The complexity of the spectral emissivity of actual surfaces is the key point in the research and applications of radiation temperature measurement, resulting in the difficulty in the achievement of the temperature measurement. In the present paper, based on the discussions of the Taylor expansion, the non-dimension wavelength and the exponent, the authors describe the mathematical expression of the spectral emissivity of actual surfaces, and establish the general spectral emissivity function. Through the fitting of experimental data of the spectral emissivities of different metals at different temperatures, the applicability of the spectral emissivity function is verified which especially becomes the fundamental in the research of primary spectrum pyrometry.
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January 2025
School of Mechanical Engineering, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul, 02841, Republic of Korea.
Passive temperature controls like passive daytime radiative cooling (PDRC)-heating (PDRH), and thermal insulation are essential to meet the growing demand for energy-efficient thermal solutions. When combined with advanced functions like electromagnetic interference shielding, these technologies can significantly enhance scalability. However, existing approaches using single thin films or uniform porous materials face inherent limitations in optimizing versatile functions, while lightweight, insulating aerogels can extend their multifunctionality by manipulating pores and fillers.
View Article and Find Full Text PDFLangmuir
January 2025
Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8, Czech Republic.
Black aluminum is a material characterized by high surface porosity due to columnar growth and exhibits unique optical properties that make it attractive for applications such as light trapping, infrared detection, and passive thermal radiation cooling. In this study, we correlate the structural and optical properties of black aluminum by comparing it with conventional reflective aluminum layers. These layers of varying thicknesses were deposited on fused silica substrates, and their optical properties were analyzed.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
School of Energy and Environment, City University of Hong Kong, Kowloon 999077, Hong Kong.
Nanomicro Lett
December 2024
Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies, College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China.
Dual-band electrochromic devices capable of the spectral-selective modulation of visible (VIS) light and near-infrared (NIR) can notably reduce the energy consumption of buildings and improve the occupants' visual and thermal comfort. However, the low optical modulation and poor durability of these devices severely limit its practical applications. Herein, we demonstrate an efficient and flexible bifunctional dual-band electrochromic device which not only shows excellent spectral-selective electrochromic performance with a high optical modulation and a long cycle life, but also displays a high capacitance and a high energy recycling efficiency of 51.
View Article and Find Full Text PDFScience
December 2024
Center for Complex Particle Systems (COMPASS), University of Michigan, Ann Arbor, MI, USA.
Planck's law ignores but does not prohibit black-body radiation (BBR) from being circularly polarized. BBR from nanostructured filaments with twisted geometry from nanocarbon or metal has strong ellipticity from 500 to 3000 nanometers. The submicrometer-scale chirality of these filaments satisfies the dimensionality requirements imposed by fluctuation-dissipation theorem and requires symmetry breaking in absorptivity and emissivity according to Kirchhoff's law.
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