Numerically enhancing daytime radiative cooling performance of random dielectric microsphere coatings by hollow structures
Numerically enhancing daytime radiative cooling performance of random dielectric microsphere coatings by hollow structures
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DOI：
10.1117/1.jpe.11.042108
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发表时间：
2021-10
影响因子：
1.7
通讯作者：
Meijie Chen;Shuang Li;Dan Pang;Yanwei Zhao;Yuan Yang;Hong-jie Yan
中科院分区：
文献类型：
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作者：
Meijie Chen;Shuang Li;Dan Pang;Yanwei Zhao;Yuan Yang;Hong-jie Yan
抽象。用于被动式日间辐射冷却（PDRC）的介电微球涂层由于其低成本和大规模生产的潜力而受到关注。通过设计适合PDRC应用的微球，可以进一步提高冷却性能，以有效地反射太阳辐射并向寒冷的天空发射热辐射。为了提高介电微球涂层的PDRC性能，对中空介电结构进行了数值设计。当填充率f = 0.6，外半径rout = 0.5 μm，核壳比φ = rin / rout = 0.3，厚度t = 300 μm，热红外发射率ε <$LWIR = 0.90时，可获得最大太阳反射率（R <$solar = 0.96）。此外，通过将多尺寸球体分布控制在φ = 0.1至0.5范围内，在t = 300 μm处的冷却性能提高到R <$solar = 0.98，ε <$LWIR = 0.95，并且在25°C的温度下实现了77 W / m2的净冷却功率。其比单一尺寸球涂层（φ = 0.3）所获得的高1.38%，比固体SiO2球涂层（φ = 0）所获得的高1.64%。这些结果表明，空心结构可以有效地提高冷却性能的介质微球涂层之间的空气和介质材料的界面的数量。
Abstract. Dielectric microsphere coatings for passive daytime radiative cooling (PDRC) are gaining attention owing to their low cost and potential for mass production. The cooling performance could be further enhanced to effectively reflect solar radiation and emit thermal radiation to the cold sky by designing microspheres suitable for PDRC applications. Hollow dielectric structures were numerically designed to enhance the PDRC performance of dielectric microsphere coatings. The maximum solar reflectance (R¯solar = 0.96) was obtained with a fill rate f = 0.6, outer radius rout = 0.5 μm, core–shell rate φ = rin / rout = 0.3, thickness t = 300 μm, and thermal infrared emittance ε¯LWIR = 0.90. Furthermore, by controlling the multisize sphere distribution within φ = 0.1 to 0.5, the cooling performance at t = 300 μm was enhanced to R¯solar = 0.98, ε¯LWIR = 0.95, and a net cooling power of 77 W / m2 was achieved at a temperature of 25°C, which was ∼38 % higher than that achieved with the single-size sphere coating (φ = 0.3) and ∼64 % higher than that of the solid SiO2 sphere coating (φ = 0). These results indicate that hollow structures can effectively enhance the cooling performance of dielectric microsphere coatings by increasing the number of interfaces between the air and dielectric materials.