Numerical Study of High Emissivity Metamaterials for Radiative Cooling Application

Abstract

In this work, disc metamaterials emitter was designed from silver and titanium dioxide by using COMSOL Multiphysics software for radiative cooling application. We have enhanced the broadband emission and high radiative cooling power by optimizing the geometric parameters such as radius of disc, thickness of dielectric and the width of the unit cell, while the parameters such as height of disc and the thickness of ground metal were fixed. In the calculation part, we considered temperature changes caused by atmospheric and surface radiation. The numerical simulation results showed that the designed metamaterial emitter had an average emissivity of 0.895 (89.5 %) within the atmospheric transparency window, which ranged from 8 - 13 µm. Eventually, our designed metamaterial emitter presents the potential to achieve a radiative cooling power of 200.4 W/m2 at ambient temperature (300 K) and yields a potential to reach an equilibrium temperature of 268.25 K. Even the designed metamaterial emitter holds the potential of cooling down 31.75 °C below the ambient temperature. Over all, in this work, selective metamaterial emitter had high radiative cooling power performance at ambient temperature. Based on our research work, such metamaterial emitters had the potential to emerge as a key element for the realization of energy-efficient radiative cooling devices. Therefore, this work further promotes the development of metal dielectric-metal based passive radiative coolers.