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Intensification of heat exchanger performance utilizing nanofluids

International Journal of Thermofluids 2021年 10卷

作者： Maghrabie, Hussein M. Elsaid, Khaled Sayed, Enas Taha Abdelkareem, Mohammad Ali Wilberforce, Tabbi Ramadan, Mohamad Olabi, A.G. Department of Mechanical Engineering Faculty of Engineering South Valley University Qena83521 Egypt Chemical Engineering Program Texas A& M University College StationTX United States Center for Advanced Materials Research University of Sharjah PO Box 27272 Sharjah United Arab Emirates Chemical Engineering Department Minia University Elminia Egypt Department of Sustainable and Renewable Energy Engineering University of Sharjah P.O. Box 27272 Sharjah United Arab Emirates Mechanical Engineering and Design Aston University School of Engineering and Applied Science Aston Triangle BirminghamB4 7ET United Kingdom International University of Beirut PO Box 146404 Beirut Lebanon Associate member at FCLAB CNRS Univ. Bourgogne Franche-Comte Belfort cedex France

Heat exchangers are widely utilized in different thermal systems for diverse industrial aspects. The selection of HEx depends on the thermal efficiency, operating load, size, flexibility in operation, compatibility with working fluids, better temperature and flow controls, and comparatively low capital and maintenance costs. Heat transfer intensification of heat exchangers can be fulfilled using passive, active, or combined approaches. Utilizing nanofluids as working fluids for heat exchangers have evolved recently. The performance of heat exchangers employed different nanofluids depends mainly on the characteristics and improvement of thermophysical properties. Regarding the unique behavior of different nanofluids, researchers have attended noteworthy progress. The current study reviews and summarizes the recent implementations carried out on utilizing nanofluids in different types of heat exchangers, including plate heat exchangers, double-pipe heat exchangers, shell and tube heat exchangers, and cross-flow heat exchangers. The results showed that nanofluids with enhanced thermal conductivity, although accompanied by a considerable decrease in the heat capacity and raising viscosity, has resulted in performance enhancement of different heat exchangers types. So, the performance evaluation criterion that combines the thermal enhancement and increases the pumping power for any type of heat exchangers is requisite to evaluate the overall performance properly. The challenges and opportunities for future work of heat transfer and fluid flow for different types of heat exchangers utilizing nanofluids are discussed and presented. © 2021 The Author(s)

关键词： Heat exchangers

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Effects of sodium alginate-poly(acrylic acid) cross-linked hydrogel beads on soil conditioner in the absence and presence of phosphate and carbonate ions

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Case Studies in Chemical and Environmental engineering 2024年 9卷

作者： Hidayat, Endar Sarbani, Nur Maisarah Mohamad Lahiri, Sudip Kumar Samitsu, Sadaki Yonemura, Seiichiro Mitoma, Yoshiharu Harada, Hiroyuki Graduate School of Comprehensive Scientific Research Program in Biological System Sciences Prefectural University of Hiroshima Shobara 727-0023 Japan Department of Life System Science Faculty of Bioresources Science Prefectural University of Hiroshima Shobara 727-0023 Japan Data-driven Polymer Design Group Research Center for Macromolecules and Biomaterials National Institute for Materials Science 1−2−1 Sengen Tsukuba 305-0047 Japan Department of Mechanical & Industrial Engineering University of Toronto Toronto M5S 3G8 ON Canada Faculty of Allied Health Sciences Chettinad Hospital and Research Institute Chettinad Academy of Research and Education Tamil Nadu Kelambakkam 603103 India

Hydrogel beads, composed of polymers, possess the ability to absorb substantial quantities of water simultaneously and gradually release it in dry conditions. In this work, hydrogel beads were synthesized using sodium alginate (S-Alg) and poly (acrylic acid) (P-Acc), either in the absence or presence of phosphate (PO₄ ³⁻) (S-Alg/P-Acc@PO₄ ³⁻) and carbonate (CO₃ ²⁻) anionic ions (S-Alg/P-Acc@CO₃ ²⁻). Subsequently, these beads were crosslinked with Ca²⁺ ions. The scanning electron microscopy (SEM) images demonstrated that the presence of anionic ions has an impact on the structure of the hydrogel beads and enhances porosity expansion while concurrently reducing the concentration of carboxyl (COOH) groups. The hydrogel beads exhibited a great swelling behavior, with S-Alg/P-Acc@CO₃ ²⁻ capable of absorbing up to 73.5 % of water in acidic conditions, but decreased under neutral and basic conditions. Soil water loss (SWL) experiments confirmed the ability of hydrogel beads to retain water in the soil. Additionally, observations of soil characteristics after a 14-day treatment revealed no significant difference in pH and C/N ratio (P-value <0.05). However, soil's available Fe and N–NO₃ ^- significantly reduced (P-value <0.05) while substantially promoting soil N–NH₄ ⁺, available phosphorus (P), cation exchange capacity (CEC), soil organic carbon (SOC), and exchangeable cation (Ca²⁺, K⁺ and Mg²⁺). The presence of hydroxyl (-OH) and –COOH groups was found to be crucial for enhancing soil properties. © 2024 The Authors

关键词： Anionic ions Hydrogel beads Poly (acrylic acid) Sodium alginate Soil characteristics Soil water retention Swelling

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Signature of multilayer graphene strain-controlled domain walls in quantum Hall effect

arXiv

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arXiv 2020年

作者： Anderson, Paul Huang, Yifan Fan, Yuanjun Qubbaj, Sara Coh, Sinisa Zhou, Qin Ojeda-Aristizabal, Claudia Department of Physics and Astronomy California State University Long Beach Long BeachCA90840 United States Department of Mechanical and Materials Engineering University of Nebraska LincolnNE68588-0526 United States Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside RiversideCA92521 United States

Domain walls, topological defects that define the frontier between regions of different stacking in multilayer graphene, have proved to host exciting physics. The ability of tuning these topological defects in-situ in an electronic transport experiment brings a wealth of possibilities in terms of fundamental understanding of domain walls as well as for electronic applications. Here, we demonstrate through a MEMS (micro-electromechanical system) actuator and magnetoresistance measurements the effect of domain walls in multilayer graphene quantum Hall effect. Reversible and controlled uniaxial strain triggers these topological defects, manifested as new quantum Hall effect plateaus as well as a discrete and reversible modulation of the current across the device. Our findings are supported by theoretical calculations and constitute the first indication of the in-situ tuning of topological defects in multilayer graphene probed through electronic transport, opening the way to the use of reversible topological defects in electronic applications. Copyright © 2020, The Authors. All rights reserved.

关键词： Graphene

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Triple-Layered Carbon-SiO₂ Composite Membrane for High Energy Density and Long Cycling Li-S Batteries

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ACS Nano 2019年第5期13卷 5900-5909页

作者： Kou, Wei Li, Xiangcun Liu, Yang Zhang, Xiaopeng Yang, Shaoran Jiang, Xiaobin He, Gaohong Dai, Yan Zheng, Wenji Yu, Guihua State Key Laboratory of Fine Chemicals Chemical Engineering Department Dalian University of Technology Dalian 116024 China Department of Mechanical and Biomedical Engineering City University of Hong Kong 83 Tat Chee Avenue Hong Kong Hong Kong Materials Science and Engineering Program Department of Mechanical Engineering University of Texas at Austin Austin 78712 TX United States

Here we report a highly scalable yet flexible triple-layer structured porous C/SiO2 membrane via a facile phase inversion method for advancing Li-sulfur battery technology. As a multifunctional current-collector-free ... 详细信息

Here we report a highly scalable yet flexible triple-layer structured porous C/SiO₂ membrane via a facile phase inversion method for advancing Li-sulfur battery technology. As a multifunctional current-collector-free cathode, the conductive dense layer of the C/SiO₂ membrane offers hierarchical macropores as an ideal sulfur host to alleviate the volume expansion of sulfur species and facilitate ion/electrolyte transport for fast kinetics, as well as spongelike pores to enable high sulfur loading. The triple-layer structured membrane cathode enables the filling of most sulfur species in the macropores and additional loading of a thin sulfur slurry on the membrane surface, which facilitates ion/electrolyte transport with faster kinetics than the conventional S/C slurry-based cathode. Furthermore, density functional theory simulations and visual adsorption measurements confirm the critical role of the doped SiO₂ nanoparticles (∼10 nm) in the asymmetric C membrane in suppressing the shuttle effect of polysulfides via chemisorption and electrocatalysis. The rationally designed C/SiO₂ membrane cathodes demonstrate long-term cycling stability of 300 cycles at a high sulfur loading of 2.8 mg cm^-2 with a sulfur content of ∼75%. This scalable yet flexible self-supporting cathode design presents a useful strategy for realizing practical applications of high-performance Li-S batteries. © 2019 American Chemical Society.

关键词： C/SiO2 membrane energy storage Li-S batteries multifunctional phase-inversion

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Thousand-fold increase in plasmonic light emission via combined electronic and optical Excitations

arXiv

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arXiv 2021年

作者： Cui, Longji Zhu, Yunxuan Nordlander, Peter Di Ventra, Massimiliano Natelson, Douglas Department of Physics and Astronomy and Smalley-Curl Institute Rice University HoustonTX77005 United States Paul M. Rady Department of Mechanical Engineering University of Colorado BoulderCO80309 United States Materials Science and Engineering Program University of Colorado BoulderCO80309 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Physics University of California San Diego San DiegoCA92093 United States

Surface plasmon enhanced processes and hot-carrier dynamics in plasmonic nanostructures are of great fundamental interest to reveal light-matter interactions at the nanoscale. Using plasmonic tunnel junctions as a platform supporting both electrically-and optically excited localized surface plasmons, we report a much greater (over 1000×) plasmonic light emission at upconverted photon energies under combined electro-optical excitation, compared with electrical or optical excitation separately. Two mechanisms compatible with the form of the observed spectra are interactions of plasmon-induced hot carriers and electronic anti-Stokes Raman scattering. Our measurement results are in excellent agreement with a theoretical model combining electro-optical generation of hot carriers through non-radiative plasmon excitation and hot-carrier relaxation. We also discuss the challenge of distinguishing relative contributions of hot carrier emission and the anti-Stokes electronic Raman process. This observed increase in above-threshold emission in plasmonic systems may open avenues in on-chip nanophotonic switching and hot carrier photocatalysis. © 2021, CC BY-NC-SA.

关键词： Tunnel junctions

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Hybrid Vesicles Enable Mechano-Responsive Hydrogel Degradation

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Angewandte Chemie 2023年第41期135卷

作者： Sung-Won Hwang Chung-Man Lim Prof. Cong Truc Huynh Hossein Moghimianavval Prof. Nicholas A. Kotov Prof. Eben Alsberg Prof. Allen P. Liu Department of Chemical Engineering University of Michigan Ann Arbor MI 48109 USA Department of Materials Science and Engineering University of Michigan Ann Arbor MI 48109 USA Department of Biomedical Engineering University of Illinois Chicago Chicago IL 60612 USA Department of Mechanical Engineering University of Michigan Ann Arbor MI 48109 USA Departments of Biomedical Engineering Macromolecular Science and Engineering Biointerfaces Institute University of Michigan Ann Arbor MI 48109 USA Departments of Orthopedic Surgery Pharmacology and Regenerative Medicine and Mechanical and Industrial Engineering University of Illinois Chicago Chicago IL 60612 USA Departments of Biomedical Engineering Biophysics Cellular and Molecular Biology Program Applied Physics Program University of Michigan Ann Arbor MI 48109 USA

Stimuli-responsive hydrogels are intriguing biomimetic materials. Previous efforts to develop mechano-responsive hydrogels have mostly relied on chemical modifications of the hydrogel structures. Here, we present a simple, generalizable strategy that confers mechano-responsive behavior on hydrogels. Our approach involves embedding hybrid vesicles, composed of phospholipids and amphiphilic block copolymers, within the hydrogel matrix to act as signal transducers. Under mechanical stress, these vesicles undergo deformation and rupture, releasing encapsulated compounds that can control the hydrogel network. To demonstrate this concept, we embedded vesicles containing ethylene glycol tetraacetic acid (EGTA), a calcium chelator, into a calcium-crosslinked alginate hydrogel. When compressed, the released EGTA sequesters calcium ions and degrades the hydrogel. This study provides a novel method for engineering mechano-responsive hydrogels that may be useful in various biomedical applications.

关键词： Block Copolymers Functional Material Stimuli-Responsive Hydrogel Stress-Induced Degradation Vesicles

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Unraveling the Cr 2 N Precipitation and Its Negative Effect on the Corrosion Resistance of Friction Stir Welded UNS S32760 Super Duplex Stainless Steel

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Surfaces and Interfaces 2025年 71卷

作者： G.S. Vacchi W.S. de Carvalho C.P. Meinhardt L.A. Bergmann S.T. Amancio-Filho C.A.D. Rovere Munir Rachid Corrosion Laboratory Department of Materials Engineering Federal University of São Carlos Rodovia Washington Luis Km 235 São Carlos SP 13565-905 Brazil Graduate Program in Materials Science and Engineering Federal University of São Carlos Brazil Institute of Materials Science Joining and Forming BMK Endowed Professorship for Aviation Graz University of Technology – TU Graz Kopernikusgasse 24/1 Graz 8010 Austria Department of Mechanical Engineering Federal University of Pampa Avenida Tiarajú 810 Alegrete RS Brazil Helmholtz-Zentrum Hereon Institute of Materials Mechanics Solid State Materials Processing Max-Planck-Straße 1 Geesthacht Germany

The root surface of a friction stir welded super duplex stainless steel (UNS S32760) was thoroughly characterized in this study. The findings revealed a refined grain structure and a conspicuous increase of 50 HV 0.3 in the Root’s hardness. Interestingly, the volume fraction of the ferrite phase remained largely unchanged. Rapid cooling in the welding process led to the Cr 2 N precipitation at the ferrite/ferrite grain boundaries in the root area, significantly increasing sensitization, reducing localized corrosion resistance under high electrode potentials in a neutral pH saline environment, and adversely affecting root passivity in a hydrochloric acid environment compared to the base metal.

关键词： Friction stir welding Localized corrosion Polarization Sensitization Super duplex stainless steel

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Hybrid Electrolyte engineering Enables Safe and Wide-Temperature Redox Flow Batteries

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Angewandte Chemie 2021年第27期133卷

作者： Leyuan Zhang Prof. Guihua Yu Materials Science and Engineering Program and Department of Mechanical Engineering The University of Texas at Austin Austin TX 78712 USA

Electrolyte is an important component in redox flow batteries (RFBs) that determines the current capability, potential window, and safety, but both aqueous and nonaqueous electrolytes have their intrinsic limits. Here, we develop the proof-of-concept hybrid electrolyte chemistry to enable the design of safe and wide-temperature RFBs. In addition to the non-flammable characteristics, the hybrid electrolyte also inherits the high electrochemical stability and wide operational temperature range. It can show a potential window of 2.5 V and maintain high ion conductivities at low temperatures. It also enables LiI to achieve high Coulombic efficiencies of >99.9 %, showing long cycling stability over 800 cycles. Moreover, it enables the successful operation of Zn/LiI RFBs at −20 °C for 150 cycles with nearly no capacity loss. This study highlights the great potential of hybrid electrolyte chemistry for the approach of safe and high-performance large-scale energy storage systems in wide temperature ranges.

关键词： electrolyte chemistry energy storage hybrid electrolyte redox flow batteries wide temperature range

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Temperature-dependent crystal structure of U3Si2 by high-temperature neutron diffraction 14

Temperature-dependent crystal structure of U3Si2 by high-tem...

引用

14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water Reactor Fuel Performance Conference, TOP FUEL 2019

作者： Vogel, Sven C. Wilson, Tashiema L. Wood, Elizabeth Sooby White, Joshua T. Besmann, Theodore M. Materials Science and Technology Division Los Alamos National Laboratory MS H805 Los AlamosNM87545 United States Mechanical Engineering Department Nuclear Engineering Program University of South Carolina 541 Main St ColumbiaSC29201 United States Department of Physics and Astronomy College of Sciences University of Texas at San Antonio One UTSA Circle San AntonioTX78249 United States

The crystal structure of the U3Si2 line compound in the U-Si system was investigated as a function of temperature from room temperature to 1373 K using high temperature neutron time-of-flight diffraction on the High-pressure Pressure/preferred Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron science Center (LANSCE). The U-Si system is actively researched due to its promise as an accident tolerant nuclear fuel. The simultaneous Rietveld refinement of five histograms from the five HIPPO detector rings provided fundamental datasets for the lattice parameters, anisotropic atomic displacement parameters, and atomic positions as a function of temperature. To explore the possibility of a homogeneity range, two samples were analyzed, stoichiometric U3Si2.00 and a hyperstoichiometric U3Si2.01. While minor differences in the thermal expansion anisotropic atomic displacement parameters between the two samples were observed, over the entire investigated temperature range no additional phases were observed. However, significant differences in the thermal expansion behavior were identified between the two compositions that warrant future investigations. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water Reactor Fuel Performance *** rights reserved.

关键词： Atoms

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Atomic-Scale Dynamics of the Initial Stages of Cu and Cu Alloy Oxidation

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Microscopy and Microanalysis 2024年第SUPPLEMENT_1期30卷

作者： Yang, Judith C Li, Meng Zakharov, Dmitri N McEver, Jack Greene Qiao, Linna Qu, Xiaohui Lu, Deyu Curnan, Matthew T House, Stephen D Gleason, Samuel Ciston, Jim Zhou, Guangwen Saidi, Wissam A Chemical and Petroleum Engineering Department University of Pittsburgh Pittsburgh PA United States Physics and Astronomy Department University of Pittsburgh Pittsburgh PA United States Center for Functional Nanomaterials Brookhaven National Lab Upton NY United States Materials Science and Engineering Program & Department of Mechanical Engineering State University of New York at Binghamton Binghamton NY United States Chemical Engineering Department Pohang University of Science and Technology (POSTECH) Pohang Gyeongbuk Republic of Korea Center for Integrated Nanotechnologies Sandia National Laboratories Albuquerque NM United States Chemistry Department University of California Berkeley CA United States National Center for Electron Microscopy The Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA United States Mechanical Engineering and Materials Science Department University of Pittsburgh Pittsburgh PA United States National Energy Technology Laboratory Pittsburgh PA United States

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