Double-layer nanoparticle-based coatings for efficient terrestrial radiative cooling

Bao, Hua; Chen, Yan; Wang, Boxiang; Fang, Xing; Zhao, Chang; Ruan, Xiulin

doi:10.1016/j.solmat.2017.04.020

Cited by 380 publications

(170 citation statements)

References 30 publications

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“…In Equation , P nonrad is nonradiative heating power got by the coating from the surrounding media, which can be defined as:

P_{nonrad} = q (T_{a} - T_{r})

here, q = q conduct + q convection is combined nonradiative heat coefficient taking root in the conductive and convective heat exchange of the coating with the surrounding air. From previous studies, we can see that q varies from 0 to 6.9 W m −2 K −1 with the change of environment and testing equipment …”

Section: Resultsmentioning

confidence: 89%

A Pragmatic Device Based on a Double‐Sided Functional Structure for Efficient Water Harvesting

Chen

Tao

et al. 2020

Global Challenges

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Water collection from fog has received much attention to meet the challenges of scarcity of clean drinking water in desert and arid regions. Currently, solar‐thermal technology is being used as an efficient, sustainable, and low‐cost method for water desalination to produce clean water. To collect the clean water, in recent years, most researchers have designed the structure of water collection surfaces. However, the heat released during the liquefaction process of droplets has an adverse effect on the condensation of droplets, and thus affecting the water collection efficiency. Here, in order to improve water collection efficiency, a radiative cooling layer is introduced on the back of the collection surface to dissipate the heat released during droplet liquefaction. The radiative cooling layer, consisting of poly(vinylidene fluoride‐co‐hexafluoropropene) embedded with SiO2 and CaMoO4 nanoparticles, can theoretically cool 18.1 °C below the ambient temperature in the daytime. With the addition of cooling coating on the back of the water collection surface, the water harvesting efficiency can be increased by 43–52%. The developed water harvesting device may provide a new pathway to the efficient collection of fresh water.

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“…In Equation , P nonrad is nonradiative heating power got by the coating from the surrounding media, which can be defined as:

P_{nonrad} = q (T_{a} - T_{r})

Section: Resultsmentioning

confidence: 89%

A Pragmatic Device Based on a Double‐Sided Functional Structure for Efficient Water Harvesting

Chen

Tao

et al. 2020

Global Challenges

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“…Gentle et al [63] conducted research consisting of a top layer of a mixture of SiC and SiO 2 , selected for their emissivity in the atmospheric window and a bottom layer made up of an Al plate to reflect solar radiation (Figure 4a). Bao et al [7] showed that by using densely packed TiO 2 particles on top of densely packed SiC or SiO 2 particles, all on an Al substrate can be used for radiative cooling purposes (Figure 4b). This design was able to produce an 8 • C reduction below the ambient temperature in a region with high humidity.…”

Section: Metamaterial-based Radiative Cooling Using Random Particlesmentioning

confidence: 99%

“…Various nighttime radiative cooling research has been reported by constructing selective emitters in the atmospheric transparency window [4][5][6] but the same techniques are inefficient during the daytime under strong sunlight. Daytime radiative cooling requires the additional condition of reflecting the entire solar spectrum (0.3-3 µm), while maintaining enough thermal radiation in the atmospheric window ( Figure 1a) [7][8][9]. The biggest hurdle is that the absorption of solar energy usually far exceeds the possible thermal radiative power [9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

Lee

Badloe

et al. 2018

Energies

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In the light of the ever increasing dangers of global warming, the efforts to reduce energy consumption by radiative cooling techniques have been designed, but are inefficient under strong sunlight during the daytime. With the advent of metamaterials and their selective control over optical properties, radiative cooling under direct sunlight is now possible. The key principles of metamaterial-based radiative cooling are: almost perfect reflection in the visible and near-infrared spectrum (0.3–3 µm) and high thermal emission in the infrared atmospheric window region (8–13 µm). Based on these two basic principles, studies have been conducted using various materials and structures to find the most efficient radiative cooling system. In this review, we analyze the materials and structures being used for radiative cooling, and suggest the future perspectives as a substitute in the current cooling industry.

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“…In optics and photonics, harnessing the interaction between light and disordered photonic structures recently inspires the rapid and amazing development of the field of "disordered photonics" [10,11], in which focusing [12,13] and imaging [14] through some seemingly scrambled media were successfully demonstrated. Moreover, enormous applications can be achieved by using disordered media with engineered micro/nano-structures, such as spontaneous emission control [15], random lasers [16][17][18] and radiative cooling [19][20][21], etc.…”

Section: Introductionmentioning

confidence: 99%

Near-resonant light transmission in two-dimensional dense cold atomic media with short-range positional correlations

Wang

Zhao

2020

J. Opt. Soc. Am. B

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Light propagation in disordered media is a fundamental and important problem in optics and photonics. In particular, engineering light-matter interaction in disordered cold atomic ensembles is one of the central topics in modern quantum and atomic optics. The collective response of dense atomic gases under light excitation, which crucially depends on the spatial distribution of atoms and the geometry of the ensemble, has important impacts on quantum technologies like quantum sensors, atomic clocks and quantum information storage.Here we analyze near-resonant light transmission in two-dimensional dense ultracold atomic ensembles with short-range positional correlations. Based on the coupled-dipole simulations under different atom number densities and correlation lengths, we show that the collective effects are strongly influenced by those positional correlations, manifested as significant shifts and broadening or narrowing of transmission resonance lines. The results show that mean-field theories like Lorentz-Lorenz relation are not capable of describing such collective effects. We further investigate the statistical distribution of eigenstates, which are significantly affected by the interplay between dipole-dipole interactions and position correlations. This work can provide profound implications on collective and cooperative effects in cold atomic ensembles as well as the study of mesoscopic physics concerning light transport in strongly scattering disordered media. simplest hard-sphere-type correlation which exists in densely packed hard spheres [32] can usually increase the transport mean free path of light [33,34]. Screened Coulomb potential induced positional correlations in nanoparticle colloidal suspensions were found to induce strongly negative asymmetry factor [35,36]. Recently, some unexpected optical properties like optical transparency [37], enhanced absorption [38] and isotropic photonic band gaps [39][40][41][42] were discovered in 2D and 3D disordered media with certain structural correlations, e.g., the stealthy hyperuniform media. Therefore, structural correlations offer a great opportunity for tailoring the optical properties of disordered materials, with promising applications like structural coloration [43,44], bright white paints [45] and solar energy harvesting [38,[46][47][48][49], etc.Despite these fascinating advancements, however, it is still not fully understood how structural correlations affect optical properties of disordered media, even for an ideally simple system composed of randomly distributed spherical scatterers [45,[50][51][52][53]. In particular, the interplay between structural correlations and near-field as well as far-field electromagnetic interactions among scatterers is still not very clear [50,51,54], especially near single scatterer internal resonances (like Mie resonances for dielectric nanoparticles) at high packing density [55][56][57][58][59].On the other hand, the last three decades have witnessed the rapid development of laser cooling and trapping of atoms to r...

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Double-layer nanoparticle-based coatings for efficient terrestrial radiative cooling

Cited by 380 publications

References 30 publications

A Pragmatic Device Based on a Double‐Sided Functional Structure for Efficient Water Harvesting

A Pragmatic Device Based on a Double‐Sided Functional Structure for Efficient Water Harvesting

Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

Near-resonant light transmission in two-dimensional dense cold atomic media with short-range positional correlations

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