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Modeling Study on Anisotropic Transport Properties of Pemfc Gdls Facilitated by Xct

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SSRN 2025年

作者： Liu, Hang Li, Yang Huang, Heng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu Hu, Chengzhi Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

The gas diffusion layer (GDL) of proton exchange membrane fuel cells (PEMFCs) is a critical component for the transport of reactants. The efficiency of reactant gas transport remains a major technical challenge in the field today. The anisotropic structure of the GDL gives rise to substantial variations of gas diffusion as well as permeability in different directions. The study employs X-CT technology to obtain the actual GDL’s geometry, aiming to investigate a spatial structure at the microscale and its gas transport characteristics. CFD method is used to simulate and study the gas diffusivity and gas permeability of GDL with four different thicknesses. The numerical simulation results show the diffusivity and permeability in the Through-plane (TP) direction are lower than those in the In-plane (IP) direction. Moreover, the effective diffusion coefficient decreases with increasing thickness, but is also dependent on the solid fibre structure of GDL. Horizontal alignment of the carbon fibers and the disc-shaped adhesive contributes to the anisotropy between the TP and IP directions, resulting in anisotropic gas transport. The purpose of the study is to supply critical references for manufacturing techniques and optimization of gas transport in GDLs. © 2025, The Authors. All rights reserved.

关键词： Gas permeability

Design and Optimal Thermal Efficiency Contrastive Analysis on Closed Brayton Cycle Systems with Different Fluids of Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Liu, Xiuting State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor, the closed Brayton cycle system was selected as the energy conversion system, and the thermodynamic analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed. The results of the thermodynamic analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest and reaching 46.6% with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The results of the exergy analysis show the CO2 cycle has the highest potential to improve thermal efficiency, which has the highest improvement from 43.48% to 49.31% with the recompression process. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD BUNDLE 29

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EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD B...

2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Liu, Weihua Yuan, Hongsheng Wu, Pan Wang, Ting Shan, Jianqiang School of Nuclear Science and Technology Xi'an Jiaotong University No. 28 Xianning West Road Shaanxi Xi'an China China Nuclear Power Technology Research Institute Co. Ltd No.1001 Shangbu Middle Road Futian District Guangdong Shenzhen518026 China The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780791886410

In the current study, a series of reflood tests with uniformly power input have been carried out at the 5×5 rod bundle film boiling test facility of the Nuclear Safety and Operation laboratory(NUSOL) of Xi'an Jiaotong University and the experimental results have been analyzed in detail. The effect of several parameters, including subcooling of coolant (10K to 75K), coolant flow rate (2.5m/s to 10.0m/s) and input wall linear power density (7 W/cm to 13 W/cm) on quench front of reflooding patterns have been studied. It is observed that the quench front during reflood stage of the rod bundle channel is sensitive to above parameters. Increase in input wall linear power density, and decrease in flow rate and subcooling of coolant results in delayed reflooding. The temperature, heat flux and heat transfer coefficient on the rod surface have been got via the self-development Reflooding Experimental Data Analysis (REDA) code. The data is not only useful for the development of theoretical models for film boiling heat transfer, two-phase void fraction, pressure drop, and rod bundle reflooding prediction, but also can be used as a benchmark data base for evaluating the analysis code of Loss of Coolant Accident (LOCA) in reactor and the design of the residual heat removal system. Copyright © 2022 by ASME.

关键词： Coolants

Enhanced Low-Temperature Behavior of Selective Catalytic Reduction of Nox by Co on Fe-Based Catalyst with Looping Oxygen Vacancy

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SSRN 2022年

作者： Pan, Yuqing Li, Na Li, Ke Ran, Shiyuan Wu, Chenyang Zhou, Qulan Liu, Jiyuan Li, Shuzhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Materials Science and Engineering Nanyang Technological University Singapore639798 Singapore Singapore138634 Singapore

The industrial applications of de-NOx require the high activity window of the catalysts to be shifted from high to low temperatures for energy saving. Selective catalytic reduction (SCR) of NOx by CO, as an alternative to NH3-SCR, is a promising de-NOx technology that facilitates the synergistic removal of pollutants. Herein, we report a new Fe2O3/amorphous SiO2 catalyst with high low-temperature activity for CO-SCR. A combination of experiments and density functional theory (DFT) calculations obtains direct evidence that an optimal content of oxygen vacancy enhances the low-temperature NO conversion ratio and N2 selectivity of Fe2O3-based catalyst to over 80% and maintain 100% CO conversion by promoting NN coupling via ONNO/N2O and NCO/NNCO2 intermediates. Compared with conventional defect engineering, such as doping other metals or artificially generating oxygen defects, the α-Fe2O3 (110) facet automatically enables an oxygen vacancy generation-filling cycle in the CO-SCR reaction, following Mars-van Krevelen (MvK) mechanism. This work advances a fundamental understanding of CO-SCR reaction mechanism over Fe2O3-based catalysts and provides insights for future studies to improve heterogeneous metal oxide catalysts. © 2022, The Authors. All rights reserved.

关键词： Oxygen vacancies

Design and Optimal Thermal Efficiency Analysis on Closed Brayton Cycle System of Fluoride-Salt-Cooled High-Temperature Advanced Reactor (Fustar)

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, G.H. Zhao, Quanbin Liu, Xiuting State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR): the high temperature, inherent safety, compact structure, and modularization, the closed Brayton cycle system was selected as the energy conversion system, and the enthalpy analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed, at the highest thermal efficiencies. The results of enthalpy analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The exergy analysis shows the CO2 cycle has the highest potential to improve thermal efficiency. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system. © 2022, The Authors. All rights reserved.

关键词： Enthalpy

Boosting photocatalytic hydrogen production by creating isotype heterojunctions and single-atom active sites in highly-crystallized carbon nitride

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Science Bulletin 2022年第5期67卷 520-528,M0004页

作者： Shaohua Shen Jie Chen Yiqing Wang Chung-Li Dong Fanqi Meng Qinghua Zhang Yiliang Huangfu Zhi Lin Yu-Cheng Huang Yanrui Li Mingtao Li Lin Gu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanChina Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity,but is yet to be ***,we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride(CCN)to triazine-based poly(triazine imide)(PTI),rendering the creation of singleatom cobalt coordinated isotype CCN/PTI ***-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88%at 425 nm for photocatalytic hydrogen production with a rate achieving3538μmol h^(-1)g^(-1)(λ>420 nm),which is 4.8 times that of CCN and 27.6 times that of *** high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration,and the single-atom Co sites for accelerating surface oxidation reaction.

关键词： Photocatalytic hydrogen production Single-atom cobalt Crystalline carbon nitride Poly(triazine imide) Isotype heterojunctions

Development and technical progress in large-scale circulating fluidized bed boiler in China

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Frontiers in Energy 2020年第4期14卷 699-714页

作者： Zhong HUANG Lei DENG Defu CHE State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Circulating fluidized bed(CFB)boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime,high sulfur coal,anthracite,petroleum coke,oil shale and other *** a country with the largest amount of CFB boilers and the largest installed capacity in the world,China has 440100-600 MWe CFB boilers with a total capacity of 82.29 GWe,including 227 units of 135 MWe,95 units of300 MWe,and 24 supercritical *** statistics of typical 100-300 MWe CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year,among which the 135 MWe was 0.26 times per year and 300 MWe was 0.46 times per ycai*.The auxiliary power ratio of some 300 MWe CFB boilers based on flow-pattern reconstruction can be reduced to about 4%,which is closed to the same level of pulverized coal(PC)*** paper summarizes the development process and application status of China's large-scale CFB boilers,analyzes the characteristics and technical performance of the iconic units,and introduces solutions to the problems such as water wall wear and bottom ash cooling.

关键词： CFB boiler installed capacity reliability economics ultra-low emission China

Atomic Nickel on Graphitic Carbon Nitride as a Visible Light-Driven Hydrogen Production Photocatalyst Studied by X-ray Spectromicroscopy

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ACS Sustainable Chemistry and Engineering 2023年第14期11卷 5390-5399页

作者： Huang, Yu-Cheng Li, Yanrui Arul, K. Thanigai Ohigashi, Takuji Nga, Ta Thi Thuy Lu, Ying-Rui Chen, Chi-Liang Chen, Jeng-Lung Shen, Shaohua Pong, Way-Faung Dong, Chung-Li Chou, Wu-Ching Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Research Center for X-ray Science & Department of Physics Tamkang University New Taipei City25137 Taiwan International Research Center for Renewable Energy State Key laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukabu305-0801 Japan UVSOR Synchrotron Facility Institute for Molecular Science Okazaki444-8585 Japan National Synchrotron Radiation Research Center Hsinchu30010 Taiwan

The photocatalytic production of solar hydrogen through water splitting by graphitic carbon nitride (g-C3N4) has gained substantial interest due to its advantageous characteristics, such as eco-friendliness, wealth on the earth, favorable bandgap, and easy preparation. Nevertheless, the performance for photocatalytic overall water splitting has been significantly restricted owing to the rapid recombination of charge carriers and slow catalytic kinetics. This investigation demonstrates the utilization of a single-atom Ni-terminating agent to coordinate with the heptazine moieties of g-C3N4, resulting in the formation of a new electronic orbital. g-C3N4 with single-atom Ni-termination can achieve highly efficient photocatalytic overall water splitting into H2 and H2O2 upon visible light irradiation, without requiring the use of any additional cocatalysts. The underlying cause of the enhanced photocatalytic performance of single-atom Ni-incorporated g-C3N4 in hydrogen evolution reaction is identified using synchrotron X-ray spectroscopy and microscopy. The X-ray spectro-microscopic results discover that the new hybrid orbital that is critical for optimizing photocatalysis is associated with carbon defects. The atomic and electronic structures and the band gap of g-C3N4 are adjusted by the new hybrid orbital. Moreover, it synergistically enhances visible light absorption, thereby promoting the separation and transfer of photogenerated charge carriers. The single-atom Ni and the adjacent C atom are recognized as the active sites for water oxidation and reduction, respectively, supporting the efficient photocatalytic splitting of water via a two-electron transfer pathway. This study demonstrated a promising material design for promoting photocatalytic activity in solar energy conversion applications. © 2023 American Chemical Society

关键词： Electronic structure

Experimental Study on Leakage of High-Energy Fluids Through Narrow Elliptical Slits

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SSRN 2024年

作者： Bi, Qincheng Zhang, Tao Zhao, Jinle Wang, Teng Yang, Zhendong Gui, Miao State Key Lab Multiphase Flow Power Engn Xi'an Jiaotong University Shaanxi Xian710049 China Department of Power Engineering North China Electric Power University Baoding071003 China State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of Technology Shaanxi Xian710048 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xian710049 China

This study is focused on the leakage flow rate of high-energy fluid passing through narrow elliptical slits with large aspect ratios, which is an issue in the application of the leak-before-break concept. Experiments were conducted using a high-temperature and high-pressure experimental platform at Xi’an Jiaotong University, where the temperature reached up to 320 ℃ and the pressure reached up to 10 MPa. These temperatures and pressures encompass a wide range of operating conditions (single-phase cold water, liquid-vapor (two-phase) mixture, and superheated steam). A series of narrow elliptical slits with different aspect ratios (528-2083) and hydraulic diameters (226-412 um) were used in the experiments. The experimental results were compared with previous model. Based on the experimental data and the the effects of the aspect ratio, the mathematical model was corrected, and the results obtained from the modified model conform well with the experimental results. © 2024, The Authors. All rights reserved.

关键词： Aspect ratio