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Effect of light scattering on the performance of a direct absorption solar collector

Kwang Hyun WON, Bong Jae LEE

《能源前沿(英文)》 2018年 第12卷 第1期   页码 169-177 doi: 10.1007/s11708-018-0527-5

摘要: Recently, a solar thermal collector often employs nanoparticle suspension to absorb the solar radiation directly by a working fluid as well as to enhance its thermal performance. The collector efficiency of a direct absorption solar collector (DASC) is very sensitive to optical properties of the working fluid, such as absorption and scattering coefficients. Most of the existing studies have neglected particle scattering by assuming that the size of nanoparticle suspension is much smaller than the wavelength of solar radiation (i.e., Rayleigh scattering is applicable). If the nanoparticle suspension is made of metal, however, the scattering cross-section of metallic nanoparticles could be comparable to their absorption cross-section depending on the particle size, especially when the localized surface plasmon (LSP) is excited. Therefore, for the DASC utilizing a plasmonic nanofluid supporting the LSP, light scattering from metallic particle suspension must be taken into account in the thermal analysis. The present study investigates the scattering effect on the thermal performance of the DASC employing plasmonic nanofluid as a working fluid. In the analysis, the Monte Carlo method is employed to numerically solve the radiative transfer equation considering the volume scattering inside the nanofluid. It is found that the light scattering can improve the collector performance if the scattering coefficient of nanofluid is carefully engineered depending on its value of the absorption coefficient.

关键词: direct absorption solar collector     plasmonic nanofluid     light scattering    

基于超构表面等离激元透镜的高速并行近场直写纳米光刻系统 Article

胡跃强, 李苓, 王榕, 宋剑, 王鸿栋, 段辉高, 纪佳馨, 孟永钢

《工程(英文)》 2021年 第7卷 第11期   页码 1623-1630 doi: 10.1016/j.eng.2020.08.019

摘要:

具有简单、高效、低成本和高灵活性等特点的纳米加工技术在纳米尺度基础研究和原型验证中不可或缺。研究已证明,采用表面等离激元的近场光刻技术(即等离激元光刻)是一种有前景的解决方案。基于高速旋转基底上高刚度被动纳米间隙控制的加工系统是其中一种高效率加工方案。但是,为了研发出新一代具有高分辨率且可靠高效的纳米加工技术,需要探索一种更小更稳定的纳米间隙和新型等离激元透镜及其并行加工方案。因此,本文设计了一套并行等离激元直写纳米光刻系统。该系统应用了新型等离子浮动磁头,当转速为8~18 m⋅s−1时,其最小飞行高度可实现15 nm并且具有高平行度。本文还研制了一种多级的基于超构表面的偏振不敏感等离激元透镜。与传统的等离激元透镜相比,该透镜耦合的功率更大,焦点的范围更集中。该原型系统实现了约26 nm最小线宽的纳米结构并行光刻。该系统有望应用于高自由级、低成本的纳米加工技术,如平面光学元件和纳米机电系统。

 

关键词: 纳米加工     表面等离激元     光刻     等离子体飞行头     超构表面    

Plasmonic Au nanoparticles supported on both sides of TiO2 hollow spheres for maximising photocatalytic

Jianwei Lu, Lan Lan, Xiaoteng Terence Liu, Na Wang, Xiaolei Fan

《化学科学与工程前沿(英文)》 2019年 第13卷 第4期   页码 665-671 doi: 10.1007/s11705-019-1815-2

摘要: A strategy of intensifying the visible light harvesting ability of anatase TiO hollow spheres (HSs) was developed, in which both sides of TiO HSs were utilised for stabilising Au nanoparticles (NPs) through the sacrificial templating method and convex surface-induced confinement. The composite structure of single Au NP yolk-TiO shell-Au NPs, denoted as Au@Au(TiO , was rendered and confirmed by the transmission electron microscopy analysis. Au@Au(TiO showed enhanced photocatalytic activity in the degradation of methylene blue and phenol in aqueous phase under visible light surpassing that of other reference materials such as Au(TiO by 77% and Au@P25 by 52%, respectively, in phenol degradation.

关键词: TiO2 hollow spheres     plasmonic Au nanoparticles     confinement     visible light     photocatalytic degradation    

A review on the application of nanofluids in enhanced oil recovery

《化学科学与工程前沿(英文)》 2022年 第16卷 第8期   页码 1165-1197 doi: 10.1007/s11705-021-2120-4

摘要: Enhanced oil recovery (EOR) has been widely used to recover residual oil after the primary or secondary oil recovery processes. Compared to conventional methods, chemical EOR has demonstrated high oil recovery and low operational costs. Nanofluids have received extensive attention owing to their advantages of low cost, high oil recovery, and wide applicability. In recent years, nanofluids have been widely used in EOR processes. Moreover, several studies have focused on the role of nanofluids in the nanofluid EOR (N-EOR) process. However, the mechanisms related to N-EOR are unclear, and several of the mechanisms established are chaotic and contradictory. This review was conducted by considering heavy oil molecules/particle/surface micromechanics; nanofluid-assisted EOR methods; multiscale, multiphase pore/core displacement experiments; and multiphase flow fluid-solid coupling simulations. Nanofluids can alter the wettability of minerals (particle/surface micromechanics), oil/water interfacial tension (heavy oil molecules/water micromechanics), and structural disjoining pressure (heavy oil molecules/particle/surface micromechanics). They can also cause viscosity reduction (micromechanics of heavy oil molecules). Nanofoam technology, nanoemulsion technology, and injected fluids were used during the EOR process. The mechanism of N-EOR is based on the nanoparticle adsorption effect. Nanoparticles can be adsorbed on mineral surfaces and alter the wettability of minerals from oil-wet to water-wet conditions. Nanoparticles can also be adsorbed on the oil/water surface, which alters the oil/water interfacial tension, resulting in the formation of emulsions. Asphaltenes are also adsorbed on the surface of nanoparticles, which reduces the asphaltene content in heavy oil, resulting in a decrease in the viscosity of oil, which helps in oil recovery. In previous studies, most researchers only focused on the results, and the nanoparticle adsorption properties have been ignored. This review presents the relationship between the adsorption properties of nanoparticles and the N-EOR mechanisms. The nanofluid behaviour during a multiphase core displacement process is also discussed, and the corresponding simulation is analysed. Finally, potential mechanisms and future directions of N-EOR are proposed. The findings of this study can further the understanding of N-EOR mechanisms from the perspective of heavy oil molecules/particle/surface micromechanics, as well as clarify the role of nanofluids in multiphase core displacement experiments and simulations. This review also presents limitations and bottlenecks, guiding researchers to develop methods to synthesise novel nanoparticles and conduct further research.

关键词: nanofluid     EOR mechanism     nanoparticle adsorption     interface property     internal property    

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological lubricant

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0720-4

摘要: Aerospace aluminum alloy is the most used structural material for rockets, aircraft, spacecraft, and space stations. The deterioration of surface integrity of dry machining and the insufficient heat transfer capacity of minimal quantity lubrication have become the bottleneck of lubrication and heat dissipation of aerospace aluminum alloy. However, the excellent thermal conductivity and tribological properties of nanofluids are expected to fill this gap. The traditional milling force models are mainly based on empirical models and finite element simulations, which are insufficient to guide industrial manufacturing. In this study, the milling force of the integral end milling cutter is deduced by force analysis of the milling cutter element and numerical simulation. The instantaneous milling force model of the integral end milling cutter is established under the condition of dry and nanofluid minimal quantity lubrication (NMQL) based on the dual mechanism of the shear effect on the rake face of the milling cutter and the plow cutting effect on the flank surface. A single factor experiment is designed to introduce NMQL and the milling feed factor into the instantaneous milling force coefficient. The average absolute errors in the prediction of milling forces for the NMQL are 13.3%, 2.3%, and 7.6% in the x-, y-, and z-direction, respectively. Compared with the milling forces obtained by dry milling, those by NMQL decrease by 21.4%, 17.7%, and 18.5% in the x-, y-, and z-direction, respectively.

关键词: milling     force     nanofluid minimum quantity lubrication     aerospace aluminum alloy     nano biological lubricant    

Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication based on molecular dynamic simulation

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0733-z

摘要: Carbon group nanofluids can further improve the friction-reducing and anti-wear properties of minimum quantity lubrication (MQL). However, the formation mechanism of lubrication films generated by carbon group nanofluids on MQL grinding interfaces is not fully revealed due to lack of sufficient evidence. Here, molecular dynamic simulations for the abrasive grain/workpiece interface were conducted under nanofluid MQL, MQL, and dry grinding conditions. Three kinds of carbon group nanoparticles, i.e., nanodiamond (ND), carbon nanotube (CNT), and graphene nanosheet (GN), were taken as representative specimens. The [BMIM]BF4 ionic liquid was used as base fluid. The materials used as workpiece and abrasive grain were the single-crystal Ni–Fe–Cr series of Ni-based alloy and single-crystal cubic boron nitride (CBN), respectively. Tangential grinding force was used to evaluate the lubrication performance under the grinding conditions. The abrasive grain/workpiece contact states under the different grinding conditions were compared to reveal the formation mechanism of the lubrication film. Investigations showed the formation of a boundary lubrication film on the abrasive grain/workpiece interface under the MQL condition, with the ionic liquid molecules absorbing in the groove-like fractures on the grain wear’s flat face. The boundary lubrication film underwent a friction-reducing effect by reducing the abrasive grain/workpiece contact area. Under the nanofluid MQL condition, the carbon group nanoparticles further enhanced the tribological performance of the MQL technique that had benefited from their corresponding tribological behaviors on the abrasive grain/workpiece interface. The behaviors involved the rolling effect of ND, the rolling and sliding effects of CNT, and the interlayer shear effect of GN. Compared with the findings under the MQL condition, the tangential grinding forces could be further reduced by 8.5%, 12.0%, and 14.1% under the diamond, CNT, and graphene nanofluid MQL conditions, respectively.

关键词: grinding     minimum quantity lubrication     carbon group nanofluid     tribological mechanism    

Micro/nanofluidics-enabled energy conversion and its implemented devices

Yang YANG, Jing LIU

《能源前沿(英文)》 2011年 第5卷 第3期   页码 270-287 doi: 10.1007/s11708-010-0126-6

摘要: Most people were not aware of the role of energy as a basic force that drives the development and economic growth of the world until the two great oil crises occurred. According to the conservation law, energy not only exists in various forms but is also capable of being converted from one form to another. The common forms of energy are mechanical energy, chemical energy, internal energy, electrical energy, atomic energy, and electromagnetic energy, among others. The fluids in nature serve as the most common carriers and media in the energy conversion process. Following the rapid development of microelectromechanical systems (MEMS) technology, the energy supply and conversion issue in micro/nano scale has also been introduced in research laboratories worldwide. With unremitting efforts, great quantities of micro/nano scale energy devices have been investigated. Micro/nanofluid shows distinct features in transporting and converting energy similar to their counterpart macroscale tasks. In this paper, a series of micro/nanofluid-enabled energy conversion devices is reviewed based on the transformation between different forms of energy. The evaluation and contradistinction of their performances are also examined. The role of micro/nanofluid as media in micro/nano energy devices is summarized. This contributes to the establishment of a comprehensive and systematic structure in the relationship between energy conversion and fluid in the micro/nano scale. Some fundamental and practical issues are outlined, and the prospects in this challenging area are explored.

关键词: micro/nanofluid     different energy forms     energy conversion     medium role    

From plasma to plasmonics: toward sustainable and clean water production through membranes

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 1809-1836 doi: 10.1007/s11705-023-2339-3

摘要: The increasing demand for potable water is never-ending. Freshwater resources are scarce and stress is accumulating on other alternatives. Therefore, new technologies and novel optimization methods are developed for the existing processes. Membrane-based processes are among the most efficient methods for water treatment. Yet, membranes suffer from severe operational problems, namely fouling and temperature polarization. These effects can harm the membrane’s permeability, permeate recovery, and lifetime. To mitigate such effects, membranes can be treated through two techniques: plasma treatment (a surface modification technique), and treatment through the use of plasmonic materials (surface and bulk modification). This article showcases plasma- and plasmonic-based treatments in the context of water desalination/purification. It aims to offer a comprehensive review of the current developments in membrane-based water treatment technologies along with suggested directions to enhance its overall efficiency through careful selection of material and system design. Moreover, basic guidelines and strategies are outlined on the different membrane modification techniques to evaluate its prerequisites. Besides, we discuss the challenges and future developments about these membrane modification methods.

关键词: water treatment     membrane-based process     plasma treatment     plasma polymerization     plasmonic     light-to-heat conversion    

Application of different CFD multiphase models to investigate effects of baffles and nanoparticles on heat transfer enhancement

Ali SHAHMOHAMMADI,Arezou JAFARI

《化学科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 320-329 doi: 10.1007/s11705-014-1437-7

摘要: In this work, the effect of baffles in a pipe on heat transfer enhancement was studied using computational fluid dynamics (CFD) in the presence of Al O nanoparticles which are dispersed into water. Fluid flow through the horizontal tube with uniform heat flux was simulated numerically and three dimensional governing partial differential equations were solved. To find an accurate model for CFD simulations, the results obtained by the single phase were compared with those obtained by three different multiphase models including Eulerian, mixture and volume of fluid (VOF) at Reynolds numbers in range of 600 to 3000, and two different nanoparticle concentrations (1% and 1.6%). It was found that multiphase models could better predict the heat transfer in nanofluids. The effect of baffles on heat transfer of nanofluid flow was also investigated through a baffled geometry. The numerical results show that at Reynolds numbers in the range of 600 to 2100, the heat transfer of nanofluid flowing in the geometry without baffle is greater than that of water flowing through a tube with baffle, whereas the difference between these effects (nanofluid and baffle) decreases with increasing the Reynolds number. At higher Reynolds numbers (2100–3000) the baffle has a greater effect on heat transfer enhancement than the nanofluid.

关键词: CFD simulation     heat transfer     nanofluid     baffle     single phase model     multiphase model    

grown TiN/N-TiO composite for enhanced photocatalytic H evolution activity

《能源前沿(英文)》 2021年 第15卷 第3期   页码 721-731 doi: 10.1007/s11708-021-0766-8

摘要: Titanium nitride (TiN) decorated N-doped titania (N-TiO2) composite (TiN/N-TiO2) is fabricated via an in situ nitridation using a hydrothermally synthesized TiO2 and melamine (MA) as raw materials. After the optimization of the reaction condition, the resultant TiN/N-TiO2 composite delivers a hydrogen evolution activity of up to 703 μmol/h under the full spectrum irradiation of Xe-lamp, which is approximately 2.6 and 32.0 times more than that of TiO2 and TiN alone, respectively. To explore the underlying photocatalytic mechanism, the crystal phase, morphology, light absorption, energy band structure, element composition, and electrochemical behavior of the composite material are characterized and analyzed. The results indicate that the superior activity is mainly caused by the in situ formation of plasmonic TiN and N-TiO2 with intimate interface contact, which not only extends the spectral response range, but also accelerates the transfer and separation of the photoexcited hot charge carrier of TiN. The present study provides a fascinating approach to in situ forming nonmetallic plasmonic material/N-doped TiO2 composite photocatalysts for high-efficiency water splitting.

关键词: photocatalytic H2 evolution     TiN/N-TiO2 composite     plasmonic effect     in-situ nitridation    

Plasmonic light trapping for enhanced light absorption in film-coupled ultrathin metamaterial thermophotovoltaic

Qing NI, Hassan ALSHEHRI, Yue YANG, Hong YE, Liping WANG

《能源前沿(英文)》 2018年 第12卷 第1期   页码 185-194 doi: 10.1007/s11708-018-0522-x

摘要: Ultrathin cells have gained increasing attention due to their potential for reduced weight, reduced cost and increased flexibility. However, the light absorption in ultrathin cells is usually very weak compared to the corresponding bulk cells. To achieve enhanced photon absorption in ultrathin thermophotovoltaic (TPV) cells, this work proposed a film-coupled metamaterial structure made of nanometer-thick gallium antimonide (GaSb) layer sandwiched by a top one-dimensional (1D) metallic grating and a bottom metal film. The spectral normal absorptance of the proposed structure was calculated using the rigorous coupled-wave algorithm (RCWA) and the absorption enhancement was elucidated to be attributed to the excitations of magnetic polariton (MP), surface plasmon polariton (SPP), and Fabry-Perot (FP) resonance. The mechanisms of MP, SPP, and FP were further confirmed by an inductor-capacitor circuit model, dispersion relation, and phase shift, respectively. Effects of grating period, width, spacer thickness, as well as incidence angle were discussed. Moreover, short-circuit current density, open-circuit voltage, output electric power, and conversion efficiency were evaluated for the ultrathin GaSb TPV cell with a film-coupled metamaterial structure. This work will facilitate the development of next-generation low-cost ultrathin infrared TPV cells.

关键词: metamaterial     thermophotovoltaic     plasmonics     light trapping     selective absorption    

Magnetic-porous microspheres with synergistic catalytic activity of small-sized gold nanoparticles and titania matrix

Kadriye Özlem Hamaloğlu, Ebru Sağ, Çiğdem Kip, Erhan Şenlik, Berna Saraçoğlu Kaya, Ali Tuncel

《化学科学与工程前沿(英文)》 2019年 第13卷 第3期   页码 574-585 doi: 10.1007/s11705-019-1799-y

摘要: Fe O nanoparticles immobilized on porous titania in micron-size range were decorated with small-sized gold nanoparticles and used as a plasmonic catalyst for the reduction of 4-nitrophenol. Monodisperse-porous magnetic titania microspheres were synthesized with bimodal pore-size distribution by the sol-gel templating method. Small-sized gold nanoparticles obtained by the Martin method were attached onto the aminated form of the magnetic titania microspheres. A significant enhancement in the catalytic activity was observed using the gold nanoparticle-decorated magnetic titania microspheres compared to gold nanoparticle-decorated magnetic silica microspheres because of the synergistic effect between small-sized gold nanoparticles and titania. The synergistic effect for gold nanoparticle-attached magnetic titania microspheres could be explained by surface plasmon resonance-induced transfer of hot electrons from gold nanoparticles to the conduction band of titania. Using the proposed catalyst, 4-nitrophenol could be converted to 4-aminophenol in an aqueous solution within 0.5 min. The 4-nitrophenol reduction rates were 2.5–79.3 times higher than those obtained with similar plasmonic catalysts. The selection of micron-size, magnetic, and porous titania microspheres as a support material for the immobilization of small-sized gold nanoparticles provided a recoverable plasmonic catalyst with high reduction ability.

关键词: small-sized gold nanoparticles     magnetic titania microspheres     sol-gel template synthesis     plasmonic catalysis     4-nitrophenol    

用于提高叔胺的二氧化碳吸收能力的纳米多孔碳材料促进剂的制备 Review

Masood S. Alivand, Omid Mazaheri, Yue Wu, Geoffrey W. Stevens, Colin A. Scholes, Kathryn A. Mumford

《工程(英文)》 2020年 第6卷 第12期   页码 1381-1394 doi: 10.1016/j.eng.2020.05.004

摘要:

叔胺水溶液具有吸收力强、反应热低、腐蚀性低等特点,作为一种二氧化碳(CO2)吸收剂,其应用前景良好。然而,由于叔胺吸收CO2的速率过慢,不适用于大规模实际应用。本文对一些不同特性的纳米多孔碳材料促进剂(NCP)进行了合成和表征,并将其作为N,N-二乙基乙醇胺(DEEA)水溶液吸收CO2的加速剂。通过采用超声技术将NCP注入到3 mol·L–1的DEEA水溶液中,制备得 到了DEEA-NCP纳米流体。结果表明,在与乙二胺(EDA)、聚乙烯亚胺(PEI)发生官能化反应的微孔(GC)碳材料和介孔(GS)碳材料结构中,GC-EDA促进剂的性能最佳。对比DEEAGC-EDA纳米流体与典型的DEEA水溶液得出,GC-EDA促进剂在40℃时的CO2吸收率为36.8~50.7 kPa·min–1,提高了38.6%,平衡CO2吸收率为每摩尔DEEA中CO2的含量为0.69~0.78 mol(15 kPa; 40 ℃),提高了13.2%。此外,本文测定了DEEA-GC-EDA纳米流体的可再利用性,同时还提出了循环利用的方法。本文得出结论:在叔胺中加入NCP-GC-EDA促进剂可以提高CO2吸收率,同时还有利于实现叔胺的大规模使用,其前景广阔。 

关键词: 二氧化碳吸收     纳米流体     N     N-二乙基乙醇胺     纳米多孔碳促进剂     聚胺功能化    

标题 作者 时间 类型 操作

Effect of light scattering on the performance of a direct absorption solar collector

Kwang Hyun WON, Bong Jae LEE

期刊论文

基于超构表面等离激元透镜的高速并行近场直写纳米光刻系统

胡跃强, 李苓, 王榕, 宋剑, 王鸿栋, 段辉高, 纪佳馨, 孟永钢

期刊论文

Plasmonic Au nanoparticles supported on both sides of TiO2 hollow spheres for maximising photocatalytic

Jianwei Lu, Lan Lan, Xiaoteng Terence Liu, Na Wang, Xiaolei Fan

期刊论文

A review on the application of nanofluids in enhanced oil recovery

期刊论文

Mechanical behavior and semiempirical force model of aerospace aluminum alloy milling using nano biological lubricant

期刊论文

Tribological mechanism of carbon group nanofluids on grinding interface under minimum quantity lubrication based on molecular dynamic simulation

期刊论文

Micro/nanofluidics-enabled energy conversion and its implemented devices

Yang YANG, Jing LIU

期刊论文

From plasma to plasmonics: toward sustainable and clean water production through membranes

期刊论文

Application of different CFD multiphase models to investigate effects of baffles and nanoparticles on heat transfer enhancement

Ali SHAHMOHAMMADI,Arezou JAFARI

期刊论文

grown TiN/N-TiO composite for enhanced photocatalytic H evolution activity

期刊论文

Plasmonic light trapping for enhanced light absorption in film-coupled ultrathin metamaterial thermophotovoltaic

Qing NI, Hassan ALSHEHRI, Yue YANG, Hong YE, Liping WANG

期刊论文

Magnetic-porous microspheres with synergistic catalytic activity of small-sized gold nanoparticles and titania matrix

Kadriye Özlem Hamaloğlu, Ebru Sağ, Çiğdem Kip, Erhan Şenlik, Berna Saraçoğlu Kaya, Ali Tuncel

期刊论文

用于提高叔胺的二氧化碳吸收能力的纳米多孔碳材料促进剂的制备

Masood S. Alivand, Omid Mazaheri, Yue Wu, Geoffrey W. Stevens, Colin A. Scholes, Kathryn A. Mumford

期刊论文