Hybrid Passive Cooling: Towards the Next Breakthrough of Radiative Sky Cooling Technology

Abstract

Radiative sky cooling is a promising passive cooling technology without any energy consumption and greenhouse gas production. It has been extensively studied in the past decades. However, its relatively low cooling power (~100 W/m2) presents the significant barrier to the commercial deployment. For broader applications, integrating phase change and evaporative cooling can significantly enhance the cooling performance and temperature control capabilities of radiative sky cooling. In this review, we summarized the recent advance of hybrid cooling by incorporating radiative cooling with phase change cooling or evaporative cooling. The regulation mechanism of hybrid cooling is firstly discussed to reveal the detailed working principle. Subsequently, the structure form and cooling performance of hybrid cooling are summarized to fully clarify the core points of material design and highlight their benefits. In addition, the application scenarios of hybrid cooling are further discussed to underline their promising application potential. Last but not the least, the challenges and prospects are presented to advance the commercial application of hybrid cooling.