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

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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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 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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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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Spectral (direct) solar irradiance at Pune

MAUSAM ◽

10.54302/mausam.v49i4.3660 ◽

2021 ◽

Vol 49 (4) ◽

pp. 487-492

Author(s):

R. D. VASHISTHA ◽

R. MADAN ◽

S. K. SRIVASTAV

Keyword(s):

Large Scale ◽

Aerosol Particles ◽

Solar Spectrum ◽

Solar Irradiation ◽

Atmospheric Conditions ◽

Land Use Patterns ◽

Use Patterns ◽

Yellow Orange ◽

The Individual ◽

The Comparative Study

Direct Solar Irradiation (DSI) measurements are made with pyrheliometers. When used with selected filters, the spectral distribution can be worked out. Measurements at Pune indicate that large scale attenuation takes place in blue-green region of solar spectrum likely due to aerosol particles injected by industrial advancement over the region. consequent rapid urbanisation and resultant changed land-use patterns. Values show evidences on the role played by moisture field on the transmission characteristics of the Pune skies. The afternoon irradiances are seen to be generally higher than the forenoon values. However, IR and yellow-orange wavelengths have higher irradiances in the forenoons during the pre-monsoon months and occasionally even in March. Over a year 774 Wm-2 of irradiance can be expected on any cloudless occasion around noon time, the individual spectral values vary depending on the actual sky and atmospheric conditions. From the comparative study of the irradiances in the different spectral regions, inferences could be drawn on the changes that take place in the size distribution of aerosol particles during a day.

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Continuously variable emission for mechanical deformation induced radiative cooling

Communications Materials ◽

10.1038/s43246-020-00098-8 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Xiaojie Liu ◽

Yanpei Tian ◽

Fangqi Chen ◽

Alok Ghanekar ◽

Mauro Antezza ◽

...

Keyword(s):

Effective Medium Theory ◽

Outer Space ◽

Emission Spectra ◽

Radiative Cooling ◽

Medium Theory ◽

Dynamic Tuning ◽

The Past ◽

Atmospheric Window ◽

Human Need ◽

Different Strains

AbstractPassive 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.

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

Buildings ◽

10.3390/buildings8120168 ◽

2018 ◽

Vol 8 (12) ◽

pp. 168 ◽

Cited By ~ 27

Author(s):

Mattheos Santamouris ◽

Jie Feng

Keyword(s):

Thin Film ◽

Thermal Performance ◽

Recent Progress ◽

Solar Spectrum ◽

Radiative Cooling ◽

The Sun ◽

Air Conditioner ◽

Photonic Structures ◽

Atmospheric Window ◽

Ambient Surface

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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Nanoparticle embedded double-layer coating for daytime radiative cooling

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2016.08.009 ◽

2017 ◽

Vol 104 ◽

pp. 890-896 ◽

Cited By ~ 103

Author(s):

Zhifeng Huang ◽

Xiulin Ruan

Keyword(s):

Double Layer ◽

Radiative Cooling ◽

Layer Coating

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Biologically Inspired Scalable-Manufactured Dual-layer Coating with a Hierarchical Micropattern for Highly Efficient Passive Radiative Cooling and Robust Superhydrophobicity

ACS Applied Materials & Interfaces ◽

10.1021/acsami.1c05651 ◽

2021 ◽

Author(s):

Shuqi Wang ◽

Yaming Wang ◽

Yongchun Zou ◽

Guoliang Chen ◽

Jiahu Ouyang ◽

...

Keyword(s):

Radiative Cooling ◽

Biologically Inspired ◽

Highly Efficient ◽

Layer Coating

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Solar Thermochemical Hydrogen Production in the USA

Sustainability ◽

10.3390/su13147804 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7804

Author(s):

Christoph Falter ◽

Andreas Sizmann

Keyword(s):

Hydrogen Production ◽

Large Scale ◽

Low Cost ◽

The United States ◽

Solar Irradiation ◽

Transport Sector ◽

Fossil Energy ◽

The Us ◽

The Usa ◽

Solar Thermochemical

Hydrogen produced from renewable energy has the potential to decarbonize parts of the transport sector and many other industries. For a sustainable replacement of fossil energy carriers, both the environmental and economic performance of its production are important. Here, the solar thermochemical hydrogen pathway is characterized with a techno-economic and life-cycle analysis. Assuming a further increase of conversion efficiency and a reduction of investment costs, it is found that hydrogen can be produced in the United States of America at costs of 2.1–3.2 EUR/kg (2.4–3.6 USD/kg) at specific greenhouse gas emissions of 1.4 kg CO2-eq/kg. A geographical potential analysis shows that a maximum of 8.4 × 1011 kg per year can be produced, which corresponds to about twelve times the current global and about 80 times the current US hydrogen production. The best locations are found in the Southwest of the US, which have a high solar irradiation and short distances to the sea, which is beneficial for access to desalinated water. Unlike for petrochemical products, the transport of hydrogen could potentially present an obstacle in terms of cost and emissions under unfavorable circumstances. Given a large-scale deployment, low-cost transport seems, however, feasible.

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