辐射制冷膜的性能分析与优化设计

PERFORMANCE ANALYSIS AND OPTIMIZATION DESIGN OF RADIATION COOLING FILM

根据基尔霍夫定律和光学薄膜理论,利用光学设计软件Macleod研究辐射制冷膜的材料与结构对制冷性能的影响。辐射制冷膜要求在0.3~3.0μm的太阳波段具有较高反射率,阻止物体得热;在8~13μm的红外波段具有较高发射率,降低自身温度。研究发现:由于SiO_(2)在8~13μm波段的反射率低,在其他波段的反射率高,是制造辐射膜的理想材料。高分子聚合物PS与SiO_(2)交替叠加形成的复合膜在8~13μm波段会产生声子-极化子激发的共振现象,可进一步降低反射率,因此PS是提高辐射制冷薄膜性能的有效辅助材料。经过Simplex法优化,得到辐射制冷膜以SiO_(2)-PS-SiO_(2)结构组合,各层厚度依次为0.2、0.8、70μm时,其辐射力高达136.2 W/m^(2),平均发射率达到92.12%。

Based on Kirchhoff’s law and optical thin film theory,the Macleod software is used to investigate the effect of the material and structure of radiant cooling films on the cooling performance. The radiant cooling film requires high reflectivity in the solar band of 0.3-3.0 μm to prevent the object from heat gain. It also requires a high emissivity in the infrared band of 8-13 μm,which lowers its own temperature. It is found that SiO_(2) has a low reflectance in the 8-13 μm band and a high reflectance in other bands,making it be an ideal material for the fabrication of radiation cooling films. The composite film formed by the superposition of high molecular polymer PS and SiO_(2) will produce the resonance phenomenon of phonon-polaron excitation in the 8-13 μm band,which can further reduce the reflectivity. Therefore,PS is an effective auxiliary material for improving the performance of radiation cooling films. After optimization by Simplex method,the radiant cooling film is combined with SiO_(2)-PS-SiO_(2) structure. When the thickness of each layer is 0.2 μm,0.8μm and 70 μm,repectively,the radiation force is as high as 136.2 W/m^(2),and the average emissivity reaches 92.12%.