passive radiative cooling

 

Radiative cooling

$${\mathrm{Eq.\; (1)}}^{}$$

$${\mathrm{Pcool}}^{}\left(T\right)=P_{\mathrm{rad}}\left(T\right)-P_{\mathrm{atm}}\left(T_{\mathrm{amb}}\right),$$

cooling power $P_{\text{cool}}$

where $P_{\mathrm{rad}}\left(T\right)$ and $P_{\mathrm{atm}}\left(T_{\mathrm{amb}}\right)$ are the thermal emission of the radiative cooler and thermal atmospheric radiations with the operating temperature $T$ and $T_{\mathrm{amb}}$

it appears to be highly transparent from 8 to $13\mu m$. One more sky window also appears between 16 and $23\mu m$. Due to its weak transmittance

 

a cooling device itself can be designed that possesses the capability to serve as both solar reflector and IR radiator simultaneously

Design Principle of Dielectric Reflectors

dielectric structure with nine layers of an alternating stack of polystyrene/tellurium materials and reported an ODR over the wavelength range from 10 to $15\mu m$.

                                                    Gallium antimonide (GaSb)

(GaSb)as high index medium

${\mathrm{SiO}}_2$ (as low-index medium)

net cooling power of around $100{W/m}^2$ at environmental temperature. They experimentally demonstrated a temperature reduction of 4.9°C below the ambient under direct sunlight

 Fig. 7(f)] and successfully demonstrated radiative cooling to 11°C below the environmental temperature.

further info ? cleck hear

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