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 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 Analysis of Sustainable Materials for Radiative Cooling Potential of Building Surfaces

2018 ◽  
Vol 10 (9) ◽  
pp. 3049 ◽  
Author(s):  
Roxana Family ◽  
M. Mengüç
Keyword(s):  
Heat Transfer ◽  
Emission Spectra ◽  
Spectral Emissivity ◽  
Volumetric Analysis ◽  
Solar Heating ◽  
Heat Transfer Analysis ◽  
Surface Phenomenon ◽  
Radiative Cooling ◽  
Atmospheric Window ◽  
Building Surfaces

The main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2–2 μm), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8–13 μm), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.

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.

scholarly journals Reflective and transparent cellulose-based passive radiative coolers

Cellulose ◽  
2021 ◽  
Author(s):  
Sampath Gamage ◽  
Debashree Banerjee ◽  
Md. Mehebub Alam ◽  
Tomas Hallberg ◽  
Christina Åkerlind ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Thermal Radiation ◽  
Solar Heating ◽  
Infrared Light ◽  
Radiative Cooling ◽  
Cellulose Derivatives ◽  
Solar Absorption ◽  
Thermal Emissivity ◽  
Cellulose Materials ◽  
Sun Light

AbstractRadiative cooling passively removes heat from objects via emission of thermal radiation to cold space. Suitable radiative cooling materials absorb infrared light while they avoid solar heating by either reflecting or transmitting solar radiation, depending on the application. Here, we demonstrate a reflective radiative cooler and a transparent radiative cooler solely based on cellulose derivatives manufactured via electrospinning and casting, respectively. By modifying the microstructure of cellulose materials, we control the solar light interaction from highly reflective (> 90%, porous structure) to highly transparent (≈ 90%, homogenous structure). Both cellulose materials show high thermal emissivity and minimal solar absorption, making them suitable for daytime radiative cooling. Used as coatings on silicon samples exposed to sun light at daytime, the reflective and transparent cellulose coolers could passively reduce sample temperatures by up to 15 °C and 5 °C, respectively.

scholarly journals Reflective and Transparent Cellulose-Based Passive Radiative Coolers

2021 ◽  
Author(s):  
Sampath Gamage ◽  
Md. Mehebub Alam ◽  
Tomas Hallberg ◽  
Chriatina Akerlind ◽  
Ayesha Sultana ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Thermal Radiation ◽  
Solar Heating ◽  
Infrared Light ◽  
Radiative Cooling ◽  
Cellulose Derivatives ◽  
Solar Absorption ◽  
Thermal Emissivity ◽  
Cellulose Materials ◽  
Sun Light

Abstract Radiative cooling passively removes heat from objects via emission of thermal radiation to cold space. Suitable radiative cooling materials absorb infrared light while they avoid solar heating by either reflecting or transmitting solar radiation, depending on the application. Here, we demonstrate a reflective radiative cooler and a transparent radiative cooler solely based on cellulose derivatives manufactured via electrospinning and casting, respectively. By modifying the microstructure of cellulose materials, we can control the solar light interaction from highly reflective (>90%, porous structure) to highly transparent (≈90%, homogenous structure). Both cellulose materials show strong thermal emissivity and minimal solar absorption, making them suitable for daytime radiative cooling. Used as coatings on silicon samples exposed to sun light at daytime, the reflective and transparent cellulose coolers could passively reduce sample temperatures by up to 32 °C and 15 °C, respectively.

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

2021 ◽  
Vol 12 (1) ◽  
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

AbstractInterminable 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 a ZnS/Ge multilayer for wavelength selective emission and a 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 reveal 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.

scholarly journals Adaptive covers for combined radiative cooling and solar heating. A review of existing technology and materials

2021 ◽  
Vol 230 ◽  
pp. 111275
Author(s):  
Roger Vilà ◽  
Ingrid Martorell ◽  
Marc Medrano ◽  
Albert Castell
Keyword(s):  
Solar Heating ◽  
Radiative Cooling

scholarly journals Hybrid concentrated radiative cooling and solar heating in a single system

2021 ◽  
Vol 2 (2) ◽  
pp. 100338
Author(s):  
Lyu Zhou ◽  
Haomin Song ◽  
Nan Zhang ◽  
Jacob Rada ◽  
Matthew Singer ◽  
...  
Keyword(s):  
Solar Heating ◽  
Radiative Cooling ◽  
Single System

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 Evaluation and Recommendations for Improving the Accuracy of an Inexpensive Water Temperature Logger

2013 ◽  
Vol 30 (7) ◽  
pp. 1576-1582 ◽  
Author(s):  
S. J. Lentz ◽  
J. H. Churchill ◽  
C. Marquette ◽  
J. Smith
Keyword(s):  
Surface Layer ◽  
Solar Radiation ◽  
Water Temperature ◽  
Solar Heating ◽  
Bias Error ◽  
Mean Square ◽  
Temperature Logger ◽  
Accurate Temperature ◽  
Rms Error ◽  
Rms Errors

Abstract Onset's HOBO U22 Water Temp Pros are small, reliable, relatively inexpensive, self-contained temperature loggers that are widely used in studies of oceans, lakes, and streams. An in-house temperature bath calibration of 158 Temp Pros indicated root-mean-square (RMS) errors ranging from 0.01° to 0.14°C, with one value of 0.23°C, consistent with the factory specifications. Application of a quadratic calibration correction substantially reduced the RMS error to less than 0.009°C in all cases. The primary correction was a bias error typically between −0.1° and 0.15°C. Comparison of water temperature measurements from Temp Pros and more accurate temperature loggers during two oceanographic studies indicates that calibrated Temp Pros have an RMS error of ~0.02°C throughout the water column at night and beneath the surface layer influenced by penetrating solar radiation during the day. Larger RMS errors (up to 0.08°C) are observed near the surface during the day due to solar heating of the black Temp Pro housing. Errors due to solar heating are significantly reduced by wrapping the housing with white electrical tape.

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