过纳米工程设计时高出50%-180%。作者的方案实现了高达2.0-3.1兆瓦/平方米的临界热流，其散热能力几乎比冷却剂的固有潜热高出一倍。此外，在总温高达1792K的超音速风洞中，该方案通过将表面冷却至500K以下有效地保护了表面。纳米工程增强的毛细冷却使得常见材料能够应用于高温和高热流环境，并为开发用于热防护的轻质、持久和大规模解决方案铺平了道路。
