Daytime radiative freezing

Yi Zhang; Chenglong She; Jingjing Chen; Xiaobo Yin

doi:10.1117/12.3027412

4 October 2024 Daytime radiative freezing

Yi Zhang, Chenglong She, Jingjing Chen, Xiaobo Yin

Author Affiliations +

Proceedings Volume PC13132, Nonimaging Optics: Efficient Design for Illumination and Concentration XIX; PC131320K (2024) https://doi.org/10.1117/12.3027412
Event: Optical Engineering + Applications, 2024, San Diego, California, United States

Conference Poster

Abstract

Terrestrial radiative cooling utilizes materials that allow solar radiation to pass through or reflect away while efficiently radiating heat across the atmospheric transmission window. Here we show that liquid water, when its thickness is in a proper range, is highly transparent to the solar spectrum and emits strongly in the infrared. By incorporating a solar reflector underneath, a thin water layer of proper thickness exhibits a solar reflectivity of 96.6% and a thermal emissivity of 0.94. During outdoor testing, the water-based radiative cooler achieved sub-ambient temperatures of 6 °C at noon and 11 °C around 18:00 when direct sunlight was absent. Notably, the water temperature remained below freezing for most of the day, despite ambient temperatures above 0 °C.

Citation Download Citation

Yi Zhang, Chenglong She, Jingjing Chen, and Xiaobo Yin "Daytime radiative freezing", Proc. SPIE PC13132, Nonimaging Optics: Efficient Design for Illumination and Concentration XIX, PC131320K (4 October 2024); https://doi.org/10.1117/12.3027412

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