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Numerical Investigations on Fluid Flow and Heat Transfer Characteristics of an Ultra-Thin Heat Pipe with Separated Wick Structures

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Frontiers in Heat and Mass Transfer 2024年第3期22卷 869-887页

作者： Yasushi Koito Akira Fukushima Division of Industrial Fundamentals Faculty of Advanced Science and TechnologyKumamoto UniversityKumamoto860-8555Japan Department of Mechanical and Mathematical Engineering Graduate School of Science and TechnologyKumamoto UniversityKumamoto860-8555Japan

Thermal and fluid-flow characteristics were numerically analyzed for ultra-thin heat *** studies have been conducted for ultra-thin heat pipes with a centered wick structure,but this study focused on separated wick structures to increase the evaporation/condensation surface areas within the heat pipe and to reduce the concentration of heat flux within the wick structure.A mathematical heat-pipe model was made in the threedimensional coordinate system,and the model consisted of three regions:a vapor channel,liquid-wick,and container wall *** conservation equations for mass,momentum,and energy were solved numerically with boundary conditions by using a code developed by one of the *** numerical results with the separated wick structures were compared with those with the centered,which confirmed the effectiveness of the separation of the wick ***,the effectiveness of the separation was affected by the position of the separated wick structure.A simple equation was presented to determine the optimum position of the separated wick *** analyses were also conducted when the width of the heat pipe was increased with the cooled section,which clarified that the increase in the cooled-section width with the addition of wick structures wasmore effective than the increase in the cooled-section length.A 44%reduction in the total temperature difference of the heat pipe was obtained under the present numerical ***,a comparison wasmade between experimental results and numerical results.

关键词： Ultra-thin heat pipe vapor chamber heat transfer surface CFD thermal design

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Experimental Analyses of Flow Pattern and Heat Transfer in a Horizontally Oriented Polymer Pulsating Heat Pipe withMerged Liquid Slugs

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Frontiers in Heat and Mass Transfer 2024年第5期22卷 1381-1397页

作者： Zhengyuan Pei Yasushi Koito Department of Mechanical and Mathematical Engineering Graduate School of Science and TechnologyKumamoto UniversityKumamoto860-8555Japan Division of Industrial Fundamentals Faculty of Advanced Science and TechnologyKumamoto UniversityKumamoto860-8555Japan

Extended experiments were conducted on the oscillation characteristics of merged liquid slugs in a horizontally oriented polymer pulsating heat pipe(PHP).The PHP’s serpentine channel comprised 14 parallel channels with a width of 1.3 mm and a height of 1.1 *** evaporator and condenser sections were 25 and 50 mm long,respectively,and the adiabatic section in between was *** a plastic 3D printer and semi-transparent filament made from acrylonitrile butadiene styrene,the serpentine channel was printed directly onto a thin polycarbonate sheet to form the *** PHP was charged with *** the experiments,the evaporator section was heated,and the condenser section was cooled using high-temperature and low-temperature thermostatic baths,*** patterns of the working fluid were obtained with temperature distributions of the PHP.A mathematical model was developed to analyze the flow *** liquid slugs were observed in every two channels,and their oscillation characteristics were found to be approximately the same in time and *** was also found that the oscillations of the merged liquid slugs became slower,but the heat transfer rate of the PHP increased with a decrease in the filling ratio of the working *** is because vapor condensation was enhanced in vapor plugs as the filling ratio ***,the filling ratio had a lower limit,and the heat transfer rate was maximum when the filling ratio was 40.6%in the present experimental range.

关键词： Pulsating heat pipe polymer heat pipe visualization experiment flow pattern analysis heat transfer enhancement

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Lignin derived absorbent for efficient and sustainable CO_(2) capture

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Chinese Journal of Chemical engineering 2023年第2期54卷 89-97页

作者： Yuandong Cui Bin He Yu Lei Yu Liang Wanting Zhao Jian Sun Xiaomin Liu School of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China School of Life Science Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering Ministry of Industry and Information TechnologyBeijing Engineering Research Center of Cellulose and Its DerivativesAdvanced Research Institute of Multidisciplinary ScienceBeijing Institute of TechnologyBeijing 100081China

High and cost-efficient capture of CO_(2) is a prerequisite and an inevitable path of carbon emission reduction. To address the challenges(high cost, low efficiency, less sustainability, etc.) of existing petroleum-based CO_(2) absorbents, herein, a class of efficient and sustainable lignin-based absorbents were resoundingly prepared by grafting the active amine group on a lignin derived compound vanillin and alkali lignin. The results demonstrated that vanillin modified by acrylamide achieved the excellent absorption capacity among the three absorbents, whose ability was 0.114 g CO_(2) per gram of absorbent under 25 ℃ and 100 kPa. In addition, the absorbent retained stable absorbability of CO_(2) after 6 *** absorbing capacity of the absorbent formed by the coupling of vanillin and acrylamide to CO_(2) was much greater than their own(i.e. 0 g CO_(2) ·g^(-1)vanillin, 0.01 g CO_(2) ·g^(-1) acrylamide, respectively).Detailed information revealed the multi-site synergistic absorption mechanism, in which CO_(2) has C and O double interactions with the amide group of the absorbent, and single interaction with the hydroxyl oxygen on the benzene ring of the absorbent. The absorption capacity of modified lignin for CO_(2) is as high as 0.12 g CO_(2) per gram of absorbent, which is comparable with that of model compound *** work not only provides a new idea for the design of bio-absorbents for CO_(2) capture, but explores the application potential of lignin-based materials.

关键词： Lignin(model compound) CO_(2)absorption Amide group Multi-site Acid-base Hydrogen bonding

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Flow Patterns and Heat Transfer Characteristics of a Polymer Pulsating Heat Pipe Filled with Hydrofluoroether

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Frontiers in Heat and Mass Transfer 2024年第1期22卷 49-63页

作者： Nobuhito Nagasato Zhengyuan Pei Yasushi Koito Department of Mechanical and Mathematical Engineering Graduate School of Science and TechnologyKumamoto UniversityKumamoto860-8555Japan Division of Industrial Fundamentals Faculty of Advanced Science and TechnologyKumamoto UniversityKumamoto860-8555Japan

Visualization experiments were conducted to clarify the operational characteristics of a polymer pulsating heat pipe(PHP).Hydrofluoroether(HFE)-7100 was used as a working fluid,and its filling ratio was 50%of the entire PHP channel.A semi-transparent PHP was fabricated using a transparent polycarbonate sheet and a plastic 3D printer,and the movements of liquid slugs and vapor plugs of the working fluid were captured with a high-speed *** video images were then analyzed to obtain the flow patterns in the *** heat transfer characteristics of the PHPwere discussed based on the flowpatterns and temperature distributions obtainedwith *** starting heating,because of high wettability,large liquid slugs positioned at the evaporator section of the *** starting heating,since the occurrence of boiling divided the large liquid slugs,oscillatory flowof smaller liquid slugs and vapor plugs was found in the *** circulation flow of liquid slugs and vapor plugs was observed when the power input to the PHP was larger than 12.0 *** flow patterns and temperature distributions confirmed that the circulation flow enhanced the heat transfer from the evaporator section to the condenser section of the *** the circulation flow mode,large growth and contraction of vapor plugs were found one after another in all even-numbered PHP ***,the analysis of flow patterns clarified that the phase-change heat transfer rate by large growth and contraction of vapor plugs was 19%of the total heat transfer rate of the *** the generation of large vapor plugs was found in the PHP,most of the heat was transferred by the sensible heat of the working fluid.

关键词： Polymer heat pipe visualization oscillatory flow circulation flow thermal management 3D printer

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A review on different theoretical models of electrocaloric effect for refrigeration

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Frontiers in Energy 2023年第4期17卷 478-503页

作者： Cancan SHAO A.A.AMIROV Houbing HUANG School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China Amirkhanov Institute of Physics Daghestan Scientific Center Russian Academy of SciencesMakhachkala367003Russia

The performance parameters for characterizing the electrocaloric effect are isothermal entropy change and the adiabatic temperature change,*** paper reviews the electrocaloric effect of ferroelectric materials based on different theoretical ***,it provides four different calculation scales(the first-principle-based effective Hamiltonian,the Landau-Devonshire thermodynamic theory,phase-field simulation,and finite element analysis)to explain the basic theory of calculating the electrocaloric ***,it comprehensively reviews the recent progress of these methods in regulating the electrocaloric effect and the generation mechanism of the electrocaloric ***,it summarizes and anticipates the exploration of more novel electrocaloric materials based on the framework constructed by the different computational methods.

关键词： electrocaloric effect effective Hamiltonian phase-field modeling different theoretical models

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Superior QLC Retention (10 years, 85°C) and Record Memory Window (12.2 V) by Gate Stack engineering in Ferroelectric FET: from "MIFIS" to "MIKFIS"

Superior QLC Retention (10 years, 85°C) and Record Memory W...

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2024 IEEE International Electron Devices Meeting, IEDM 2024

作者： Kuk, Song-Hyeon Kim, Bong Ho Park, Youngkeun Ko, Kyul Hwang, Hyeon-Seong Lee, Dahye Cho, Byung Jin Han, Jae-Hoon Kim, Sang-Hyeon School of Electrical Engineering Korea Advanced Institute of Science and Technology Daejeon Korea Republic of Graduate School of Semiconductor Technology Korea Advanced Institute of Science and Technology Daejeon Korea Republic of Korea Institute of Science and Technology Seoul Korea Republic of

ISBN: (纸本)9798350365429

As stacking hundreds of layers, 3D NAND faces new challenges and needs for further scaling. Ferroelectric field-effect-transistor (FEFET) is a potential solution, with advancements in gate stack engineering, specifically the metal-insulator-ferroelectric-insulator-semiconductor (MIFIS) stack, achieving a memory window (MW) over 10 V. However, the gate stack with a feasible MW is still thicker (>18 nm) than that of charge-trap-flash (CTF) NAND, degrading bit density. Additional MW expansion methods using bandgap engineering (BE) with an oxide-nitride-oxide (ONO) layer were also proposed, but further increased the gate stack thickness. Moreover, the previous approaches have critical drawbacks such as monoclinic-(m-) phases in thick FE-HfO2 films, unstable retention, degraded write voltage and speed, and higher equivalent oxide thickness (EOT). To address the issues, we propose a novel gate stack, metal-insulator-high k-ferroelectric-insulator-semiconductor (MIKFIS). The main idea is that the FE-HfO2 thickness can be scaled down by partially replacing it with paraelectric (PE) HfO2, without increasing the gate stack thickness. In addition, fabricated MIKFIS FEFETs show a record MW of 12.2 V with the Si channel, highly reliable 10-year retention with quad-level-cell (QLC) operations at 24ºC and 85ºC for the first time. The origin of the stable retention is revealed by accurately measuring absolute polarization (P) directly from the FEFETs. The superiority of the MIKFIS FEFET indicates that a MIKFIS stack is a strong candidate for the gate stack in 3D FE NAND. © 2024 IEEE.

关键词： Metal insulator boundaries

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Controllable substitutional vanadium doping in wafer-scale molybdenum disulfide films

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Nano Research 2023年第2期16卷 3415-3421页

作者： Jihyung Seo Eunbin Son Jiha Kim Sun-Woo Kim Jeong Min Baik Hyesung Park Department of Materials Science and Engineering Graduate School of Semiconductor Materials and Devices EngineeringGraduate School of Carbon NeutralityLow Dimensional Carbon Materials CenterUlsan National Institute of Science and TechnologyUlsan 44919Republic of Korea School of Advanced Materials Science and Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea SKKU Institute of Energy Science and Technology Sungkyunkwan UniversitySuwon 16419Republic of Korea

Substitutional atomic doping of transition metal dichalcogenides(TMDs)in the chemical vapor deposition(CVD)process is a promising and effective strategy for modifying their physicochemical ***,the conventional CVD method only allows narrow-range modulation of the dopant concentration owing to the low reactivity of the ***,the growth of wafer-scale monolayer TMD films with high dopant concentrations is much more ***,we report a facile doping approach based on liquid precursor-mediated CVD process for achieving high vanadium(V)doping in the MoS_(2)lattice with excellent doping uniformity and *** lateral growth of the host MoS_(2)lattice and the reactivity of the V precursor were simultaneously improved by introducing an alkali metal halide as a reaction *** metal halide promoter enabled the wafer-scale synthesis of V-incorporated MoS_(2)monolayer film with excessively high doping *** excellent wafer-scale uniformity of the highly V-doped MoS_(2)film was confirmed through a series of microscopic,spectroscopic,and electrical analyses.

关键词： doping concentration reaction promoter substitutional doping transition metal dichalcogenides wafer-scale growth

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Atomic regulations of single atom from metal-organic framework derived carbon for advanced water treatment

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Nano Research 2023年第7期16卷 10326-10341页

作者： Xiang Li Bo Wang Key Laboratory of Cluster Science Ministry of Education Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion MaterialsAdvanced Technologies Research Institute(Jinan)Advanced Research Institute of Multidisciplinary ScienceSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyNo.5South StreetZhongguancunHaidian DistrictBeijing 100081China

Single atom(SA)-embedded nitrogen-doped carbon has shown great potential in environmental ***,engineered nanomaterials(ENMs)have attracted great research interests in recent ***-organic framework(MOF)derived SAs show the advantages of tunable topology and averaged separated active *** bridge the gap between homogeneous and heterogeneous *** reaction efficiency can be significantly improved by designing the MOFs derived from carbon and *** this review,the research advanced in MOFs-derived carbon and SAs in advanced oxidation process(AOP)in water were *** strategies to fabricate the SAs derived from MOFs were discussed,including the mixed/single metal strategy,metal-containing linker strategy,pore confinement strategy,thermal diffusion strategy,and pyrolysis MOFs with bulk *** characterization technologies have been introduced,including electron microscopy and spectroscopic *** explain the catalytic mechanism for various applications,the relationship between the performance and the atomic configuration was systematically *** applications of the MOFs derived from carbon and SAs have been summarized.A series of the latest work on effectively removing pollutants by SAs are also *** on the fundamental knowledge and recent practical application of MOFs-derived carbon and SAs,some perspectives on the further directions were *** review offers guidance for applying novel engineered nanomaterials in the water treatment field.

关键词： single-atom catalysts(SACs) engineered nanomaterials(ENMs) metal-organic framework(MOF) MOFs derived carbon water treatment

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A high-flash-point quasi-solid polymer electrolyte for stable nickel-rich lithium metal batteries

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Journal of Energy Chemistry 2024年第12期99卷 149-158页

作者： Yu-Kun Liu Xue-Yan Huang Jun-Dong Zhang Wei-Jin Kong Juan Du Ximin Zhai Xiaofe Bie Huanli Sun Hao Zhang Chong Yan Xuechun Hao Lizhen Fan Ai-Bing Chen Chen-Zi Zhao College of Chemical and Pharmaceutical Engineering Hebei University of Science and TechnologyShijiazhuang 050018HebeiChina Tsinghua Center for Green Chemical Engineering Electrification Beijing Key Laboratory of Green Chemical Reaction Engineering and TechnologyDepartment of Chemical EngineeringTsinghua UniversityBeijing 100084China China FAW Corporation Limited Chuangchun 130013JilinChina Beijing Key Laboratory of Advanced Chemical Energy Storage Technologies and Materials Research Institute of Chemical DefenseBejing 100191China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing 100081China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Shanxi Research Institute for Clean Energy Tsinghua UniversityTaiyuan 030032ShanxiChina Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China

In the exploration of next-generation high-energy–density batteries,lithium metal is regarded as an ideal candidate for anode ***,lithium metal batteries (LMBs) face challenges in practical applications due to the risks associated with organic liquid electrolytes,among which their low flash points are one of the major safety *** adoption of high flash point quasi-solid polymer electrolytes(QSPE) that is compatible with the lithium metal anode and high-voltage cathode is therefore a promising strategy for exploring high-performance and high-safety ***,we employed the in-situ polymerization of poly (epoxidized soya fatty acid Bu esters-isooctyl acrylate-ditrimethylolpropane tetraacrylate)(PEID) to gel the liquid electrolyte that formed a PEID-based QSPE (PEID-QSPE).The flash point of PEID-QSPE rises from 25 to 82℃ after gelation,contributing to enhanced safety of the battery at elevated temperatures,whereas the electrochemical window increases to 4.9 ***,the three-dimensional polymer framework of PEID-QSPE is validated to facilitate the uniform growth of the solid electrolyte interphase on the anode,thereby improving the cycling stability of the *** employing PEID-QSPE,the Li|LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2) cell achieved long-term cycling stability (Coulombic efficiency,99.8%;>200 cycles at 0.1 C) even with a high cathode loading (~5 mg cm^(-2)) and an ultrathin Li(~50μm).This electrolyte is expected to afford inspiring insights for the development of safe and long-term cyclability LMBs.

关键词： Solid-state batteries Lithium metal anodes Quasi-solid polymer electrolytes High flash points Cross-linking polymerization

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Effect of multiphase content on temperature-dependent electrical conductivity in silicone rubber composites

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High Voltage 2023年第2期8卷 283-292页

作者： Ying Lin Yuhao Liu Bin Cao Jianyi Xue Liming Wang Jianing Wang Lijian Ding School of Electrical and Automation Engineering Hefei University of TechnologyHefeiChina Institute of Energy Hefei Comprehensive National Science CenterHefeiChina Laboratory of Advanced Technology of Electrical Engineering and Energy Graduate School at ShenzhenTsinghua UniversityShenzhenGuangdongChina

To investigate how the multiphase structures affect the electrical conductivity in semicrystalline polymer composites,herein,an accurate multiphase content calculation method is proposed and verified,which combines amorphous phase information in broadband dielectric spectroscopy and crystalline phase information in differential scanning *** aluminium hydroxide(ATH)filled silicone rubber as an example,it is found that the rigid amorphous fraction(RAF)corresponding to the chains constrained by crystals(RAF_(cry))is not linearly increased with crystalline fraction(CF).Compared to non-isothermal crystallisation,RAF caused by ATH/silicone rubber interface(RAF_(int))after isothermal crystallisation at 213 K changes little,while mobile amorphous fraction and RAFcry is attenuated and CF is *** on the calculated structures of ATH filled silicone rubber,activation energy of conductivities during cooling is dominated by the thermal transition for conductive ions and shortened distance among the conductive ions through shrunk volumes of the amorphous *** findings deepen the understanding of multiphase content in semi-crystalline polymer composites and its relationship with electrical conductivity,which can be applied in manipulating electrical performance of semi-crystalline polymers by fillers.

关键词： composites rubber electrical

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