Regulating thermal radiation for energy and sustainability
Regulating thermal radiation for energy and sustainability
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DOI：
10.1016/j.nxener.2023.100019
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
Q. Cheng;G. Ho;A. Raman;Ronggui Yang;Yuan Yang
中科院分区：
文献类型：
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作者：
Q. Cheng;G. Ho;A. Raman;Ronggui Yang;Yuan Yang
热辐射是由物质中的粒子（如电子、原子和分子）的热运动产生的电磁辐射。这是物质在绝对零度以上的有限温度下的普遍现象。热辐射在从纳米尺度到天体尺度的各种能量过程中起着重要作用，从太阳辐射到地球的能量预算，从微波炉到个人热管理。因此，对热辐射的有效调控可以对能源和可持续性产生广泛的影响，例如地球工程、海水淡化以及能源生产和收获[1]。（图1a），每单位面积辐射的总功率又由斯蒂芬-玻尔兹曼定律描述为总辐射功率P= π σT4。这里T是黑体的表面温度，σ是Stefan-Boltzmann常数，等于5.67× 10-8 W m-2 K-4。辐射率是平均光谱和方向发射率，值在0和1之间，等于辐射功率与黑体功率的比值。普朗克定律起源于光子能量分布的统计力学观点，强调了热发射体的光谱辐射在本质上是宽带的。例如，太阳是一个典型的黑体，表面温度约为6000 K，因此其大部分强度在0.3-2.5 μm的波长范围内辐射，从紫外线到近红外线。工业高温过程和聚光太阳能热转换通常存在于500-3000 K的温度范围内，相应的感兴趣光谱为1-10 µm。在环境温度（例如，250-500 K）附近，感兴趣的光谱为5-50 µm。因此，调节热辐射需要精确控制宽带光谱。这是一个独特的区别于其他主题的光子学，侧重于窄带或单色控制。
Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter, such as electrons, atoms and molecules. It is a universal phenomenon for matter at a finite temperature above absolute zero Kelvin. Thermal radiation plays an important role in a wide range of energy processes from nanoscale to celestial dimensions, ranging from the solar radiation to Earth’s energy budget, and from microwave ovens to personal thermal management. Therefore, effective regulation of thermal radiation can have a remarkable broad range of impacts on energy and sustainability, such as geoengineering, desalination, and energy generation and harvesting [1].The spectral density of radiation emitted by a black body is described by Planck’s law (Fig. 1a), with the total power radiated per unit area in turn described by the Stefan-Boltzmann law as the total radiation power P= ̅σT4. Here T is the black body’s surface temperature, σ is the Stefan–Boltzmann constant, which equals to 5.67× 10-8 W m-2 K-4. ̅ is the average spectral and directional emissivity, a value between 0 and 1, which is equal to the ratio of power radiated to that of a blackbody. Planck’s law, originating as it does from a statistical mechanical view of photon energy distributions, highlights that the spectral radiance of a thermal emitter is broadband in nature. For example, the Sun is a prototypical blackbody with a surface temperature of~ 6000 K, thus radiating most of its intensity in the wavelength range of 0.3-2.5 µm, from the ultraviolet to near infrared. Industrial high temperature processes and concentrated solar thermal conversion typically exist in the temperature range of 500-3000 K, and the corresponding spectrum of interest is 1-10 µm. Around ambient temperature (eg, 250-500 K), the spectrum of interest is 5-50 µm. Therefore, regulating thermal radiation requires accurate control of a broadband optical spectrum. This is a unique difference from other topics in photonics which focus on narrowband or monochromic control.