Enhanced efficiency in Concentrated Parabolic Solar Collector(CPSC) with a porous absorber tube filled with metal nanoparticle suspension

In this study, effects of different nanoparticles and porosity of absorber tube on the performance of a Concentrating Parabolic Solar Collector(CPSC) were investigated. A section of porous-filled absorber tube was modeled as a semi-circular cavity under the solar radiation which is filled by nanofluids and the governing equations were solved by FlexPDE numerical software. The effect of four physical parameters, nanoparticles type, nanoparticles volume fraction(φ), Darcy number(Da) and Rayleigh number(Ra), on the Nusselt number(Nu) was discussed. It turns out that Cu nanoparticle is the most suitable one for such solar collectors, compared to the commonly used Fe_3O_4, Al_2O_3, TiO_2.With the increased addition of Cu nanoparticles all the parameters φ, Da and Ra shows a significant increase against the Nu, indicates the enhanced heat transfer in such cases. As a result, low concentration of Cu nanoparticle suspension combined with porous matrix was supposed to be beneficial for the performance enhancement of concentrating parabolic solar collector.

Calculation and Analysis of Acoustic Characteristics of Straight-Through Perforated Pipe Muffler Based on Multilayer Sound Absorbing Material

Using the multi-physical field simulation software COMSOL,the acoustic characteristics of the multilayer sound absorbing material straight-through perforated pipe muffler are studied by the finite element method.The results show that the finite element calculation of the multilayer sound absorbing material straight-through the perforated pipe muffler agrees well with the experimental measurement results.The reliability of the finite element method for studying the acoustic performance of the straight-through perforated pipe muffler with multilayer sound absorbing materials is shown.Furthermore,the influence of some structural parameters of porous sound absorbing material and micro-perforated plate on the acoustic performance of the multilayer sound absorbing material straight-through perforated pipe muffler is analyzed.The muffler based on multilayer sound absorbing material is different from the traditional muffler.After applying the multilayer sound absorbing material to the straight-through perforated pipe muffler,the transmission loss value greatly increases,which provides new ideas and directions for future research on the muffler.

Achieving excellent bandwidth absorption by a mirror growth process of magnetic porous polyhedron structures

A symmetrical Fe2O3/BaCO3 hexagonal cone structure having a height of 10 um and an edge length of -4um is reported, obtained using a common solvothermal process and a mirror growth process. Focused ion beam and high-resolution transmission electron microscopy techniques revealed that α-Fe2O3 was the single crystal feature present. Ba ions contributed to the formation of symmetrical structures exhibited in the final composites. Subsequently, porous magnetic symmetric hexagonal cone structures were used to study the observed intense electromagnetic wave interference. Electromagnetic absorption performance studies at 2-18 GHz indicated stronger attenuation electromagnetic wave ability as compared to other shapes such as spindles, spheres, cubes, and rods. The maximum absorption frequency bandwidth was at 7.2 GHz with a coating thickness d = 1.5 mm. Special structures and the absence of BaCO3 likely played a vital role in the excellent electromagnetic absorption properties described in this research.

Solar heating assisted rapid cleanup of viscous crude oil spills using reduced graphene oxide-coated sponges

The rapid cleanup of heavy crude oil spills is challenging due to the poor mobility of highly viscous oil.Traditional absorption strategies involve heating oils to a relatively high temperature to reduce their viscosity,but this method is expensive.Herein,a solar-heated reduced graphene oxide(rGO)-wrapped melamine sponge(MS)was proposed to rapidly absorb oil.The prepared rGO-MS exhibited good hydrophobicity and oleophilicity and could be used for the rapid cleanup of oil spills from water.In addition,the excellent photothermal conversion effect of rGO enabled the rGO-MS composite to achieve a solar energy absorption efficiency of 91%.Due to the localized solar energy collection and wetting properties of rGO-MS,viscous oil near the contact region was effectively heated,enabling rapid heavy oil recovery under solar light illumination.This proposed solar heating-assisted viscous oil sorbent has great promise for use in heavy oil spill cleanups in the future.

Multi-3D hierarchical biomass-based carbon particles absorber for solar desalination and thermoelectric power generator

To meet challenges of the global energy crisis and the freshwater resources shortage,the interfacial solarto-steam conversion(ISSC)system was developed quickly in recent years.The photothermal materials play an important role in the ISSC system.We are devoted to developing a unique photothermal material integrating multiple 3 D design philosophy both at macroscopic and microscopic levels by employing the cost-effective and widespread resources like straw,rose and coffee grounds,for carbonization as solar absorbers.The biomass-based carbonized particles(CPs)possess three major advantages:(1)wide sizedistribution is accessible to form 3 D porous rough surface of absorber layer to enhance ability of light absorption;(2)the pristine hierarchical microstructure could absorb nearly all the incident light;(3)the intrinsic vascular bundles with pores on their lumen walls provide a rapid and omnidirectional transport for water and steam escape.A high-efficient solar steam device was fabricated based on the absorber material with its internal 3 D micro textures and external 3 D architectures.Under the illumination of 1 sun,the photothermal conversion efficiency of straw,rose and coffee CPs can reach 93.4%,92.8% and 76%,respectively.Simultaneously,a high-efficient solar thermoelectric generator(STEG)is made by coating CPs on a commercial thermoelectric generator and the maximum power of STEG can reach 538.0μW.Such scalable biomass-based photothermal materials and high-grade thermoelectric conversion capability could be applied to the water purification and the electricity production.