Comprehensive investigation of daytime radiative cooling technology for sustainable grain storage: A combined approach of field measurement and CFD simulations

Ensuring the thermal-safety of grain storage while achieving an ecologically friendly, energy-efficient solution that contributes to carbon reduction strategy is the future direction for grain storage systems. The application of Radiative Cooling (RC) technology in long-term grain storage is a promising solution in this regard. This study investigates the energy storage and heat transfer properties of the Daytime Radiative Cooling (DRC) metafilm, a type of RC material, in grain storage settings from spring to summer by performing a field measurement on a grain storage of ∼500 m² rooftop and corresponding Computational Fluid Dynamics (CFD) simulations. The results highlight that the DRC metafilm applied to the outer roof surface achieves a peak cooling rate of 38.3 % under direct sunlight, which is a 50.6 % improvement over the non-filmed condition, providing effective heat dissipation and ensuring a continuous passive cooling process in hot environments. Especially in high-temperature summer conditions, the DRC metafilm ensures that both the average grain temperature throughout the storage and the central grain pile temperature meet the standards for quasi-low-temperature grain storage with zero energy consumption. Additionally, during the peak solar radiation intensity of summer, the DRC film acts as an efficient heat dissipator, facilitating negligible surface heat flux on the exterior roof, with localized regions exhibiting positive cooling effects. Consequently, using DRC material engenders tangible economic and substantial environmental benefits for grain storage cooling.