Hybrid concentrated radiative cooling and solar heating in a single system
Lyu Zhou, Haomin Song, Nan Zhang, Jacob Rada, Matthew Singer, Huafan Zhang, Boon S. Ooi, Zongfu Yu, Qiaoqiang Gan
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/m2. 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/m2 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.