Bilayer structured coating for radiative cooling applications

Abstract. Daytime radiative cooling technology can cool objects to sub-ambient temperatures under direct sunlight without energy consumption. The technology relies on high reflectance of solar irradiation and high emissivity in the atmospheric window (infrared emission with 8 to 13 μm wavelengths). We report a bilayer structured coating for passive daytime sub-ambient radiative cooling. The bilayer radiative cooling coating has high solar reflectance (0.94), and high infrared emissivity (0.96) in the atmospheric window. The bilayer coating achieved a sub-ambient temperature of 3.6°C under solar irradiance of 990  W  /  m2 at an ambient temperature of 26.6°C, and the averaged sub-ambient cooling temperature of ∼8  °  C during the night. A test with two model rooms shows that the indoor air temperature reached a maximum difference of 9.7°C between the one with the bilayer coating and that with normal white coating.

[1]  Bin Zhu,et al.  Scalable and hierarchically designed polymer film as a selective thermal emitter for high-performance all-day radiative cooling , 2020, Nature Nanotechnology.

[2]  Xiaobo Yin,et al.  Selection of polymers with functional groups for daytime radiative cooling , 2019, Materials Today Physics.

[3]  Jun Zhou,et al.  Transparent Polymer Coatings for Energy-Efficient Daytime Window Cooling , 2020 .

[4]  Yuan Yang,et al.  Paints as a Scalable and Effective Radiative Cooling Technology for Buildings , 2020 .

[5]  N. Yu,et al.  Hierarchically porous polymer coatings for highly efficient passive daytime radiative cooling , 2018, Science.

[6]  Xiaobo Yin,et al.  Terrestrial radiative cooling: Using the cold universe as a renewable and sustainable energy source , 2020, Science.

[7]  X. Ruan,et al.  Full Daytime Sub-ambient Radiative Cooling in Commercial-like Paints with High Figure of Merit , 2020, Cell Reports Physical Science.

[8]  M. Ma,et al.  Analysis of the impact of a novel cool roof on cooling performance for a low-rise prefabricated building in China , 2021 .

[9]  Marc Abou Anoma,et al.  Passive radiative cooling below ambient air temperature under direct sunlight , 2014, Nature.

[10]  D. J. Fixsen,et al.  THE TEMPERATURE OF THE COSMIC MICROWAVE BACKGROUND , 2009, 0911.1955.

[11]  Xiuqiang Li,et al.  Multispectral Thermal Management Designs for Net-Zero Energy Buildings , 2020 .

[12]  Xiaobo Yin,et al.  Subambient Cooling of Water: Toward Real-World Applications of Daytime Radiative Cooling , 2019, Joule.

[13]  X. Ruan,et al.  Ultrawhite BaSO4 Paints and Films for Remarkable Daytime Subambient Radiative Cooling. , 2021, ACS applied materials & interfaces.

[14]  Ronggui Yang,et al.  Scalable-manufactured randomized glass-polymer hybrid metamaterial for daytime radiative cooling , 2017, Science.

[15]  Lin Lu,et al.  Comprehensive evaluation of thermal and energy performance of radiative roof cooling in buildings , 2021 .

[16]  Jelena Srebric,et al.  A radiative cooling structural material , 2019, Science.

[17]  Xiaobo Yin,et al.  Radiative sky cooling: Fundamental principles, materials, and applications , 2019, Applied Physics Reviews.