据悉，低于环境温度的日间辐射冷却通过向外层空间发射热辐射，使温度被动地低于环境温度，即使在阳光直射下也是如此。
这项技术有望应用于许多令人激动的应用。然而，以前对低于环境温度的日间辐射冷却的演示，需要直接面向天空表面，在现实场景中普遍存在的垂直表面，如建筑物和车辆则不能直接应用。
在这项研究中，研究团队使用分层设计、角度不对称的光谱选择性热发射器，以演示峰值阳光下垂直表面的低于环境温度的日间辐射冷却。在每平方米约920瓦的峰值阳光下，发射器达到的温度比环境温度低约2.5°C，与二氧化硅—聚合物混合辐射冷却器和商用白漆相比，分别降低了约4.3°和8.9°C。
附：英文原文
Title: Subambient daytime radiative cooling of vertical surfaces
Author: Fei Xie, Weiliang Jin, J. Ryan Nolen, Hao Pan, Naiqin Yi, Yang An, Zhiyu Zhang, Xiangtong Kong, Fei Zhu, Ke Jiang, Sicong Tian, Tianji Liu, Xiaojuan Sun, Longnan Li, Dabing Li, Yun-Feng Xiao, Andrea Alu, Shanhui Fan, Wei Li
Issue&Volume: 2024-11-15
Abstract: Subambient daytime radiative cooling enables temperatures to passively reach below ambient temperature, even under direct sunlight, by emitting thermal radiation toward outer space. This technology holds promise for numerous exciting applications. However, previous demonstrations of subambient daytime radiative cooling require surfaces that directly face the sky, and these cannot be applied to vertical surfaces that are ubiquitous in real-world scenarios such as buildings and vehicles. Here, we demonstrate subambient daytime radiative cooling of vertical surfaces under peak sunlight using a hierarchically designed, angularly asymmetric, spectrally selective thermal emitter. Under peak sunlight of about 920 watts per square meter, our emitter reaches a temperature that is about 2.5°C below ambient temperature, corresponding to a temperature reduction of about 4.3° and 8.9°C compared with a silica-polymer hybrid radiative cooler and commercial white paint, respectively.
DOI: adn2524
Source: https://www.science.org/doi/10.1126/science.adn2524