Research On Thermal-optical Properties And Processing Parameters Of Microstructure Array Optical Glas

The rapid growth of the global population is increasing the energy consumption of cooling,heating and lighting systems,resulting in hundreds of thousands of tons of additional CO₂emissions each year.In order to achieve"2030 carbon peak and 2060 carbon neutral",it is important to develop effective energy saving technologies.The rational use of solar radiation energy will provide a better strategy for the realization of zero energy efficient outdoor thermal management.Currently reported infrared-reflective polymer films/coatings sacrifice visible light transmission while reflecting infrared during daytime,and the radiative cooling is limited;while a single film material only has the function of cooling or heating,which cannot meet the demand of cooling/heating year-round thermal management applications.In this paper,a microstructured optical glass with high visible light transmission and high near-infrared light reflection is prepared by coupling the reflective microstructure and thermal insulation coating to the optical glass,which not only transmits more than 95%of visible light but also reduces the transmission rate of thermal radiation concentrated in 1.2-2.5μm near-infrared light wavelength under the solar environment,thus achieving passive cooling.Secondly,the coupling of the reflectance-reducing microstructure and the thermal insulation coating can reduce the infrared wavelength transmission in the 2.5-13μm wavelength band in the room under the low-temperature external environment to achieve indoor warming.The main research contents and conclusions include:（1）Exploring the macro-micro-optical properties of the reduced-reflection microstructure coupled with thermal insulation coating on optical glass.Based on Snell’s law and Maxwell’s equations in the time domain finite difference method,the influence of different microstructure top angle,duty cycle,structure period and coating thickness on the visible-near-infrared light transmission rate of microstructured optical glass was investigated.The results show that the optimal parameters of the microstructured optical glass are the duty cycle z=1,the top angleα=60°,the coating thickness h=400 nm and the structure period p=70μm,and the average visible and near-infrared light transmission rates are 77.7%and 18.9%,which are 17.1%and2.3%higher than those of a single coating.（2）Femtosecond laser processing of optical glass anti-reflective microstructures and its evaluation.Femtosecond laser processing technology was used to process microstructure arrays on the surface of optical glass,and the effects of femtosecond laser processing processes（such as single pulse energy,scanning speed and number of scans）on the face shape accuracy of microstructure arrays were investigated.The results show that the microstructure period is about 67μm,the depth is about 54μm,the microstructure top angleα≈62°and the duty cycle z≈1.Compared with the ideal structure of the theoretical model,the microstructure depth and the structure period of the microstructured optical glass are 4.3%.The relative errors are 4.3%and 3.3%,respectively.（3）Thermal insulation coating preparation and optical performance analysis of coupled microstructure arrays.The thermal insulation coatings with high visible light transmission and high near-infrared light reflection were prepared,and the effects of dispersant,ball milling time,powder solid content and spin coating speed on their stability and optical properties were investigated.The results showed that the actual average visible and near-infrared light transmission rates of the microstructured optically coated glass were 83.6%and 34.9%,respectively,when the dispersant was PVP,ball milling for 4 hours,6%nanopowder solid content,and spin coating speed of 1500 r/min.（4）Construction of thermal management performance test platform and performance testing in hot/cold environment.The heat insulation and thermal insulation performance of microstructured optical glass in hot/cold environment was measured and its thermal management performance in hot/cold environment was investigated.The results show that the maximum and average temperatures are 23.9℃and 14.8℃lower than those of ordinary glass under infrared light（0.7-3μm）radiation,and 2.9℃and 2℃lower than those of ordinary glass under sunlight radiation.In the cold outdoor environment,the indoor temperature of microstructured optical glass was 1.9℃higher than that of ordinary glass.