scholarly journals Accelerating vapor condensation with daytime radiative cooling

2019 ◽  
Author(s):  
Ming Zhou ◽  
Haomin Song ◽  
Xingyu Xu ◽  
Alireza Shahsafi ◽  
Zhenyang Xia ◽  
...  
Keyword(s):  
Vapor Condensation ◽  
Radiative Cooling

scholarly journals Vapor condensation with daytime radiative cooling

2021 ◽  
Vol 118 (14) ◽  
pp. e2019292118
Author(s):  
Ming Zhou ◽  
Haomin Song ◽  
Xingyu Xu ◽  
Alireza Shahsafi ◽  
Yurui Qu ◽  
...  
Keyword(s):  
Air Temperature ◽  
Liquid Water ◽  
Infrared Radiation ◽  
Ambient Air ◽  
Vapor Condensation ◽  
Passive Cooling ◽  
Radiative Cooling ◽  
Direct Sunlight ◽  
Produce Water ◽  
Extraction And Purification

A radiative vapor condenser sheds heat in the form of infrared radiation and cools itself to below the ambient air temperature to produce liquid water from vapor. This effect has been known for centuries, and is exploited by some insects to survive in dry deserts. Humans have also been using radiative condensation for dew collection. However, all existing radiative vapor condensers must operate during the nighttime. Here, we develop daytime radiative condensers that continue to operate 24 h a day. These daytime radiative condensers can produce water from vapor under direct sunlight, without active consumption of energy. Combined with traditional passive cooling via convection and conduction, radiative cooling can substantially increase the performance of passive vapor condensation, which can be used for passive water extraction and purification technologies.

TEM study of amorphization of Cu and Ti foils by cold-rolling

1990 ◽  
Vol 48 (4) ◽  
pp. 146-147
Author(s):  
W. A. Chiou ◽  
N. L. Jeon ◽  
Genbao Xu ◽  
M. Meshii
Keyword(s):  
Solid State ◽  
Cold Rolling ◽  
High Energy ◽  
Rapid Quenching ◽  
Vapor Condensation ◽  
Metallic Alloys ◽  
Solid State Reactions ◽  
High Energy Particle ◽  
Amorphous Metallic Alloys ◽  
Thin Foils

For many years amorphous metallic alloys have been prepared by rapid quenching techniques such as vapor condensation or melt quenching. Recently, solid-state reactions have shown to be an alternative for synthesizing amorphous metallic alloys. While solid-state amorphization by ball milling and high energy particle irradiation have been investigated extensively, the growth of amorphous phase by cold-rolling has been limited. This paper presents a morphological and structural study of amorphization of Cu and Ti foils by rolling.Samples of high purity Cu (99.999%) and Ti (99.99%) foils with a thickness of 0.025 mm were used as starting materials. These thin foils were cut to 5 cm (w) × 10 cm (1), and the surface was cleaned with acetone. A total of twenty alternatively stacked Cu and Ti foils were then rolled. Composite layers following each rolling pass were cleaned with acetone, cut into half and stacked together, and then rolled again.

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.

Cellulose-Based Hybrid Structural Material for Radiative Cooling

Nano Letters ◽  
2020 ◽  
Author(s):  
Yipeng Chen ◽  
Baokang Dang ◽  
Jinzhou Fu ◽  
Chao Wang ◽  
Caicai Li ◽  
...  
Keyword(s):  
Structural Material ◽  
Radiative Cooling
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