Dopphoopha Benjamin, Li Keqiao, Lin Chongjia, Huang Baoling
The Department of Mechanical and Aersopace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
The Department of Mechanical and Aersopace Engineering, Foshan Research Institute for Smart Manufacturing, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Nanophotonics. 2024 Jan 18;13(5):659-668. doi: 10.1515/nanoph-2023-0664. eCollection 2024 Mar.
Radiative cooling may serve as a promising option to reduce energy consumption for space cooling. Radiative cooling paints provide a cost-effective and scalable solution for diverse applications and attract great attention, but the state-of-art cooling paints generally use non-eco-friendly organic solvents and need large thicknesses (>400 μm) to realize high performance, which leads to high cost and environmental issues in implementation. This work aims to address these challenges by developing eco-friendly aqueous paints with low thickness (below 150 μm) by adopting a double-layer design based on a complementary spectrum strategy. The structure consists of a wide bandgap top layer to scatter short-wavelength light and a bottom layer with high reflectance to visible and near-infrared (NIR) irradiation. Effects of different design factors are studied using numerical simulation and experiments to attain the optimal design. The resulting YO-ZnO paints show a strong reflectance of 95.4 % and a high atmospheric window emissivity of 0.93 at a low thickness of 150 μm. Field tests in the subtropic humid climate of Hong Kong demonstrated sub-ambient cooling of 2 °C at noon and 4 °C at night without shielding convection. The paints also show high robustness and excellent resistance to water and UV light attacks, rendering them promising for large-scale applications.
辐射冷却可能是减少空间制冷能耗的一个有前景的选择。辐射冷却涂料为各种应用提供了一种经济高效且可扩展的解决方案，并引起了广泛关注，但目前最先进的冷却涂料通常使用不环保的有机溶剂，并且需要较大的厚度（>400μm）才能实现高性能，这导致了实施过程中的高成本和环境问题。这项工作旨在通过采用基于互补光谱策略的双层设计，开发低厚度（低于150μm）的环保水性涂料来应对这些挑战。该结构由一个用于散射短波长光的宽带隙顶层和一个对可见光和近红外（NIR）辐射具有高反射率的底层组成。使用数值模拟和实验研究了不同设计因素的影响，以实现优化设计。所得的YO-ZnO涂料在150μm的低厚度下显示出95.4%的强反射率和0.93的高大气窗口发射率。在香港亚热带潮湿气候下的现场测试表明，在无遮蔽对流的情况下，中午可实现低于环境温度2°C的冷却，夜间可实现4°C的冷却。这些涂料还表现出高稳健性以及对水和紫外线攻击的优异抗性，使其在大规模应用方面具有前景。
