This work presents a preliminary experimental performance study of a novel dual-layer emitter for all-day radiation cooling. The emitter comprises a Barium Sulphate (BaSO4) coating on a silver substrate. The cooler was tested in Abuja's tropical climate for diurnal and nocturnal operations. The reflectivity of the emitter is 0.98, which allows it to reflect light from the visible to the near-infrared spectrum with near-black emittance in the mid-infrared. The findings demonstrate that, with an average sub-ambient temperature of roughly 5 °C in direct sunlight, the passive radiative cooling system produced a good cooling effect. About 120 W/m2 measured cooling power density has been determined. This indicates that improving the efficiency of the passive radiative coolers now in use for space conditioning is feasible.
