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Spectral absorption control of femtosecond laser-treated metals and application in solar-thermal devices
摘要： Direct femtosecond (fs) laser processing is a maskless fabrication technique that can effectively modify the optical, electrical, mechanical, and tribological properties of materials for a wide range of potential applications. However, the eventual implementation of fs-laser-treated surfaces in actual devices remains challenging because it is difficult to precisely control the surface properties. Previous studies of the morphological control of fs-laser-processed surfaces mostly focused on enhancing the uniformity of periodic microstructures. Here, guided by the plasmon hybridisation model, we control the morphology of surface nanostructures to obtain more control over spectral light absorption. We experimentally demonstrate spectral control of a variety of metals [copper (Cu), aluminium (Al), steel and tungsten (W)], resulting in the creation of broadband light absorbers and selective solar absorbers (SSAs). For the first time, we demonstrate that fs-laser-produced surfaces can be used as high-temperature SSAs. We show that a tungsten selective solar absorber (W-SSA) exhibits excellent performance as a high-temperature solar receiver. When integrated into a solar thermoelectric generation (TEG) device, W-SSA provides a 130% increase in solar TEG efficiency compared to untreated W, which is commonly used as an intrinsic selective light absorber.
关键词： spectral light absorption,plasmon hybridisation model,selective solar absorbers,solar thermoelectric generation,broadband light absorbers,femtosecond laser processing
更新于2025-09-19 17:13:59
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Diffractive gratings to improve TiAlN based spectrally selective solar absorbers
摘要： Based on an optimized TiAlN multilayer structure achieving high absorption and low thermal emission at temperatures above 500°C for CSP receivers, the authors demonstrate that - sub-wavelength period gratings associated with the multilayer can further increase the absorption and thus the efficiency of the CSP system. The C-method (Chandezon Method) is used to theoretically optimize the grating profiles. An experimental demonstration of the combination of lithographic grating fabrication and absorptive layer deposition using Inconel 625 as substrates is also presented. Experimental results show that the microtexturing increases the absorption from 91% to 95% while the emissivity at 550°C is kept at an acceptable level, increasing from 32% to 38%, representing an enhancement of almost 3% of the photothermal efficiency in comparison to non-structured coatings. Textured absorbers were annealed in air at 500°C and demonstrated high thermal stability of their optical properties during more than 336h. Textured absorber would also be greatly efficient for CSP plants working at lower temperature (250-300°C), such as linear Fresnel CSP for process heat production, since optical properties and thermal stability will be excellent at these temperatures.
关键词： diffractive gratings,TiAlN,photothermal efficiency,CSP receivers,spectrally selective solar absorbers
更新于2025-09-04 15:30:14