scholarly journals Fabry–Perot resonance assisted dual-layer coating with enhanced wavelength-selective refection and emission for daytime radiative cooling

2021 ◽  
Vol 483 ◽  
pp. 126673
Author(s):  
Lei Wang ◽  
Zhiheng Zheng ◽  
Yuchun Gou ◽  
Wenwen Liang ◽  
Wei Yu
Keyword(s):  
Radiative Cooling ◽  
Fabry Perot ◽  
Layer Coating

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.

Fabry–Perot-resonator-coupled metal pattern metamaterial for infrared suppression and radiative cooling

2020 ◽  
Vol 59 (23) ◽  
pp. 6861
Author(s):  
Dachuan Liu ◽  
Yuanpei Xu ◽  
Yimin Xuan
Keyword(s):  
Radiative Cooling ◽  
Metal Pattern ◽  
Fabry Perot

scholarly journals Estimation of multi-layer coating efficiency for passive radiative cooling

2021 ◽  
Vol 5 (2) ◽  
pp. 37-46
Author(s):  
S. S. Jenblat ◽  
◽  
O. V. Volkova ◽  
Keyword(s):  
Mathematical Model ◽  
Optical Properties ◽  
Cooling System ◽  
Climatic Conditions ◽  
Cooling Power ◽  
Radiative Cooling ◽  
Cooling Systems ◽  
Coating Efficiency ◽  
Atmospheric Transmittance ◽  
Layer Coating

Passive radiative cooling is a promising direction in energy conservation and environmental protection. One of the ways to increase the efficiency of radiative cooling systems is the use of multi-layer coatings. In recent years, several novel materials with high emissivity have been proposed, which allow the creation of radiators that provide an average daily cooling power of approximately 100 W/m2 during daytime. Based on the developed mathematical model, the optical properties of the multi-layer coating for the radiative cooling system were evaluated by the Transfer Matrix Method and the effectiveness of radiative cooling was determined due to the use of the multi-layer coating in the climatic conditions of Syria (Latakia). The results of modeling the atmospheric transmittance in the summer months in Syria (Latakia) are presented. The developed mathematical model, methods for modeling atmospheric transmittance, calculating solar radiation, and evaluating the optical properties of multi-layer coating, allow determining an effective multi-layer coating for radiative cooling systems in any climatic conditions

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Diffraction de réseaux d'indice en cavité Fabry-Pérot

2000 ◽  
Vol 10 (PR8) ◽  
pp. Pr8-251
Author(s):  
L. Menez ◽  
I. Zaquine ◽  
A. Maruani ◽  
R. Frey
Keyword(s):  
Fabry Perot
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