Subambient daytime cooling enabled by hierarchically architected all-inorganic metapaper with enhanced thermal dissipation

Tian, Yanpei; Liu, Xiaojie; Wang, Ziqi; Li, Jiansheng; Mu, Ying; Zhou, Shiyu; Chen, Fangqi; Minus, Marilyn L.; Xiao, Gang; Zheng, Yi

doi:10.1016/j.nanoen.2022.107085

Cited by 48 publications

(51 citation statements)

References 41 publications

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“…After adding a thin Ag bottom layer, the ε avg enhances to 0.79 at normal incidence and reaches 0.81 at θ = 25°. We note that ε avg obtained in this work is lower than recently published passive radiative coolers (∼0.9). − This is because, as mentioned earlier, we intentionally introduced the emissivity dip in 8–13 μm to pursue a lower steady-state temperature for subambient cooling. The comparison of a selective emitter with and without the emissivity dip is shown in Figure S8.…”

Section: Resultsmentioning

confidence: 69%

Machine Learning-Enabled Inverse Design of Radiative Cooling Film with On-Demand Transmissive Color

et al. 2023

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Passive radiative cooling is a cost-efficient and eco-friendly approach to cool terrestrial objects by dissipating heat to the outer space. Colored radiative cooling (CRC) has many advantages over conventional passive radiative cooling and has garnered growing interest recently. However, existing CRC films are normally opaque, where the incident sunlight is either reflected for rendering color or absorbed to generate waste heat. In this work, we design a transmissive CRC film that allows a specific portion of light to pass through and provides more vivid colors. Such a transmissive film achieves the coloration and cooling dual-function by stacking a solar transparent selective emitter on top of a nanocavity-based color filter. The top emitter is first designed by using a mixed-integer memetic algorithm, where the layer materials, their number sequence, and thicknesses are simultaneously optimized. The variability in both material composition and layer thickness enables the emitter with a near-ideal emissivity in the atmospheric windows for subambient cooling, and an ultrahigh transmissivity in the solar range for sunlight penetration. Then, the structures of bottom nanocavity are determined by using a tandem neural network for on-demand color generation. This machine learning-assisted inverse design approach provides real-time structure prediction for on-demand colors and offers great flexibility in balancing the cooling and coloring functionalities. The proposed methodology can have special significance in broadening the application of passive radiative coolers in energy-efficient buildings, power-generating windows, and sustainable greenhouses.

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Section: Resultsmentioning

confidence: 69%

Machine Learning-Enabled Inverse Design of Radiative Cooling Film with On-Demand Transmissive Color

et al. 2023

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“…The average infrared emissivity in the wavelength of 8-13 μm was calculated as where I BB (λ) is the blackbody radiation intensity; ε LWIR (λ) is the thermal emissivity in the range of 8-13 μm. [46] Infrared thermal images were taken by an infrared camera (Fluke Ti400, America). The real-time temperature change (simulation and outdoor test) was measured by using a homemade experimental setup with thermocouples (Sinomeasure Pt 100, China) connected to temperature recorders.…”

Section: Methodsmentioning

confidence: 99%

Flexible and Dual‐Sided Available Colored Films for Efficient Daytime Radiative Cooling

Zhang

Pan

et al. 2023

Adv Eng Mater

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Passive daytime radiative cooling (PDRC) is a promising strategy to realize surface cooling of objects without any external energy consumption. While such materials typically exhibit dazzling white appearances, developing pleasingly looking colored radiative cooling materials is greatly significant but remains an arduous challenge. Herein, self‐standing, flexible colored films available on both sides are prepared by using a facile and scalable strategy. The films are asymmetrically designed. One side is SiO2‐filled porous structure with highly reflective pigment distributed that can selectively reflect solar light to generate specific color, and the other side is hierarchically porous three‐phase composite with less SiO2, which maximizes the solar reflection. The breathable film achieves a relatively high near infrared reflectance on the colored side (up to 89%), and a broadband solar reflectance on the reverse side. Moreover, both sides exhibit extremely high mid‐infrared emissivity (98%) allowing significant radiative heat loss. With the diverse but efficient reflectance and emittance, different sides of three colored films yield temperature drops ranging from 2.0 to 11.1 °C during daytime. Building energy simulation indicates that 655 MJ m−2 energy can be saved over the whole summer if the dual‐sided available colored film is deployed in China.

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“…recently developed a facile but high‐performance cooling materials with hydroxyapatite, Ca 10 (OH) 2 (PO 4 ) 6 fibers, which can self‐assemble into bundles and form a porous network, resulting in high solar reflectance of 99%. [ 69 ] Moreover, the strong molecular vibrations of phosphate radical can provide high mid‐infrared emissivity of ≈90%. Therefore, the developed cooling meta‐paper can yield a temperature drop of 5.1 K under the solar irradiance of 950 W m −2 and a peak radiative cooling power of 104 W m −2 when solar intensity reached ≈910 W m −2 .…”

Section: Porous Materialsmentioning

confidence: 99%

“…For instance, Tian et al recently developed a facile but high-performance cooling materials with hydroxyapatite, Ca 10 (OH) 2 (PO 4 ) 6 fibers, which can self-assemble into bundles and form a porous network, resulting in high solar reflectance of 99%. [69] Moreover, the strong molecular vibrations of phosphate radical can provide high mid-infrared emissivity of ≈90%.…”

Section: Intrinsic Porous Structurementioning

confidence: 99%

Micro‐Nano Porous Structure for Efficient Daytime Radiative Sky Cooling

Liu

Tang

Jiang

et al. 2022

Adv Funct Materials

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CO 2 in 2050. [5] Due to the second law of thermodynamics, cooling is generally more challenging than heating. Conventional vapor-compression cooling not only results in excessive energy consumption, accelerating the depletion of fossil fuels, but also degrades the atmospheric ozone, leading to notorious environmental issues. Therefore, developing novel and pollutionfree cooling technology has become an urgent demand in the following decades.Radiative sky cooling (RSC) can harvest the coldness of the universe via the 8-13 µm atmospheric window without any pollution and energy consumption, which has witnessed great progress in the last few years. [6][7][8] Since the first demonstration of daytime radiative cooling via multilayer photonic structure by Fan and co-workers in 2014, this facile cooling technology has drawn worldwide attention. [9,10] With the joint efforts, RSC technology has achieved striking advances in building cooling, [4,11] photovoltaic cooling, [12][13][14] cryogenic cooling, [15,16] RSC driving thermoelectricity, [17][18][19] atmospheric water harvesting, [20,21] personal thermal management [3,22,23] and wearable devices. [24][25][26] For building cooling, the pioneering reports by Goldstein et al. and Zhao et al. have demonstrated that building-integrated RSC modules can provide continuous day-and-night cooling and can potentially save 32%-45% of the electricity consumption for cooling in summer. [4,11] For photovoltaic cooling, selective photonic cooler can lower the temperature of solar panels by over 5.7 K and afford the greater cooling

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Subambient daytime cooling enabled by hierarchically architected all-inorganic metapaper with enhanced thermal dissipation

Cited by 48 publications

References 41 publications

Machine Learning-Enabled Inverse Design of Radiative Cooling Film with On-Demand Transmissive Color

Machine Learning-Enabled Inverse Design of Radiative Cooling Film with On-Demand Transmissive Color

Flexible and Dual‐Sided Available Colored Films for Efficient Daytime Radiative Cooling

Micro‐Nano Porous Structure for Efficient Daytime Radiative Sky Cooling

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