Preparation and cooling performance analysis of double-layer radiative cooling hybrid coatings with TiO_(2)/SiO_(2)/Si_(3)N_(4) micron particles  

作　　者：赵洋春 周勇敏 Yang-Chun Zhao;Yong-Min Zhou(College of Materials Science and Engineering,Nanjing Tech University,Nanjing 211816,China)

机构地区：[1]College of Materials Science and Engineering,Nanjing Tech University,Nanjing 211816,China

出　　处：《Chinese Physics B》2023年第11期498-507,共10页中国物理B（英文版）

摘　　要：Passive daytime radiative cooling is achieved by radiating heat into outer space through electromagnetic waves without energy consumption. A scalable double-layer coating with a mixture of TiO_(2), SiO_(2), and Si_(3)N_(4)micron particles for radiative cooling is proposed in this study. The finite-difference time-domain algorithm is used to analyze the influence of particle size and coating thickness on radiative cooling performance. The results of the simulation show that the particle size of 3 μm can give the best cooling performance, and the coating thickness should be above 25 μm for SiO_(2)coating. Meanwhile, the mixture of SiO_(2)and Si_(3)N_(4)significantly improves the overall emissivity. Through sample preparation and characterization,the mixture coating with a 1:1 ratio addition on an Al substrate exhibits high reflectivity with a value of 87.6% in the solar spectrum, and an average emissivity of 92% in the infrared region(2.5 μm–15 μm), which can be attributed to the synergy among the optical properties of the material. Both coatings can theoretically be cooled by about 8℃ during the day and about 21℃ at nighttime with hc = 4 W·m^(-2)·K^(-1). Furthermore, even considering the significant conduction and convection exchanges, the cooling effect persists. Outdoor experimental results show that the temperature of the double-layer radiative cooling coating is always lower than the ambient temperature under direct sunlight during the day, and can be cooled by about 5℃ on average, while lower than the temperature of the aluminum film by almost 12℃.

关 键 词：radiative cooling coatings thermal radiation infrared emissivity 

分 类 号：TB306[一般工业技术—材料科学与工程]