Modeling and simulation of seasonal performance of silica-polymethylpentene for diurnal radiative cooling under direct sunlight

Passive radiative cooling presents a smart alternative energy solution to the increasing demand for energy, especially for thermal comfort, as it requires energy input while being environmentally friendly. Achieving cooling through radiation is, however, material dependent. This study investigates the seasonal performance of a radiative cooling arrangement for all-year cooling. A 2D mathematical model of a diurnal radiative cooler was developed from first principles based on thermal energy balance and was parameterized using the climatic data of Owerri, Nigeria, to evaluate the thermal performance of the cooler during the late Harmattan (January), early rainy (April), late rainy (September), and early Harmattan (November) seasons in the study location. The months so chosen and their peculiar climatic characteristics are representative of the four seasons that characterize the study location. The system showed appreciable cooling under direct sunlight in all the months, indicating that diurnal passive radiative cooling is feasible all year round. Sub-ambient temperature values of 5, 3, 3.4, and 5 °C were recorded for the months of January, April, September, and November, under solar irradiance of 1250, 1150, 950, and 1200 W/m2 and cooling powers of 94, 107, 84, and 96 W/m2, respectively.