Hybrid concentrated radiative cooling and solar heating in a single system

Abstract

Radiative cooling is an emerging sustainable technology that does not require electricity to function. However, to realize sub-ambient cooling, the effects of the undesired incident solar energy must be minimized. Considering an ideal blackbody radiator at 300 K, the maximum cooling power density is ∼160 W/m 2 . Here, we report an architecture capable of overcoming this challenge by using two spectrally selective mirrors to simultaneously absorb the incident sunlight and re-direct the thermal emission from a vertically aligned emitter. With this configuration, both sides of the vertical emitter can be used together to realize a measured local cooling power density of over 270 W/m 2 in a controlled laboratory environment. Under standard atmospheric pressure, we realized cooling that was 14°C below the ambient temperature in the laboratory environment and a more than 12°C temperature reduction in outdoor testing. A double-sided architecture couples thermal radiation from both sides of the emitter A system capable of simultaneously performing radiative cooling and solar heating Temperature reduction of 14.5°C obtained under laboratory conditions Over 12°C temperature reduction obtained in an outdoor environment Gan and Zhou et al. present a double-sided passive cooling system with significant cooling performance that requires no consumption of electricity. By directing thermal emission from both surfaces of a vertically aligned emitter to the sky, they realize a temperature reduction of over 12°C in an outdoor environment.