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arXiv 2023年

作者： Xu, Fan Su, Jinghong Lan, Bin Zhao, Peng He, Yurong Sun, Chao Wang, Junwu School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences P. O. Box 353 Beijing100190 China School of Chemical Engineering University of Chinese Academy of Sciences Beijing100049 China Innovation Academy for Green Manufacture Chinese Academy of Sciences Beijing100190 China Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing100084 China Department of Engineering Mechanics School of Aerospace Engineering Tsinghua University Beijing100084 China

Direct numerical simulations are performed to explore the effects of the rotating direction of the vertically asymmetric rough wall on the transport properties of Taylor-Couette (TC) flow, up to a Taylor number of Ta = 2.39×107. It is shown that, compared to the smooth wall, the rough wall with vertical asymmetric strips can enhance the dimensionless torque Nuω. More importantly, at high Ta, clockwise rotation of the inner rough wall (where the fluid is sheared by the steeper slope side of the strips) results in a significantly greater torque enhancement compared to counter-clockwise rotation (where the fluid is sheared by the smaller slope side of the strips), due to the larger convective contribution to the angular velocity flux. However, the rotating direction has a negligible effect on the torque at low Ta. The larger torque enhancement caused by the clockwise rotation of the vertically asymmetric rough wall at high Ta is then explained by the stronger coupling between the rough wall and the bulk, attributed to the larger biased azimuthal velocity toward the rough wall at the mid-gap of the TC system, the increased turbulence intensity manifested by larger Reynolds stress and a thinner boundary layer, and the more significant contribution of the pressure force on the surface of the rough wall to the torque. Copyright © 2023, The Authors. All rights reserved.

关键词： Direct numerical simulation

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Thermal management matters in photovoltaic–electrocatalysis for solar hydrogen production

EcoEnergy

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EcoEnergy 2024年

作者： Jie Chen Xin Chen Jie Sun Jingkuo Qu Xiangjiu Guan Shaohua Shen School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Photovoltaic–electrolysis (PV-EC) system currently exhibits the highest solar to hydrogen conversion efficiency (STH) among various technical routes. This perspective shifts the focus from the materials exploration in photovoltaics and electrolysis to the critical aspect of thermal management in a PV-EC system. Initially, the theoretical basis that elucidates the relationships between temperature and the performance of both photovoltaics and electrolyzers are presented. Following that, the impact of thermal management on the performance of PV-EC for solar hydrogen production is experimentally demonstrated by designing variables-controlling experiments. It is observed that while utilizing identical PV and EC cells under varying thermal conditions, the highest STH can reach 22.20%, whilst the lowest is only 15.61%. This variation underscores the significance of thermal management in optimizing PV-EC systems. Finally, increased efforts to enhancing heat transfer and optimizing heat distribution are proposed, thus facilitating the design of more efficient PV-EC systems with minimized thermal energy losses.

关键词： device design photovoltaic-electrolysis solar to hydrogen thermal management water electrolyzer

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Degradation of polyethylene terephthalate (PET) and polypropylene (PP) plastics in seawater

DeCarbon

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DeCarbon 2023年 1卷

作者： Meixin Guan Hui Jin Wenwen Wei Mi Yan State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF) Xi'an Jiaotong University 28 Xianning West Road Xi'an 710049 Shaanxi China State Key Laboratory of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310027 Zhejiang China

The world's marine litter consists mainly of plastic, and 99% of it does not float on the surface of the sea but on the seabed. The plastic carbon footprint necessarily includes the extraction or manufacture of raw materials, the conversion process, the distribution of products, the consumption of specific types of products and the disposal of the final product, as all these stages release carbon into the atmosphere. This work, inspired by marine microplastics and investigates how plastic waste is degraded and transformed in high-pressure, low-temperature seawater, this paper investigates the corrosion of polyethylene terephthalate (PET) and polypropylene (PP) plastics in seawater at high-pressure, using artificial seawater temperatures to simulate ocean temperatures of approximately 4 °C and time settings of 1 day–7 days. The results show that increasing the time enhances the degradation of the plastics and that changing the pressure has little effect on the degradation effect. Understanding its degradation in seawater can help us to better treat plastic waste and thus reduce the carbon footprint of the disposal process.

关键词： PET PP High-pressure seawater Degradation

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Numerical simulation on filling process of drag reduction agent in natural gas pipeline

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Journal of Physics: Conference Series 2021年第1期1985卷

作者： Xiaoyun Yin Jiaqiang Jing Peiyu Jing Jie Sun Ying Yuan School of Oil & Natural Gas Engineering Southwest Petroleum University Chengdu China Oil & Gas Fire Protection Key Laboratory of Sichuan Province Chengdu China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

In this paper, a numerical simulation is established to model the filling process of atomized natural gas drag reduction agent (DRA) at the pipeline inlet section. The computations are on the basis of the Euler-Lagrange method with the standard k-ε turbulence model. The effects of atomizing parameters on the droplets Sauter Mean Diameter (SMD) and the adsorption performance on the wall of pipe are investigated using the validated model. The results show that nozzle diameter and nozzle angle have little effect on the SMD of DRA droplets, whereas the size of the droplets SMD reduces with the increase of atomizing pressure, and the influence of atomizing flow rate is just the opposite.

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Encapsulation of Co/Co3o4 Hetero-Nanoparticles within the Inner Tips of N-Doped Carbon Nanotubes: engineering Mott-Schottky Nanoreactors for Efficient Bifunctional Oxygen Electrocalysis Toward Flexible Zinc-Air Batteries

SSRN

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SSRN 2022年

作者： Zhang, Binbin Lu, Tingyu Ren, Yiping Huang, Longzhen Pang, Huan Zhao, Qun Tian, Shu Yang, Jun Xu, Lin Tang, Yawen Tian, Xinlong School of Chemistry and Materials Science Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials Nanjing Normal University Nanjing210023 China School of Chemistry and Chemical Engineering Yangzhou University Yangzhou225009 China College of Chemistry and Chemical Engineering Nantong University Nantong226019 China Nanjing IPE Institute of Green Manufacturing Industry Nanjing211100 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine Chemistry School of Chemical Engineering and Technology Hainan University Haikou570228 China

We demonstrate a typical Mott-Schottky electrocatalyst by ingeniously encasing Co/Co3O4 hetero-nanoparticles within the inner tips of N-doped carbon nanotubes (abbreviated as Co/Co3O4@N-CNTs hereafter) through a facile and scalable hydrogel-bridged pyrolysis strategy. Experimental and theoretical findings collectively manifest that the spontaneous charge redistribution at the Co/Co3O4 heterointerfaces is essential to promote the charge transfer capability, lower down the reaction barriers for oxygen electrocatalysis, and ultimately boost the intrinsic activities. Accordingly, the well-designed Co/Co3O4@N-CNTs exhibit admirable ORR and OER activities and long-term robustness in KOH medium, exceeding the commercial Pt/C and RuO2 benchmarks, respectively. Furthermore, the Co/Co3O4@N-CNTs-assembled flexible all-solid-state zinc-air battery displays a high power density, remarkable rate capability, excellent rechargeablity and outstanding mechanical flexibility even under severe deformations, predicting the great potentials in diverse next-generation wearable electronic devices. The rationale of the construction of Mott-Schottky heterojunctions may provide an innovative and instructive avenue to design diversified energy nanomaterials. © 2022, The Authors. All rights reserved.

关键词： Doping (additives)

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Phosphorus Flame Retardant Modified Aramid Nanofiber Separator for Advanced Safety Lithium-Sulfur Batteries

SSRN

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SSRN 2024年

作者： Liu, Jianwei Zhu, Lei Wang, Jianan Chai, Qinqin Sun, Shiyi Chen, Xin Wang, Xue Zhang, Yating Yan, Wei College of Chemistry and Chemical Engineering Xi’an University of Science and Technology Shaanxi Xi’an710054 China Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao tong University Shaanxi Xi’an710049 China Xianggui Manganese Industry Co. Ltd. Shaanxi Province Ziyang County725300 China School of Physics and Electrical Engineering Weinan Normal University Shaanxi Weinan714099 China Xi'an Hantang Analysis & Test Co. Ltd Xi’an710201 China

Safety concerns have perennially impeded the large-scale implementation of high-energy-density storage systems. Nevertheless, because the intrinsic drawbacks of the commercial polyolefin separator are poor thermal stability and low flammability with a large thermal contribution, the development of an advanced separator that solves the above questions is imminent. In this work, gradient flame-retardant aramid nanofiber separators (T-PMIA) were synthesized by a single-step electrospinning method. The T-PMIA separator demonstrates excellent Li-ion diffusion and proficiently suppresses the "shuttle effect" through its plentiful multilevel beaded structure and robust anchoring of soluble polysulfides (Li2Sx), achieved by optimizing the functional groups P and -P-O. Moreover, the enhanced separator exhibits a rapid self-extinguishing feature (self-extinguishing time: 0.20 s) and impressive mechanical properties (tensile strength of up to 12.58 MPa and puncture force of 0.94 N). Accordingly, the T-PMIA separator still showed a stable cycling performance (maintain 901.7 mAg-1 after 100 cycles) even at high temperature (80 ℃). This simple separator strategy offers a highly competitive option for the large-scale production of high-safety lithium-sulfur (Li-S) batteries. This uncomplicated separator strategy presents a compelling solution for the large-scale production of high-safety lithium-sulfur (Li-S) batteries © 2024, The Authors. All rights reserved.

关键词： Separators

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Correction to: Modification of a first‑generation solid oxide fuel cell cathode with Co3O4 nanocubes having selectively exposed crystal planes

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Materials for Renewable and Sustainable Energy 2022年第3期11卷 299-299页

作者： Xu, Xi Wang, Chao Fronzi, Marco Liu, Xuehua Bi, Lei Institute of Materials for Energy and Environment College of Materials Science and Engineering Qingdao University Qingdao China State Key Laboratory of Multiphase Flow in Power Engineering International Research Centre for Renewable Energy Xi’an Jiaotong University Xi’an China

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Beam dynamics induced by the quantum metric of exceptional rings

arXiv

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arXiv 2024年

作者： Zhang, Zhaoyang Septembre, Ismaël Liu, Zhenzhi Kokhanchik, Pavel Liang, Shun Liu, Fu Li, Changbiao Wang, Hongxing Liu, Maochang Zhang, Yanpeng Xiao, Min Malpuech, Guillaume Solnyshkov, Dmitry Key Laboratory for Physical Electronics and Devices The Ministry of Education Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information Xi’an Jiaotong University Xi’an710049 China Institut Pascal PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP Clermont-FerrandF-63000 France Naturwissenschaftlich-Technische Fakultät Universität Siegen Walter-Flex-Straße 3 Siegen57068 Germany International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Physics University of Arkansas FayettevilleAR72701 United States Paris75231 France

Topological physics has broadened its scope from the study of topological insulating phases to include nodal phases containing band structure singularities. The geometry of the corresponding quantum states is described by the quantum metric which provides a theoretical framework for explaining phenomena that conventional approaches fail to address. The field has become even broader by encompassing non-Hermitian singularities: in addition to Dirac, Weyl nodes, or nodal lines, it is now common to encounter exceptional points, exceptional or Weyl rings, and even Weyl spheres. They give access to fascinating effects that cannot be reached within the Hermitian picture. However, the quantum geometry of non-Hermitian singularities is not a straightforward extension of the Hermitian one, remaining far less understood. Here, we study experimentally and theoretically the dynamics of wave packets at exceptional rings stemming from Dirac points in a photonic honeycomb lattice. First, we demonstrate a transition between conical diffraction and non-Hermitian broadening in real space. Next, we predict and demonstrate a new non-Hermitian effect in the reciprocal space, induced by the non-orthogonality of the eigenstates. We call it transverse non-Hermitian drift, and its description requires biorthogonal quantum metric. The non-Hermitian drift can be used for applications in beam steering. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

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A study of a computational BVP for heat transfer and friction drag in magnetohydrodynamics viscous flow of a nanofluid subject to the curved surface

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Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical engineering 2021年

作者： Khan, M Riaz Saleel, C Ahamed Saeed, Tareq Allehiany, F.M. El-Refaey, Adel M Jing, Dengwei Mahmoud, Emad E LSEC and ICMSEC Academy of Mathematics and Systems Science Chinese Academy of Sciences China School of Mathematical Science University of Chinese Academy of Sciences China Department of Mechanical Engineering College of Engineering King Khalid University Saudi Arabia -Research Group Department of Mathematics Faculty of Science King Abdulaziz University Saudi Arabia Department of Mathematical Sciences College of Applied Sciences Umm Al-Qura University Saudi Arabia Department of Basic and Applied Science College of Engineering and Technology Arab Academy for Science Technology Maritime Transport Smart Village Campus Egypt State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China Department of Mathematics and Statistics College of Science Taif University Taif Saudi Arabia

The ongoing work investigates the features of Joule heating and convective condition over a magnetohydrodynamic stagnation point flow of (Formula presented.) nanofluid moving across a curved surface. Moreover, mass suction is supposed through the stretching/shrinking surface. The initially developed model of partial differential equations is transformed into the ordinary ones assisted by suitable similarity variables. Subsequently, the ultimate nonlinear model of ordinary differential equations is solved with the help of a built-in function bvp4c package in MATLAB. Several graphical results are plotted to see the influence of various dimensionless parameters over the velocity, temperature, heat transfer, and friction drag. We found that there exists an escalation in temperature with increasing values of curvature, Eckert number, Hartmann number, and Biot number;however, the velocity profile declines with large curvature, ratio parameter, and high concentration of nanoparticles. It is also important to note that the friction drag rises with the mass suction, and reduces with vast curvature, whereas the rate of heat transfer improves with suction and Biot number but lowers with Eckert number and Hartmann number. © IMechE 2021.

关键词： Magnetohydrodynamics

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Vapor condensation with low air mass fraction inside water seal branch tube under free convection

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Nuclear engineering and Design 2021年 379卷

作者： Bing Tan Xi Wang Y.W. Wu W.X. Tian S.Z. Qiu G.H. Su School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi an 710049 China School of Electric Power South China University of Technology Guangzhou 510640 China

The pressure vessel has used a newly designed water seal structure, and the sealed water is from condensation at low hydrogen concentration. To get the condensation capacity of the water seal branch tube under the pressure vessel normal operation, the experimental loop named WASETEL was constructed, which is aimed at studying the heat transfer during the process of air-steam mixture condensation inside the inclined branch tube at the condition of low air mass fraction. The inner tube is diameter 0.134 m with length 0.68 m which is connected with diameter 1.4 m, high 2.5 m pressure vessel. A canon camera was set to record the images and videos of the condensate height through glass tube in communicating vessel liquidometer. The experiment was conducted under the pressure ranged from 0.2 to 0.6 MPa, air mass concentration ranged from 0.49 to 6.42% and wall subcooling ranged from 11 to 40 K. The test showed HTC (heat transfer coefficient) would sharply deteriorate with the small air fraction, compared with pure steam condensation, about 0.49% mass fraction of the air will reduce heat transfer coefficient by 70–80%. When air concentration is relatively small, those widely used relations can not predict the condensation well, therefore, a new heat transfer empirical correlation with air mass fraction, pressure and subcooling is proposed, covered all the experimental data within the error band ±13%.

关键词： Natural condensation New empirical correlation Water seal

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