Water collection from fog has received much attention to meet the challenges of scarcity of clean drinking water in desert and arid regions. Currently, solar‐thermal technology is being used as an efficient, sustainable, and low‐cost method for water desalination to produce clean water. To collect the clean water, in recent years, most researchers have designed the structure of water collection surfaces. However, the heat released during the liquefaction process of droplets has an adverse effect on the condensation of droplets, and thus affecting the water collection efficiency. Here, in order to improve water collection efficiency, a radiative cooling layer is introduced on the back of the collection surface to dissipate the heat released during droplet liquefaction. The radiative cooling layer, consisting of poly(vinylidene fluoride‐co‐hexafluoropropene) embedded with SiO2 and CaMoO4 nanoparticles, can theoretically cool 18.1 °C below the ambient temperature in the daytime. With the addition of cooling coating on the back of the water collection surface, the water harvesting efficiency can be increased by 43–52%. The developed water harvesting device may provide a new pathway to the efficient collection of fresh water.
Energy consumption during cooling and heating poses a
great threat
to the development of society. Thermal regulation, as switchable cooling
and heating in a single platform, is therefore urgently demanded.
Herein, a switchable multifunctional device integrating heating, cooling,
and latent energy storage was proposed for temperature regulation
and window energy saving for buildings. A radiative cooling (RC) emitter,
a phase-change (PC) membrane, and a solar-heating (SH) film were connected
layer by layer to form a sandwich structure. The RC emitter exhibited
selective infrared emission (emissivity in the atmospheric window:
0.81, emissivity outside the atmospheric window: 0.39) and a high
solar reflectance (0.92). Meanwhile, the SH film had a high solar
absorptivity (0.90). More importantly, both the RC emitter and the
SH film displayed excellent wear resistance and UV resistance. The
PC layer can control the temperature at a steady state under dynamic
weather conditions, which could be verified by indoor and outdoor
measurements. The thermal regulation performance of the multifunctional
device was also verified by outdoor measurements. The temperature
difference between the RC and SH models of the multifunctional device
could reach up to 25 °C. The as-constructed switchable multifunctional
device is a promising candidate for alleviating the cooling and heating
energy consumption and realizing energy saving for windows.
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