Enhanced solar thermal conversion performance of plasmonic gold dimer nanofluids

Absorption characteristics and solar thermal conversion of Fe3O4@Au core/shell nanoparticles for a direct-absorption solar collector

Plasmonic nanofluids show great interests for light-matter applications due to the tunable optical properties. By tuning the nanoparticle (NP) parameters (material, shape, and size) or base fluid, plasmonic nanofluids can either absorb or transmit the specific solar spectrum and thus making nanofluids ideal candidates for various solar applications, such as: full spectrum absorption in direct solar absorption collectors, selective absorption or transmittance in solar photovoltaic/thermal (PV/T) systems, and local heating in the solar evaporation or nanobubble generation. In this chapter, we first summarized the preparation methods of plasmonic nanofluids, including the NP preparation based on the top-down and bottom-up, and the nanofluid preparation based on one-step and two-step. And then solar absorption performance of plasmonic nanofluids based on the theoretical and experimental design were discussed to broaden the absorption spectrum of plasmonic nanofluids. At last, solar thermal applications and challenges, including the applications of direct solar absorption collectors, solar PT/V systems, solar distillation, were introduced to promote the development of plasmon nanofluids.

Achieving high solar energy absorption based on nanofluids (NFs) needs further study in solar photothermal conversion technology. In this work, we performed COMSOL simulations to investigate the solar energy absorption using a core-shell nanostructure composed of the Au core and shell with different materials. The influence of the radius of the Au core, the materials of the shell, and the shell thickness on the solar absorption efficiency factor (SAEF) are systematically studied. The results show that the SAEF of the Au@Li nanoparticle with ratio of 0.5 has the highest SAEF of 1.4779, increasing 1.99 times compared to that of the bare Au nanoparticle of 0.74326 with the same radius. Moreover, the optical properties, electric field distribution, and SAEF of the Au@Li dimer are further evaluated to demonstrate the aggregation effects on SAEF. We find that the SAEF of the Au@Li dimer reaches the maximum of 4.34 with a distance around 1nm, where the LSPR coupling effect in the nanogap is sharply enhanced 700 times irradiated by light with wavelength of 760nm. Finally, the direct absorber solar collector performance demonstrates that Au@Li dimer NFs can collect 93% of solar energy compared to 54% for Au@Li NFs and 51% for Au NFs. This work provides the possibility to achieve more efficient solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

In order to enhance the efficiency of direct absorption solar collectors, this study carried out an experimental analysis about the optical and photothermal conversion performance of Fe3O4, ATO (Antimony-doped tin oxide), and Fe3O4/ATO nanofluids with a total concentration of 0.1 wt%. According to the results of the experiments, Fe3O4 nanofluid outperforms ATO nanofluid in terms of optical absorption; nevertheless, at wavelengths shorter than 600 nm, it also shows significant scattering reflection. The solar-weighted absorption coefficient of Fe3O4/ATO nanofluid rose from 0.863 (mFe3O4/mTotal = 0.2) to 0.932 (mFe3O4/mTotal = 0.8) when the optical path length increased from 0.01 m to 0.06 m. Moreover, the Fe3O4/ATO hybrid nanofluid achieved a photothermal conversion efficiency of 0.932 when the mass ratio of Fe3O4 to total mass was 0.2, surpassing the efficiencies of 0.892 and 0.898 recorded for 0.1 wt% ATO and Fe3O4 nanofluids, respectively. When present together, the opposing optical characteristics of Fe3O4 and ATO boost photothermal conversion performance, which is anticipated to raise the efficiency of direct absorption solar collectors.

Solar-thermal evaporation is an ancient system that generates thermal-induced vapor utilizing solar energy, which is renewable, clean, and has negligible environmental footprints. Though old, this system has recently revived tremendous attraction to the science community because of synthesized high-absorptive materials, smart heat and vapor management, and engineering marvels in device configurations. Integrated as a whole, the solar-thermal evaporation system facilitates improved solar to vapor conversion efficiency at low capital costs. In this review, a comprehensive discussion of physics, chemistry, and engineering behind solar-thermal evaporation systems has been presented in a summary manner. Moreover, this paper potentially addresses freshwater production techniques from sea or wastewater and nexuses some innovative approaches to generate electrical power. This review also presents emerging research activities in various aspects of solar-thermal evaporation with some interesting findings and points out critical advancement deficiencies. The futuristic view of microgrid system integration is also discussed extensively to nexus electrical power generation cleanly. This paper intends to present a comprehensive assessment of current advances in STE systems to encourage primary and practical research in leveraging underutilized supplemental energy sources for future integration of water, energy, and environmental systems with promised research direction and advancement.

Abstract With the explosive growth of the world population and the rapid development of human society and economy, the demand for fresh water is remarkably increasing. The lack of freshwater resources on earth may threaten the survival of hundreds of millions of people worldwide.

The optical characteristics of C@Cu core-shell nanorods for solar thermal applications

Comparative study of thermoplasmonic properties in core-shell nanoparticles for heat generation applications

Nanofluids with full-spectrum absorption properties are highly desirable for direct solar thermal energy conversion applications. In this work, Ag and CsWO3 nanofluids, which exhibit absorption both in the visible and near-infrared (NIR) region, are integrated to obtain two-component hybrid nanofluids. The hybrid nanofluids show broad band absorption with a solar weighted absorption fraction of 99.6%, compared to 18% and 54% for the base liquid (ethylene glycol) and CsWO3 nanofluids, respectively. The highest photo-thermal conversion performance for the hybrid nanofluids is obtained with Ag/CsWO3 weight ratio of 3/7. The solar thermal conversion efficiency of the optimum hybrid nanofluids is 67%, 10% and 15% higher than single Ag and CsWO3 nanofluids. The two-component hybrid nanofluid provides an alternative for making the best use of solar energy.

Developing an expandable ferric tannate/gallate polyurethane sponge evaporator for efficient solar desalination