Recent Progress in Daytime Radiative Cooling: Is It the Air Conditioner of the Future?

Radiative cooling is a well-researched area. For many years, surfaces relying on radiative cooling failed to exhibit a sub-ambient surface temperature under the sun because of the limited reflectance in the solar spectrum and the reduced absorptivity in the atmospheric window. The recent impressive developments in photonic nanoscience permitted to produce photonic structures exhibiting surface temperatures much below the ambient temperature. This paper aims to present and analyze the main recent achievements concerning daytime radiative cooling technologies. While the conventional radiative systems are briefly presented, the emphasis is given on the various photonic radiative structures and mainly the planar thin film radiators, metamaterials, 2 and 3D photonic structures, polymeric photonic technologies, and passive radiators under the form of a paint. The composition of each structure, as well as its experimental or simulated thermal performance, is reported in detail. The main limitations and constraints of the photonic radiative systems, the proposed technological solutions, and the prospects are presented and discussed.

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Performance simulation of polymer-based nanoparticle and void dispersed photonic structures for radiative cooling

Scientific Reports ◽

10.1038/s41598-020-80490-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jay Prakash Bijarniya ◽

Jahar Sarkar ◽

Pralay Maiti

Keyword(s):

Fdtd Method ◽

Solar Spectrum ◽

Thermal Infrared ◽

Performance Estimation ◽

Radiative Cooling ◽

Slab Thickness ◽

Slight Variation ◽

Performance Simulation ◽

Atmospheric Window ◽

Substrate Independent

AbstractPassive radiative cooling is an emerging field and needs further development of material. Hence, the computational approach needs to establish for effective metamaterial design before fabrication. The finite difference time domain (FDTD) method is a promising numerical strategy to study electromagnetic interaction with the material. Here, we simulate using the FDTD method and report the behavior of various nanoparticles (SiO2, TiO2, Si3N4) and void dispersed polymers for the solar and thermal infrared spectrums. We propose the algorithm to simulate the surface emissive properties of various material nanostructures in both solar and thermal infrared spectrums, followed by cooling performance estimation. It is indeed found out that staggered and randomly distributed nanoparticle reflects efficiently in the solar radiation spectrum, become highly reflective for thin slab and emits efficiently in the atmospheric window (8–13 µm) over the parallel arrangement with slight variation. Higher slab thickness and concentration yield better reflectivity in the solar spectrum. SiO2-nanopores in a polymer, Si3N4 and TiO2 with/without voids in polymer efficiently achieve above 97% reflection in the solar spectrum and exhibits substrate independent radiative cooling properties. SiO2 and polymer combination alone is unable to reflect as desired in the solar spectrum and need a highly reflective substrate like silver.

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Hierarchical-morphology metafabric for scalable passive daytime radiative cooling

Science ◽

10.1126/science.abi5484 ◽

2021 ◽

pp. eabi5484

Author(s):

Shaoning Zeng ◽

Sijie Pian ◽

Minyu Su ◽

Zhuning Wang ◽

Maoqi Wu ◽

...

Keyword(s):

High Performance ◽

Large Scale ◽

Global Climate ◽

Solar Spectrum ◽

Radiative Cooling ◽

Practical Application ◽

Atmospheric Window ◽

The Cost ◽

Hierarchical Morphology ◽

Cooling Ability

Incorporating passive radiative cooling structures into personal thermal management technologies could effectively defend human against the intensifying global climate change. We show that large scale woven metafabrics can provide high emissivity (94.5%) in the atmospheric window and reflectivity (92.4%) in the solar spectrum because the hierarchical-morphology design of the randomly dispersed scatterers throughout the metafabric. Through scalable industrial textile manufacturing routes, our metafabrics exhibit excellent mechanical strength, waterproofness, and breathability for commercial clothing while maintaining efficient radiative cooling ability. Practical application tests demonstrated the human body covered by our metafabric could be cooled down ~4.8°C lower than that covered by commercial cotton fabric. The cost-effectiveness and high-performance of our metafabrics present great advantages for intelligent garments, smart textiles, and passive radiative cooling applications.

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Simple Double-Layer Coating for Efficient Daytime and Nighttime Radiative Cooling

Atmosphere ◽

10.3390/atmos12091198 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1198

Author(s):

Mourad Benlattar ◽

Issam Ibourk ◽

Rahma Adhiri

Keyword(s):

Double Layer ◽

Large Scale ◽

Outer Space ◽

Solar Spectrum ◽

Bottom Layer ◽

Solar Irradiation ◽

Radiative Cooling ◽

Atmospheric Window ◽

Thermal Emitters ◽

Layer Coating

The passive radiative cooling approach refers to the physical process that pumps heat into outer space via the atmospheric window (8–13 μm) without energy input. The ability to continuously adjust the emissivity of thermal emitters in the sky window while maintaining high reflectivity in the solar spectrum remains a challenge. In order to achieve this task, a novel design referred to as double-layer nanoparticle-based coating is proposed. Our proposed emitter is appropriate for both high solar reflection and strong mid-infrared emissivity. The bottom and top layers are Al2O3 embedded with Ni nanoparticles and a super-hydrophilic TiO2-SiO2 layer. The bottom layer is designed to achieve high emissivity in “the atmospheric transparency window”. The top layer is designed to block solar illumination and to favor an enhanced cleanability of the coated design. Our double-layer coating as an optical solar reflector has excellent solar irradiation ( and is strongly emissive (0.97) across the “full sky window” at room temperature. Furthermore, a detailed numerical energy study has been performed, evaluating the temperature reduction and the radiative cooling performance under different conditions. The proposed simple coating can be used as an efficient radiative cooler on a large scale for energy conservation and thermoelectric devices.

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All-day uninterrupted power generator: Harvesting energy from the sun and cold space

10.21203/rs.3.rs-832470/v1 ◽

2021 ◽

Author(s):

Shuai Zhang ◽

Zhenhua Wu ◽

Zekun Liu ◽

Erzhen Mu ◽

Yang Liu ◽

...

Keyword(s):

Power Generation ◽

Energy Utilization ◽

Small Scale ◽

Radiative Cooling ◽

The Sun ◽

Power Generator ◽

Solar Absorber ◽

Atmospheric Window ◽

Power Generation System ◽

Continuous Power

Abstract Harvesting energy from the environment to generate electricity is attracting tremendous interest to enrich the forms of energy utilization, reduce greenhouse gas emissions and alleviate the global energy crisis1,2. However, achieving an unlimited and uninterrupted all-day power generation from the ambient energy is still challenging3. Herein, we demonstrate a passive power device to harvest energy from the sun and cold space based on micro-fabricated thermoelectric generator (TEG) integrated with solar absorber (SA) and radiative cooling emitter (RCE) to realize continuous power generation form the ambient. The ultrathin TEG, that with a sensitivity of 10− 4 K achieved output power density of 960 W/m3 while heated to 80°C at room temperature. The solar absorber (SA) performs photothermal conversion to heat the TEG in the daytime4, while the radiative cooling emitter (RCE) radiates the heat to the cold space through the atmospheric window to cool the TEG all the clear day5,6. Our strategy provides a renewable and sustainable thermodynamic resource to build a temperature difference over TEG for all-day uninterrupted power generation for wide application scenarios. This is the first proof-of-principle uninterrupted power generation system independent of time on a small scale, and opportunities exist for environmental energy harvesting and electricity generation beyond traditional technologies.

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Simple PDMS/AIN emitter as a passive daytime radiative cooling design

10.21203/rs.3.rs-733212/v1 ◽

2021 ◽

Author(s):

Mabchour ◽

benlattar mourad

Keyword(s):

Outer Space ◽

Solar Spectrum ◽

Ambient Air ◽

Heat Radiation ◽

Cooling Power ◽

Radiative Cooling ◽

Spectral Selectivity ◽

Solar Energy Harvesting ◽

Atmospheric Window ◽

Cooling Design

Abstract Radiative cooling is a passive cooling purpose where a surface naturally cools by radiating the mid-infrared heat radiation to the cold outer space through the atmospheric window . Daytime passive radiative cooling technologies can be simply provided by using a multi-layer design that emits strongly in the transparency atmospheric window, while presents high reflectance in the solar spectrum . In this study, we propose a polydimethylsiloxane foil ) coated aluminum nitride (AIN) deposed onto silver (Ag) coated glass as a radiative cooler for enhancing both daytime and nighttime radiative cooling performances. The spectral selectivity of the proposed device was obtained using matrix method. Numerical results show that our proposed design can reflect more than 96 % in the solar spectrum, while its average emissivity in the atmospheric window can reach more than 90 %.In the absence of wind speed, the proposed device can achieve a net cooling power of under direct sunlight, cooling to a below the ambient air temperature. At nighttime, the proposed device temperature can drop by below the ambient, leading to a net cooling power of . Therefore, the proposed radiative design can fundamentally enable new methods for exploiting solar energy harvesting and energy conservation.

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Recent Progress in Design of Plasmonic Thin-Film Solar Cells with Enhanced Efficiency

Recent Patents on Materials Science ◽

10.2174/1874464811205020166 ◽

2012 ◽

Vol 5 (2) ◽

pp. 166-172 ◽

Cited By ~ 1

Author(s):

Lifang Si ◽

Teng Qiu ◽

Wenjun Zhang ◽

Paul K. Chu

Keyword(s):

Thin Film ◽

Solar Cells ◽

Recent Progress ◽

Thin Film Solar Cells

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Optical and structural properties of thin film amorphous oxides for photonic structures

2020 IEEE Photonics Conference (IPC) ◽

10.1109/ipc47351.2020.9252557 ◽

2020 ◽

Author(s):

Kestutis Juskevicius ◽

Emmett Randel ◽

Le Yang ◽

Mariana Fazio ◽

Aaron Davenport ◽

...

Keyword(s):

Thin Film ◽

Structural Properties ◽

Amorphous Oxides ◽

Photonic Structures

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Enhancing the Efficiency of GaSb Photovoltaic Cell Using Thin-Film Multiscale Haze and Radiative Cooling

ACS Applied Energy Materials ◽

10.1021/acsaem.1c01536 ◽

2021 ◽

Author(s):

Prince Gupta ◽

Yeonhong Kim ◽

Jonghyeok Im ◽

Gumin Kang ◽

Augustine M. Urbas ◽

...

Keyword(s):

Thin Film ◽

Photovoltaic Cell ◽

Radiative Cooling

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Analysis of a Hybrid PV/T Concept Based on Wavelength Selective Films

ASME 2013 7th International Conference on Energy Sustainability ◽

10.1115/es2013-18011 ◽

2013 ◽

Cited By ~ 5

Author(s):

Tejas U. Ulavi ◽

Jane H. Davidson ◽

Tim Hebrink

Keyword(s):

Thin Film ◽

Monte Carlo ◽

Total Energy ◽

Ray Tracing ◽

Solar Spectrum ◽

Photovoltaic Module ◽

Optical Performance ◽

Technical Performance ◽

Compound Parabolic Concentrator ◽

Pv Modules

The technical performance of a non-tracking hybrid PV/T concept that uses a wavelength selective film is modeled. The wavelength selective film is coupled with a compound parabolic concentrator to reflect and concentrate the infrared portion of the solar spectrum onto a tubular absorber while transmitting the visible portion of the spectrum to an underlying thin-film photovoltaic module. The optical performance of the CPC/selective film is obtained through Monte Carlo Ray-Tracing. The CPC geometry is optimized for maximum total energy generation for a roof-top application. Applied to a rooftop in Phoenix, Arizona USA, the hybrid PV/T provides 20% more energy compared to a system of the same area with independent solar thermal and PV modules, but the increase is achieved at the expense of a decrease in the electrical efficiency from 8.8% to 5.8%.

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