Abstract Recent development in spectral selective metamaterials makes daytime radiative cooling possible by engineering the material surface to achieve high reflectance in the solar irradiation waveband (0.3–2.5 μm) but high emissivity in the 8–13 μm atmospheric window. In this paper, a spectral selective polymer-based metamaterial was applied on top of a shallow aluminum box that contained with an enclosed body of water for daytime radiative cooling. The performance of such a system was compared to a similar bare Aluminum alloys plate; and a similar one with an Aluminum foil covered plate. The water temperatures were continuously measured for the three cases in a 72-hour period. The results showed that the metamaterial can effectively achieve daytime radiative cooling effect and maintain a consistent water temperature below the ambient air temperature for 2–14 °C. In contrast, the water temperatures in the aluminum foil covered plate and the bare aluminum alloy plate were above the ambient for a 10 °C and 15 °C max during the daytime. The radiative cooling power of the metamaterial water plate was also computed to be of 15–100 W/m2 during the daytime. Finally, the validated radiative cooler model was numerically studied for serving as “free cooling” source for a typical single-house building. Properly integrated into a radiant floor hydronic cooling system, the radiative cooler was found to be able to compensate >60% of annual cooling electricity consumptions. The study shed insights on the potential of applying daytime radiative cooling component and systems in buildings as a sustainable design measure to significantly reduce peak cooling load and annual cooling energy consumptions.

中文翻译：

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使用基于光谱选择性超材料的冷却表面对封闭水进行日间辐射冷却

摘要 光谱选择性超材料的最新发展使日间辐射冷却成为可能，通过设计材料表面以在太阳辐射波段（0.3-2.5 μm）中实现高反射率，但在 8-13 μm 大气窗口中实现高发射率。在这篇论文中，一种基于光谱选择性聚合物的超材料被应用在一个浅铝盒的顶部，该铝盒装有封闭的水体，用于白天的辐射冷却。将这种系统的性能与类似的裸铝合金板进行了比较；和一个类似的铝箔覆盖板。在 72 小时内连续测量三种情况的水温。结果表明，超材料可以有效地实现白天的辐射冷却效果，并使水温保持在环境空气温度以下 2-14°C 的一致。相比之下，铝箔覆盖板和裸铝合金板中的水温在白天最高 10 °C 和 15 °C 时高于环境温度。在白天，超材料水板的辐射冷却功率也计算为 15-100 W/m2。最后，对经过验证的辐射冷却器模型进行了数值研究，以用作典型单户住宅的“自由冷却”源。发现辐射冷却器正确集成到地板辐射循环冷却系统中，能够补偿超过 60% 的年度冷却电力消耗。