| Solar energy,as a clean and environmentally friendly,huge amount of renewable energy,has gained extensive attention.In modern society where fossil energy is depleted and environmental pollution is serious,the development of solar energy utilization technology is becoming an effective way to overcome them.Solar thermal properties of plasmonic nanostructures are widely used in solar collectors,solar cells and solar thermal catalysis.The premise of these applications requires effective regulation of the nanostructured photo-thermal conversion characteristics to achieve excellent performance.Therefore,in this study,the photo-thermal conversion properties of nanostructure were inveatigated to tune the spectra of nanoparticles and absorbers for solar thermal conversion applications.For nanoparticles,the photo-thermal properties of nanoparticle and suspension were studied,and the solar thermal conversion experiment was carried out.For absorbers,selective absorption properties of the absorber were studied for solar thermal converisn applications,and then the solar thermal covnerision properties of smart coatings were studied.For the regulation of nanoparticle optical properties,finite-difference time-domain method was used.The effect of the particle size,morphology and dielectric environment of nanoparticles on the optical properties was studied.At the same time,the peak wavelength can be tuned by changing the core-shell ratio and materials.Solar absorption performance can be enhanced in the nanoparticle suspension by simply mixing the particles and changing the composition of particles.For the regulation of nanoparticle photo-thermal response process,finite element method was used.The effect of the incident light,particle shape,material on the temperature field was studied to obtain regulation mechanism of local heating.The wavelength and angle of the incident light can be modulated to selectively heat one of the particles in the dimeric particle system.Finally,optimization results of the absorption cross-sectional area,absorption coefficient,photo-thermal conversion efficiency and local temperature rise for core-shell nanoparticles were compared to reveal the correlation between different optimization parameters.For solar thermal conversion properties of nanparticles and their suspensions,experiments were conducted to study.Au nanoparticles with different sizes and morphologies were prepared.Small-sized particles were more suitable for solar thermal utilization,and Au thorns had better light-to-heat conversion efficiency than Au spheres.For the two-component nanoparticles,solar thermal conversion efficiency of Au-Ag blended nanoparticles was approximately equal to the sum of the one-component nanoparticles,and the solar-thermal conversion performance of the Au-Ag alloy nanoparticles was better than the physically mixture under the same conditions.For the grating structure selective absorption coating,finite element method was used to calculate the spectra,and the effect of different structures and materials on the spectra of the coating was investigated.In terms of structural design,based on the classical metal-dielectric--metal structure,different width grating structures were arranged in the vertical direction to obtain selective absorption of the target wavelength.In terms of material selection,the intrinsic absorption properties of metals had a significant effect on the broadband absorption properties of simple nanostructures.The selection of high imaginary dielectric constant metals contributes to the formation of a broad absorption spectrum.For the porous structure selective absorbing coating,dealloying method was used to obtain Ni porous structure selective asborbers with the high dielectric constant imaginary part.Experimental results showed that the average solar energy absorption efficiency / infrared emittance can reach 0.93/0.12 or 0.88/0.08.Metal Ni has the high thermal and chemical stability,and the accumulation of thermal stress between single components is little.Stability and durability experiments showed that the porous absorber had good stability and excellent durability to be a promising solar thermal conversion coating.For the solar thermal response smart coating and windown appliations,the VO2 phase change material was introduced into the one-dimensional grating structure to design an intelligent temperature control coating.Under high temperature conditions,the coating had a higher infrared emittance;at low temperatures,it had a lower infrared emittance.In deep space environments,the temperature of the coating can be controlled to be near its phase transition temperature.Finally,plasmonic nanoparticles were added to the temperature-sensitive hydrogel system to obtain solar thermal response smart windows with different particle concentrations and critical temperatures. |
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