Aqueous double-layer paint of low thickness for sub-ambient radiative cooling

Radiative cooling may serve as a promising option to reduce energy consumption for space cooling. Radiative cooling paints provide a cost-effective and scalable solution for diverse applications and attract great attention, but the state-of-art cooling paints generally use non-eco-friendly organic s...

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Main Authors: Dopphoopha Benjamin, Li Keqiao, Lin Chongjia, Huang Baoling
Format: Article
Language:English
Published: De Gruyter 2024-01-01
Series:Nanophotonics
Subjects:
Online Access:https://doi.org/10.1515/nanoph-2023-0664
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author Dopphoopha Benjamin
Li Keqiao
Lin Chongjia
Huang Baoling
author_facet Dopphoopha Benjamin
Li Keqiao
Lin Chongjia
Huang Baoling
author_sort Dopphoopha Benjamin
collection DOAJ
description Radiative cooling may serve as a promising option to reduce energy consumption for space cooling. Radiative cooling paints provide a cost-effective and scalable solution for diverse applications and attract great attention, but the state-of-art cooling paints generally use non-eco-friendly organic solvents and need large thicknesses (>400 μm) to realize high performance, which leads to high cost and environmental issues in implementation. This work aims to address these challenges by developing eco-friendly aqueous paints with low thickness (below 150 μm) by adopting a double-layer design based on a complementary spectrum strategy. The structure consists of a wide bandgap top layer to scatter short-wavelength light and a bottom layer with high reflectance to visible and near-infrared (NIR) irradiation. Effects of different design factors are studied using numerical simulation and experiments to attain the optimal design. The resulting Y2O3–ZnO paints show a strong reflectance of 95.4 % and a high atmospheric window emissivity of 0.93 at a low thickness of 150 μm. Field tests in the subtropic humid climate of Hong Kong demonstrated sub-ambient cooling of 2 °C at noon and 4 °C at night without shielding convection. The paints also show high robustness and excellent resistance to water and UV light attacks, rendering them promising for large-scale applications.
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institution OA Journals
issn 2192-8614
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publishDate 2024-01-01
publisher De Gruyter
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series Nanophotonics
spelling doaj-art-165ae25420c749859cd2b7be75beaa612025-08-20T02:23:36ZengDe GruyterNanophotonics2192-86142024-01-0113565966810.1515/nanoph-2023-0664Aqueous double-layer paint of low thickness for sub-ambient radiative coolingDopphoopha Benjamin0Li Keqiao1Lin Chongjia2Huang Baoling3The Department of Mechanical and Aersopace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, ChinaThe Department of Mechanical and Aersopace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, ChinaThe Department of Mechanical and Aersopace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, ChinaThe Department of Mechanical and Aersopace Engineering, Foshan Research Institute for Smart Manufacturing, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, ChinaRadiative cooling may serve as a promising option to reduce energy consumption for space cooling. Radiative cooling paints provide a cost-effective and scalable solution for diverse applications and attract great attention, but the state-of-art cooling paints generally use non-eco-friendly organic solvents and need large thicknesses (>400 μm) to realize high performance, which leads to high cost and environmental issues in implementation. This work aims to address these challenges by developing eco-friendly aqueous paints with low thickness (below 150 μm) by adopting a double-layer design based on a complementary spectrum strategy. The structure consists of a wide bandgap top layer to scatter short-wavelength light and a bottom layer with high reflectance to visible and near-infrared (NIR) irradiation. Effects of different design factors are studied using numerical simulation and experiments to attain the optimal design. The resulting Y2O3–ZnO paints show a strong reflectance of 95.4 % and a high atmospheric window emissivity of 0.93 at a low thickness of 150 μm. Field tests in the subtropic humid climate of Hong Kong demonstrated sub-ambient cooling of 2 °C at noon and 4 °C at night without shielding convection. The paints also show high robustness and excellent resistance to water and UV light attacks, rendering them promising for large-scale applications.https://doi.org/10.1515/nanoph-2023-0664multilayerradiative coolingmonte carlo simulationwater-based acrylic paint
spellingShingle Dopphoopha Benjamin
Li Keqiao
Lin Chongjia
Huang Baoling
Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
Nanophotonics
multilayer
radiative cooling
monte carlo simulation
water-based acrylic paint
title Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
title_full Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
title_fullStr Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
title_full_unstemmed Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
title_short Aqueous double-layer paint of low thickness for sub-ambient radiative cooling
title_sort aqueous double layer paint of low thickness for sub ambient radiative cooling
topic multilayer
radiative cooling
monte carlo simulation
water-based acrylic paint
url https://doi.org/10.1515/nanoph-2023-0664
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AT likeqiao aqueousdoublelayerpaintoflowthicknessforsubambientradiativecooling
AT linchongjia aqueousdoublelayerpaintoflowthicknessforsubambientradiativecooling
AT huangbaoling aqueousdoublelayerpaintoflowthicknessforsubambientradiativecooling