Theoretical and experimental research towards the actual application of sub-ambient radiative cooling

Abstract

Sub-ambient radiative cooling has drawn abundant research interest, due to its great energy saving potential. However, the challenge of lacking suitable wind cover material seriously impedes its actual application. To address the challenge, the radiative cooling model with wind cover should be developed firstly. In this work, an accurate radiative cooling model considering the solar and mid-infrared transmissivity of wind cover is developed systematically. Subsequently, the radiative cooling experiments with the polyethylene film wind cover of different thickness are designed to validate the accuracy of the developed model. The experimental results demonstrate that wind cover has a significant impact on radiative cooling performance and the developed model has a high accuracy, with an average relative error of below 3%. Additionally, the developed model is used to investigate the radiative cooling performance in different areas. The modeling results indicate that radiative cooling has a great potential in arid areas. More significantly, feasible breakthrough route towards the rigid wind cover is discussed. The results indicate that the minimum target transmissivity of ultra-white glass and zinc selenide wind covers gradually improve with the increase of humidity. Our work provides a platform to address the challenge of lacking suitable wind cover and promotes the actual application of radiative cooling technology.