An all-day cooling system that combines solar absorption chiller and radiative cooling

Although the solar-powered absorption chiller is recently a trending technology for space cooling of buildings, it requires a bulky thermal storage device and complex installations to achieve all-day cooling. In this paper, a new system that couples the solar-driven absorption chiller and radiative sky cooling is proposed to realize 24-h continuous cooling with less floor space and smaller thermal storage. This system involves a specialized module that utilizes the medium temperature flat panel solar collector on its top layer and a selective radiative cooling absorption layer on the bottom layer; The top layer faces the sky during the daytime to collect solar thermal energy to drive the absorption chiller, and it will be flipped to the bottom layer at nighttime to realize radiative cooling. The proposed system is analyzed by coupling the steady-state models of each subsystem and a cooling load model, which are later applied to evaluate the cooling performance under varying weather conditions within a day. The simulation results show that the system can stably meet the cooling demand of 70 m2 room while only needing half the floor area and a thermal storage tank that is 4 times smaller than the traditional PT-AC system.