Author(s)

Zichen Liu, Chunyan Dong, Xinyue Ma, Yan Li

Corresponding Author

Zichen Liu

Abstract

In this paper, a systematic modeling framework based on optical admittance method and particle swarm optimization is proposed for the design and optimization of passive daytime radiative cooling multilayer thin film structures. In the first step, the optical model of PDMS thin film is established, and the emissivity and solar absorption at the atmospheric window of 8–13 μm are calculated by using the temperature-corrected Sellmeier dispersion relationship and hemispheric integral, and the optimal thickness range is 15–25 μm, the atmospheric window emissivity is 0.38–0.39, and the solar absorption rate is about 0.905. In the second step, the energy balance model was constructed, combined with the spectral cooling efficiency function, and the ambient temperature was found to be the main factor affecting the cooling performance through Sobol sensitivity analysis, and the optimal thickness was 6.04 μm, and the net cooling power was 143.67 W/m² and the temperature drop was 0.13 K. In the third step, a mixed integer nonlinear programming model of multi-layer structure is established, and the material selection and layer thickness are optimized by using the adaptive inertial weighted particle swarm algorithm, and the four-layer structure PDMS–TiO₂–SiO₂–TiO₂ is obtained, with an atmospheric window emissivity of 0.8065, a solar absorption rate of 0.1203, and a selectivity ratio of 6.7. The results show that the proposed model can effectively guide the design and optimization of radiation-cooled multilayer structures.

Keywords

Optical admittance method; Particle swarm algorithm; EPareto optimization; Passive daytime radiative cooling