Feasibility research on a double-covered hybrid photo-thermal and radiative sky cooling module

As an entirely passive cooling strategy, radiative cooling (RC) is an appealing approach to draw heat from the terrestrial surface to outer space. RC can be easily and effectively realized during the nighttime with the absence of sunlight, which coincidently mismatches the operation time of solar collectors. Therefore, it is of possibility and significance to unite the RC device and solar collector to extend the working period and function. In the present work, a novel combined photo-thermal and radiative cooling (PT-RC) module was proposed, experimentally and numerically investigated. By applying separated heating and cooling components, the PT-RC module demonstrated a daytime stagnation temperature of 159.8 °C and a nighttime one of 0.6 °C through a consecutive 24 h experimental duration. By contrast, a conventional photo-thermal (PT) module as a reference showed the highest panel temperature of 153.5 °C during the daytime and the lowest panel temperature of 7.9 °C in the nighttime. Further modeling was conducted to evaluate the thermal performance of the proposed PT-RC module compared with stand-alone PT module and spectrally coupled PT-RC module under different working conditions. This dual-function collector may contribute a potential solution for sustainable energy technology in Zero Energy Building applications.