一种基于辐射制冷和太阳能制热的温度自适应双层薄膜

A smart thermal-gated bilayer membrane for temperature-adaptive radiative cooling and solar heating

传统的制冷、制热技术能源消耗量巨大,而利用太空和太阳作为天然冷源和热源的辐射制冷和太阳能制热技术由于零能耗、低碳排的特点受到了研究者们的广泛关注,然而,目前被动式制冷/制热器件通常只能实现单一功能、无法满足动态环境条件下多变的制冷/制热需求,本文提出了一种温度自适应的智能控温双层薄膜(STG),以辐射制冷技术和太阳能制热技术为基础,可以随温度响应实现不同环境条件下制冷/制热模式的智能切换,当温度低于其境界温度时,STG膜在太阳光波段从高反射切换为高吸收(反射率由0.962变为0.059),而中红外发射率始终保持在0.95.该光谱特性使得STG膜在夏季直射阳光(辐射峰值>900Wm)下能够实现比环境温度低5°C的亚环境日间辐射冷却,而在冬季则能实现550Wm²的太阳光加热功率。作者同时通过理论模拟验证当STG膜被大规模应用时,这种可智能切换的制冷/制热装置在节能方面展现出了巨大的应用潜力该设计策略能够为零能耗的热响应控温器件提供新的思路,并为实现能源的可持续发展提供新的途径。

Due to the huge energy consumption of traditional cooling-and heating-based electricity,passive radiative cooling and solar heating with a minimum carbon footprint using the outer space and Sun as natural thermodynamic resources have attracted much attention.However,most passive devices are static and monofunctional,and cannot meet the practical requirements of dynamic cooling and heating under various conditions.Here,we demonstrate a smart thermal-gated(STG)bilayer membrane that enables fully automatic and temperature-adaptive radiative cooling and solar heating.Specifically,this device can switch from reflective to absorptive(white to black)in the solar wavelength with the reduction in optical scattering upon ambient temperature,corresponding to a sunlight reflectivity change from 0.962 to 0.059 when the temperature drops below30℃,whereas its mid-infrared emissivity remains at0.95.Consequently,this STG membrane achieves a temperature of5℃below ambient(a key signature of radiative cooling)under direct sunlight(peak solar irradiance>900 W m^(-2))in summer and a solar heating power of550Wm^(-2)in winter.Theoretical analysis reveals the substantial advantage of this switchable cooling/heating device in potential energy saving compared with cooling-only and heating-only strategies when widely used in different climates.It is expected that this work will pave a new pathway for designing temperature-adaptive devices with zero energy consumption and provide an innovative way to achieve sustainable energy.