Extending the operation of a solar air collector to night-time by integrating radiative sky cooling: A comparative experimental study

Solar thermal collectors are generally unproductivity at night without sunlight. Radiative cooling, on the other hand, is another renewable technology harvesting coldness from extraterrestrial space and can effectively work nocturnally. Therefore, this study proposes a scheme that integrates nocturnal radiative cooling mechanism into solar air collector as supplementary. Incoming heated by absorber during daytime cooled down glass cover night. Experimental results indicate that, with an mass flow rate of 0.03 kg/s, dual-mode (named PT-RC collector) realized efficiency 34.2% zero-reduced temperature (e.g., when inlet equals ambient temperature) net power 27.9 W/m2, which 72.2% 2.4 times those typical collector. As increased 0.01 to 0.05 two performance indicators lifted 19.8% 34.5% 16.9 33.0 respectively. The shows potential be applied in four-season regions where heating both required throughout year or tropical zones much more desired.