Passive daytime radiative cooling (PDRC) is a promising energy-saving cooling method to cool objects without energy consumption. Although numerous PDRC materials and structures have been proposed to achieve sub-ambient temperatures, the technique faces unprecedented challenges brought on by complicated and expensive fabrication. Herein, inspired by traditional Chinese oil-paper umbrellas, we develop a self-cleaning and self-cooling oil-foam composite (OFC) made of recycled polystyrene foam and tung oil to simultaneously achieve efficient passive radiative cooling and enhanced thermal dissipation of objects. The OFCs show high solar reflectance (0.90) and high mid-infrared thermal emittance (0.89) during the atmospheric transparent window, contributing to a sub-ambient temperature drop of ∼5.4 °C and cooling power of 86 W m −2 under direct solar irradiance. Additionally, the worldwide market of recycled packaging plastics can provide low-cost raw materials, further eliminating the release of plastics into the environment. The OFC offers an energy-efficient, cost-effective and environmentally friendly candidate for building cooling applications and provides a value-added path for plastic recycling.
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Continuously variable emission for mechanical deformation induced radiative cooling
Passive radiative cooling, drawing heat energy of objects to the cold outer space through the atmospheric transparent window, is significant for reducing the energy consumption of buildings. Daytime and nighttime radiative cooling have been extensively investigated in the past. However, radiative cooling which can continuously regulate its cooling temperature, like a valve, according to human need is rarely reported. In this study, we propose a reconfigurable photonic structure, based on the effective medium theory and semi-analytical calculations, for the adaptive radiative cooling by continuous variation of the emission spectra in the atmospheric window. This is realized by the deformation of a one-dimensional polydimethylsiloxane (PDMS) grating and nanoparticle-embedded PDMS thin film when subjected to mechanical stress/strain. The proposed structure reaches different stagnation temperatures under certain strains. A dynamic tuning in emissivity under different strains results in a continuously variable “ON”/“OFF” mode in a particular atmospheric window that corresponds to the deformation-induced fluctuation of the operating temperatures of the reconfigurable nanophotonic structure.
more » « less- Award ID(s):
- 1941743
- NSF-PAR ID:
- 10204308
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Materials
- Volume:
- 1
- Issue:
- 1
- ISSN:
- 2662-4443
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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