Vapor condensation with daytime radiative cooling
Vapor condensation with daytime radiative cooling
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DOI：
10.1073/pnas.2019292118
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
Ming Zhou;Haomin Song;Xingyu Xu;A. Shahsafi;Yurui Qu;Zhenyang Xia;Z. Ma;M. Kats;Jia Zhu
中科院分区：
文献类型：
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作者：
Ming Zhou;Haomin Song;Xingyu Xu;A. Shahsafi;Yurui Qu;Zhenyang Xia;Z. Ma;M. Kats;Jia Zhu
意义传统上，被动式蒸汽冷凝的冷却主要由对流和传导提供。然而，当蒸汽温度接近环境空气温度时，这些机制不起作用。在这样的温度下，辐射冷凝仍然有效。然而，现有的辐射蒸汽冷凝器必须在夜间运行。在这里，一种新的辐射冷却技术被应用于延长辐射凝结到白天和夜间。该技术使用工程热辐射器，不需要光刻或其他昂贵的制造技术，可以制造成覆盖大面积。当与传统的对流和传导冷凝器相结合时，这种被动技术可能会使被动水技术的产水率增加一倍。辐射蒸汽冷凝器以红外辐射的形式散发热量，并将自身冷却到环境空气温度以下，以从蒸汽中产生液态水。几个世纪以来，这种效应一直为人们所知，一些昆虫利用这种效应在干燥的沙漠中生存。人类也一直在使用辐射冷凝来收集露水。然而，所有现有的辐射蒸汽冷凝器必须在夜间运行。在这里，我们开发了一天24小时持续运行的日间辐射冷凝器。这些日间辐射冷凝器可以在阳光直射下从蒸汽中产生水，而不需要消耗能量。与传统的通过对流和传导的被动冷却相结合，辐射冷却可以大大提高被动蒸汽冷凝的性能，这可以用于被动水提取和净化技术。
Significance Traditionally, the cooling for passive vapor condensation is mainly provided by convection and conduction. However, these mechanisms do not work when the vapor temperature is near the ambient air temperature. At such temperatures, radiative condensation remains effective. However, existing radiative vapor condensers must operate during the nighttime. Here, a novel radiative-cooling technique is applied to extend radiative condensation to both daytime and nighttime. The technique uses engineered thermal radiators that do not require lithography or other costly fabrication techniques and can be manufactured to cover large areas. When combined with traditional convective and conductive condensers, this passive technology can potentially double the water production rate for passive water technologies. A radiative vapor condenser sheds heat in the form of infrared radiation and cools itself to below the ambient air temperature to produce liquid water from vapor. This effect has been known for centuries, and is exploited by some insects to survive in dry deserts. Humans have also been using radiative condensation for dew collection. However, all existing radiative vapor condensers must operate during the nighttime. Here, we develop daytime radiative condensers that continue to operate 24 h a day. These daytime radiative condensers can produce water from vapor under direct sunlight, without active consumption of energy. Combined with traditional passive cooling via convection and conduction, radiative cooling can substantially increase the performance of passive vapor condensation, which can be used for passive water extraction and purification technologies.