Realization of an Efficient Radiative Cooling Emitter with Only Double Layer Inorganic Sio2 and Tio2 Metamaterial

Abstract

A novel double-layer thermal emitter consisting of only inorganic SiO2 and TiO2 metamaterials is proposed and numerically investigated. It can achieve ultrahigh absorption of 96.42% and 92.97% in both the first and second atmospheric transparency window to realize efficient radiative cooling. On the premise of obtaining high absorption, a comparative study on the design with and without the metal substrate has been conducted, verifying our simple design can be adopted to abandon the metal substrate. Meanwhile, such high emissivity even persists under different incident angles, air mass and water vapor column. A net cooling power of 164.39 W/m2 is achieved with the influence of convection coefficients. Finally, we establish a steady heat balance system to mimic the thermal emitter and obtain an average temperature drop of 9.6°C with an iterative method. Therefore, our design with excellent cooling capacity may provide a new guidance in the application of radiative cooling device.

Keywords: radiative cooling, Metamaterials, atmospheric window, emitter