Comprehensive evaluation of integrating radiative sky cooling with compound parabolic concentrator for cooling flux amplifying

The low cooling density of RC technology makes it challenging to meet the cooling requirements of buildings, particularly during the day with intense solar radiation. To address this challenge, a novel RC module coupled with a compound parabolic concentrator (CPC-RC module) was proposed. In this paper, a universal modelling approach is used to characterize the cooling performance of CPC-RC module, showing 18.1% higher than that of flat module during nighttime. However, the CPC's solar concentrating characteristic impacts the RC emitter's daytime performance. To tackle this issue, exploring the optimal tilt angle of CPC-RC module on typical days to eliminate the influence of solar concentrating property is needed. The results indicate that on 21st June, average cooling power of 121.29 W/m2 is achieved when the module is tilted 25° to the anti-sunward side, 15.7% higher than the module placed horizontally. Additionally, this paper shows that the cooling performance of CPC-RC module with non-ideal emitter is still higher than that of flat one, demonstrating CPC's ability to mitigate the rigorous spectral requirements for emitters. This CPC-RC module offers good cooling effect and shows its great potential for integration into buildings, offering a new research direction for the wider application of RC technology.