AI 中文总结
受向日葵向光性启发，提出动态天空视角因子转向系统，通过动态调整发射器角度，实现全天候亚环境冷却，放宽材料要求并提升冷却功率，最高年节电200 kWh/m^2。
AI 中文摘要
被动日间辐射冷却在解决能源-水关联等可持续性挑战方面具有巨大潜力。然而，常见的静态水平配置无法响应太阳位置和云量等环境条件的动态变化，从而丧失了在24小时昼夜循环中优化冷却性能的机会。在此，受向日葵向光性的启发，我们开发了一种动态天空视角因子转向（DSVFS）系统。通过将发射器动态转向至最佳角度，该系统不仅放宽了辐射发射器对超高太阳反射率和红外发射率的严格双重需求，而且全天候最大化其冷却功率。利用该DSVFS系统，我们实验证明了即使在典型炎热正午，使用近黑体发射器也能实现亚环境温度冷却；使用选择性发射器时，与静态对应物相比，冷却功率增加了135%。对全球多个城市的案例研究表明，最大年节电量可达200 kWh/m^2。
英文摘要
Passive daytime radiative cooling holds significant potential to address sustainability challenges such as the energy-water nexus. However, common static horizontal configurations cannot respond to dynamic changes of environmental conditions such as solar position and cloud coverage, thereby forfeiting the opportunity of optimizing the cooling performance in the 24-h day-night cycle. Here, inspired from the heliotropism of sunflowers, we develop a dynamic sky view factor steering (DSVFS) system. By dynamically steering the emitter to an optimal angle, this system not only relaxes the stringent dual requirement of ultra-high solar reflectivity and infrared emissivity of the radiative emitter, but also maximizes its cooling power round-the clock. Using this DSVFS system, we experimentally demonstrate sub-ambient cooling during a typical hot noon even with a near-blackbody emitter; with a selective emitter, we demonstrate an increase of cooling power by 135% as compared to its static counterpart. Case studies of multiple cities across the world indicate a maximum annual electricity saving of up to 200 kWh/m^2.
Comments16 pages and 5 figures of the main text; 17 pages and 10 figures and 8 sections of Supporting Information
