A generalized modelling approach to performance analysis of radiative sky cooling with complicated configurations and external environments

Radiative sky cooling (RC), capable of self-cooling to sub-ambient temperatures by radiatively dissipating heat to the frigid outer space without energy input. Existing modelling approaches characterizing RC performance often assume the RC emitter is exposed to an unobstructed view of the cold sky, neglecting the complex radiative heat interactions between the emitter and its local warm surroundings. This oversight leads to a deviation in RC performance prediction. To address this issue, a straightforward and universal modelling approach is developed to characterize the emitter's radiative heat exchange with both the sky and immediate surroundings, mirroring real-world conditions. Results indicate that, in an obstacle-free environment, the cooling power of the two-dimensional inverted trapezoidal-RC module with a flat emitter is increased by 10.70% compared to the traditional flat-RC module. However, using the trapezoidal-RC module with a 60° inclined V-shaped emitter leads to a decrease in cooling performance to 75.80% of the module with a flat emitter. Additionally, when changing the local surroundings, the approach can still distinguish the cooling performance difference on RC modules under different sky dome coverage ratios. This modelling approach offers a strategy for precisely characterizing RC module's cooling capacities, demonstrating the potential for discerning RC performance differences in complex scenarios.