Jeon Suwan, Shin Jonghwa
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
Sci Rep. 2020 Aug 3;10(1):13038. doi: 10.1038/s41598-020-70105-y.
We investigate the fundamental limit of radiative cooling of objects on the Earth's surfaces under general conditions including nonradiative heat transfer. We deduce the lowest steady-state temperature attainable and highest net radiative cooling power density available as a function of temperature. We present the exact spectral emissivity that can reach such limiting values, and show that the previously used 8-13 μm atmospheric window is highly inappropriate in low-temperature cases. The critical need for materials with simultaneously optimized optical and thermal properties is also identified. These results provide a reference against which radiative coolers can be benchmarked.
我们研究了包括非辐射热传递在内的一般条件下地球表面物体辐射冷却的基本极限。我们推导了作为温度函数的可达到的最低稳态温度和可用的最高净辐射冷却功率密度。我们给出了能够达到这些极限值的精确光谱发射率，并表明先前使用的8 - 13微米大气窗口在低温情况下非常不合适。我们还确定了对具有同时优化的光学和热学性质的材料的迫切需求。这些结果提供了一个可用于衡量辐射冷却器性能的参考标准。
