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

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.

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

Atmosphere ◽  
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.

scholarly journals Theoretical and Experimental Study of Spectral Selectivity Surface for Both Solar Heating and Radiative Cooling

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Mingke Hu ◽  
Gang Pei ◽  
Lei Li ◽  
Renchun Zheng ◽  
Junfei Li ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Heating Surface ◽  
Solar Heating ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Relative Temperature ◽  
Composite Surface ◽  
Spectral Selectivity ◽  
Atmospheric Window ◽  
Inclination Angles

A spectral selectivity surface for both solar heating and radiative cooling was proposed. It has a high spectral absorptivity (emissivity) in the solar radiation band and atmospheric window band (i.e., 0.2~3 μm and 8~13 μm), as well as a low absorptivity (emissivity) in other bands aside from the solar radiation and atmospheric window wavelengths (i.e., 3~8 μm or above 13 μm). A type of composite surface sample was trial-manufactured combining titanium-based solar selective absorbing coating with polyethylene terephthalate (TPET). Sample tests showed that the TPET composite surface has clear spectral selectivity in the spectra of solar heating and radiation cooling wavelengths. The equilibrium temperatures of the TPET surface under different sky conditions or different inclination angles of surface were tested at both day and night. Numerical analysis and comparisons among the TPET composite surface and three other typical surfaces were also performed. These comparisons indicated that the TPET composite surface had a relative heat efficiency of 76.8% of that of the conventional solar heating surface and a relative temperature difference of 75.0% of that of the conventional radiative cooling surface, with little difference in cooling power.

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

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.

scholarly journals Highly effective photon-to-cooling thermal device

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yanpei Tian ◽  
Lijuan Qian ◽  
Xiaojie Liu ◽  
Alok Ghanekar ◽  
Gang Xiao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thermal Structure ◽  
Outer Space ◽  
Temperature Drop ◽  
Transparency Window ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Atmospheric Transparency ◽  
Cooling Method ◽  
Highly Effective

AbstractPhoton-to-cooling phenomenon relies on the atmospheric transparency window to dissipate heat from the earth into outer space, which is an energy-saving cooling technique. This work demonstrates a highly effective aluminized Polymethylpentene (PMP) thin-film thermal structure. The emissivity of aluminized PMP thin films matches well to the atmospheric transparency window so as to minimize parasitic heat losses. This photon-to-cooling structure yields a temperature drop of 8.5 K in comparison to the ambient temperature and a corresponding radiative cooling power of 193 W/m2 during a one-day cycle. The easy-to-manufacture feature of an aluminized PMP thin film makes it a practically scalable radiative cooling method.

Hierarchical-morphology metafabric for scalable passive daytime radiative cooling

Science ◽  
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.

scholarly journals Continuously variable emission for mechanical deformation induced radiative cooling

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.

scholarly journals A structural polymer for highly efficient all-day passive radiative cooling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tong Wang ◽  
Yi Wu ◽  
Lan Shi ◽  
Xinhua Hu ◽  
Min Chen ◽  
...  
Keyword(s):  
Low Cost ◽  
Outer Space ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Pmma Film ◽  
Thermal Emittance ◽  
Highly Efficient ◽  
Solar Reflectance ◽  
Solar Intensity ◽  
Porous Array

AbstractAll-day passive radiative cooling has recently attracted tremendous interest by reflecting sunlight and radiating heat to the ultracold outer space. While some progress has been made, it still remains big challenge in fabricating highly efficient and low-cost radiative coolers for all-day and all-climates. Herein, we report a hierarchically structured polymethyl methacrylate (PMMA) film with a micropore array combined with random nanopores for highly efficient day- and nighttime passive radiative cooling. This hierarchically porous array PMMA film exhibits sufficiently high solar reflectance (0.95) and superior longwave infrared thermal emittance (0.98) and realizes subambient cooling of ~8.2 °C during the night and ~6.0 °C to ~8.9 °C during midday with an average cooling power of ~85 W/m2 under solar intensity of ~900 W/m2, and promisingly ~5.5 °C even under solar intensity of ~930 W/m2 and relative humidity of ~64% in hot and moist climate. The micropores and nanopores in the polymer film play crucial roles in enhancing the solar reflectance and thermal emittance.

scholarly journals Multispectral camouflage for infrared, visible, lasers and microwave with radiative cooling

2020 ◽  
Author(s):  
Huanzheng Zhu ◽  
Qiang Li ◽  
Chenning Tao ◽  
Yu Hong ◽  
Ziquan Xu ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Input Power ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Long Wavelength ◽  
Military Equipment ◽  
Atmospheric Window ◽  
Visible Lasers ◽  
Ir Bands ◽  
Low Emittance

Abstract Interminable surveillance and reconnaissance through various sophisticated multispectral detectors present threats to military equipment and manpower. However, a combination of detectors operating in different wavelength bands (from hundreds of nanometers to centimeters) and based on different principles raises challenges to the conventional single-band camouflage devices. In this paper, multispectral camouflage is demonstrated for the visible, mid-infrared (MIR, 3-5 and 8-14 μm), lasers (1.55 and 10.6 μm) and microwave (8-12 GHz) bands with simultaneous efficient radiative cooling in the non-atmospheric window (5-8 μm). The device for multispectral camouflage consists of ZnS/Ge multilayer for wavelength selective emission and Cu-ITO-Cu metasurface for microwave absorption. In comparison with conventional broadband low emittance material (Cr), the IR camouflage performance of this device manifests 8.4/5.9 °C reduction of inner/surface temperature, and 53.4/13.0 % IR signal decrease in mid/long wavelength IR bands, at 2500 W∙m-2 input power density. Furthermore, we revealed that the natural convection in the atmosphere can be enhanced by radiation in the non-atmospheric window, which increases the total cooling power from 136 W∙m-2 to 252 W∙m-2 at 150 °C surface temperature. This work may introduce the opportunities for multispectral manipulation, infrared signal processing, thermal management, and energy-efficient applications.

Radiative Cooling in Northern Europe Using a Roof Window

2010 ◽  
Author(s):  
Martin Fa¨lt ◽  
Ron Zevenhoven
Keyword(s):  
Greenhouse Gas ◽  
Heat Radiation ◽  
Weather Data ◽  
Northern Europe ◽  
Radiative Cooling ◽  
Air Masses ◽  
Thermal Insulator ◽  
Atmospheric Window ◽  
And Performance ◽  
Set Up

The design and performance of a triple glass window used as a roof component was analyzed in this paper. A mathematical model was set up for the component and weather data for the Finnish city Helsinki was used to assess its performance. This roof component would act as a passive radiative cooler during the summer and as a thermal insulator during the rest of the year. This versatile usage of the window component would thus decrease the need for traditional air-conditioning during summer and hence save electricity. The triple glass window would consist of one normal silica window and of two High Density Polyethylene (HPDE) windows. The space between the three windows would contain a (pressurized) greenhouse gas that would act as the heat carrier in this system. The heat would be transferred in to the system to the gas by heat radiation, conduction and natural convection through the window facing the room. This heated gas would then rise to the upper vacant space due to a decrease in the gases density caused by the heating. In the upper vacant part, the gas would then be cooled by radiative cooling through the HDPE, and the atmospheric window with colder air masses in the upper atmosphere. When, the greenhouse gas would have cooled down its density would increase and the gas would drop to the lower part of the window component. During times when no cooling would be needed the connection between the two vacant spaces would be cut, thus changing the roof components’ task from a passive radiative cooler to a thermal insulator. The heating of the space due to sunshine is of course evident and lower temperatures would be achieved if no window at all be used, but for places were roof windows are built this component would offer a viable alternative. This paper is a continuation to the paper by Zevenhoven and Fa¨lt submitted to this conference (1).

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

Buildings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 168 ◽  
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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