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Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels

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Chinese Journal of Aeronautics 2023年第1期36卷 201-215页

作者： Xiaoyong LIU Zhuqiang YANG Ruipu MIAO Feng LIU Shujun ZHAO Qincheng BI Beijing Power Machinery Research Institute Beijing 100074China Liaoning Key Laboratory of Complex Energy Conversion and Utilization School of Energy and Power EngineeringDalian University of TechnologyDalian 116024China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type Ⅰ and Type Ⅱ excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature,system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling.

关键词： flow distribution Ledinegg instability Onset of flow excursion Parallel channels Regenerative cooling Scramjet Supercritical flow

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Defect-engineered WO_(x)/ZnIn_(2)S_(4)Z-scheme heterojunction boosting photocatalytic H_(2)production via photothermal coupling

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Journal of Energy Chemistry 2025年第4期103卷 9-18页

作者： Biao Wang Chunyang Zhang Shidong Zhao Shujian Wang Feng Liu Kejian Lu Yitao Si Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189JiangsuChina Suzhou Academy of Xi’an Jiaotong University Suzhou 215123JiangsuChina

Recent interest in photocatalytic water splitting has intensified the demand in the development of photocatalysts capable of harnessing the full *** study introduces a novel WO_(x)/ZnIn_(2)S_(4)Zscheme heterojunction,prepared by depositing ZnIn_(2)S_(4)(ZIS)nanosheets onto WO_(x)nanorods,enabling efficient photothermal-coupled photocatalytic H_(2)*** success relies on the engineered oxygen vacancies within WO_(x)nanorods,which not only confer excellent photothermal properties lowering the reaction barrier but also create defect levels in WO_(x)facilitating Z-scheme electron transfer from these levels to the valence band of ***,the optimized WO_(x)/ZIS heterojunction exhibits a remarkable H_(2)evolution rate of 33.91 mmol h^(-1)g^(-1)with an apparent quantum efficiency of 23.6%at 400 *** study provides a new strategy for developing efficient Z-scheme heterojunctions with broadspectrum solar hydrogen production capabilities.

关键词： Defect-engineered Z-scheme heterojunction Photocatalytic H2evolution Photothermal coupling

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Numerical simulation and structural optimization of spiral finned tube thermal energy storage

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International Journal of Advanced Nuclear Reactor Design and Technology 2023年第3期5卷 123-136页

作者： Ma, Yunfei Meng, Yu Li, Jingyu Chen, Weixiong Yang, Xiaohu Li, Shaodan Chong, Daotong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Wuhan Second Ship Design and Research Institute Wuhan430205 China

Thermal energy storage (TES) has emerged as a promising solution to enhance nuclear safety by passively removing decay heat during reactor shutdown and accidents, thus preventing overheating of the reactor core and protecting the integrity of containment barriers. The research of TES with different structures has broad application prospects and practical significance. In this study, the melting process of phase change material (PCM) in various TES structures was simulated by the numerical simulation method in two and three dimensions. The mechanism of gravity-driven natural convection enhancing heat transfer was revealed. The effects of different TES structures, fin pitch, fin height, and fin thickness on heat transfer performance were studied. The results showed that many vortices formed by liquid PCM are the main reason for enhancing the natural convection. Adding fins could greatly accelerate the heat storage process. The melting time of PCM in annular and spiral finned tube TES was 47.3% and 61.3% less than that in smooth tube TES, respectively. In the present study, the heat transfer effect was enhanced as the spiral fin pitch became small, the fin height increased and the fin thickness increased. Two opposite effects of fin structure on the natural convection were revealed: (1) positive effect provided by heat transfer enhancement and (2) negative effect produced by blockage. © 2023 Xi'an Jiaotong University

关键词： Phase change materials

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A direct polymeric carbon nitride/tungsten oxide Z-scheme heterostructure for efficient photocatalytic hydrogen generation via reforming of plastics into value-added chemicals

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Rare Metals 2024年第8期43卷 3771-3783页

作者： Rui-Zhe Wang Zhi Lin Yi-Qing Wang Kai-Ni Zhang Ge-Hong Zhang Jie Zhang Samuel S.Mao Shao-Hua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China School of Civil and Architecture Engineering Xi'an Technological UniversityXi'an 710021China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA94720USA

To promote charge transfer and separation for efficient photocatalysis,a direct Z-scheme heterostructure was constructed by coupling polymeric carbon nitride(PCN) and WO_(3).Interestingly,the obtained PCN/WO_(3)Z-scheme heterostructure could photocataly tic ally produce hydrogen and value-added chemicals(e.g.,formate and acetate) by reforming of plastic polylactic acid(PLA) in alkaline aqueous *** optimizing WO_(3) contents and reaction conditions,the obtained PCN/WO_(3)heterostructure exhibits much increased photocatalytic activity for PLA photoreforming under visible light,with hydrogen evolution rate reaching 402.90 μmol·g~(-1)·h~(-1),which is 3.5 times that of *** is revealed that the Z-scheme charge transfer between PCN and WO_(3) mainly contributes to the promoted charge separation and thus the improved photocatalytic ***,with h+and·OH experimentally evidenced as the predominant active species,a possible reaction pathway for the reforming of PLA into value-added chemicals(e.g.,formate and acetate)over PCN/WO_(3) Z-scheme heterostructure is cleared by monitoring the reaction intermediates and *** work paves a carbon neutrality and scalable route toward the synergistical production of hydrogen and value-added chemicals by utilizing and recycling plastic waste.

关键词： Carbon nitride Z-scheme heterojunction Plastic waste conversion Photocatalytic H_(2)production Value-added chemicals

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Photocatalytic water splitting on BiVO_(4):Balanced charge-carrier consumption and selective redox reaction

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Nano Research 2023年第4期16卷 4568-4573页

作者： Xiangjiu Guan Li Tian Yazhou Zhang Jinwen Shi Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Suzhou Academy of Xi’an Jiaotong University Suzhou 215123China State Key Laboratory for Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China

Surficial redox reactions play an essential role in photocatalytic water splitting,and are closely related to the surface properties of a specific *** this work,using monoclinic BiVO_(4)decahedral single crystals as a model photocatalyst,we report on the interrelationship between the photocatalytic activity and the surficial reaction sites for charge-carrier *** controlled hydrothermal synthesis,the ratio of{010}to{110}facets on BiVO_(4),which respectively serve as reductive and oxidative sites,is carefully *** results show that superior photocatalytic water oxidation could be obtained on BiVO_(4)decahedrons with a medium ratio of reductive/oxidative sites and that efficient overall water splitting could be achieved via further modification of appropriate cocatalysts in Z-scheme *** excellent photocatalytic performance is attributed to the accelerated selective redox reactions by realizing balanced charge-carrier consumption,which provides insightful guidance for prospering photocatalytic reactions in energy conversion.

关键词： BiVO_(4) photocatalytic water splitting reactive site

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EFFECT OF BLENDING STRAW POWDER INTO COAL GANGUE ON LOADING-UP CHARACTERISTICS OF THE CIRCULATING FLUIDIZED BED GENERATOR UNIT

EFFECT OF BLENDING STRAW POWDER INTO COAL GANGUE ON LOADING-...

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ASME 2024 Power Conference, POWER 2024

作者： Zhao, Chenyu Wang, Chaoyang Liu, Ming Liu, Jiping Yan, Junjie MOE Key Laboratory of Thermal Fluid Science Engineering Xi'an Jiaotong University Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791888186

To increase the contribution to the regional environment, the feasibility of blending agricultural residues was explored by a circulating fluidized bed (CFB) generator unit using coal gangue as the single fuel. In this study, straw powder was chosen to blend into the coal gangue, and the whole thermal system was built as a dynamic model based on self-programming and GSE software. Blending affects the load-increasing process from 75 % to 100 % rated power (Pe) with a load variation rate of 1 % Pe/min. With the blended fuel, the deviation of the output power was almost unchanged, and the maximum deviation of the live steam pressure was reduced by 0.04 MPa. With the blending ratios of 10 % and 20 %, the energy efficiencies of the whole unit were improved by 0.48% and 0.81%, respectively, the accumulative deviations of live steam temperature were reduced by 10.4% and 16.5%, respectively, the accumulative deviations of reheat steam temperature were reduced by 13.3% and 18.2% respectively, and the maximum deviations of bed temperature were increased to 8.9 ℃ and 9.5 ℃ respectively. The increased fluctuations in bed temperature are still far from the safe boundary, so the CFB generator unit can safely load up with the blending ratios of 10 % and 20 %. Copyright © 2024 by ASME.

关键词： Coal

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Progress and challenge of functional single-atom catalysts for the catalytic oxidation of volatile organic compounds

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Chinese Chemical Letters 2024年第9期35卷 83-91页

作者： Zeyu Jiang Yadi Wang Changwei Chen Chi He Department of Environmental Science and Engineering Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China National Engineering Laboratory for VOCs Pollution Control Material&Technology University of Chinese Academy of SciencesBeijing 101408China

The catalytic oxidation of volatile organic compounds(VOCs)is of considerable significance for the sustainable development of the chemical industry;thus,considerable efforts have been devoted to the exploration of efficient catalysts for use in this *** this regard,the development and utilization of single-atom catalysts(SACs)in VOCs decomposition is a rapidly expanding research *** can be employed as potential catalysts for oxidizing VOC molecules due to their optimal utilization efficiency,unique atomic bonding structures,and unsaturated *** has been achieved,while the challenges surrounding precise regulation of the microstructures of SACs for improving their low-temperature efficiency,stability,and product selectivity under practical conditions are ***,elucidating structure-performance relationships and establishing intrinsic modulating mechanisms are urgently required for guiding researchers on how to synthesize effective and stable functional SACs ***,recent advances in the design and synthesis of functional SACs for application in the catalytic oxidation of VOCs are *** experimental and theoretical studies revealing higher efficiency,stability,and selectivity of as-prepared functional SACs are being ***,the future perspectives in terms of promising catalysts with multi-sized composite active sites and the illustration of intrinsic mechanism are *** rapid intelligent screening of applicable SACs and their industrial applications are also discussed.

关键词： Single-atom catalysts VOCs catalytic oxidation Hydrocarbon activation Oxygen species transformation Surface chemistry Intrinsic mechanism

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Impacts of Startup,Shutdown and Load Variation on Transient Temperature and Thermal Stress Fields within Blades of Gas Turbines

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Journal of Thermal Science 2022年第3期31卷 727-740页

作者： CAI Liuxi HOU Yanfang LI Fang LI Yun WANG Shunsen MAO Jingru School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

Based on the actual operation parameters and temperature-dependent material properties of a gas turbine unit,composite cooling blade model and corresponding reliable boundary conditions were *** thermal-fluid-solid coupling simulations were then comprehensively conducted to analyze the transient flow and the temperature field of the blade under startup,shutdown,and variable loads *** with the obtained transient temperature data,the non-linear finite element method was exploited to examine the effect of these transient operations on the turbine blade thermal stress *** show that the temperature and pressure on the blade surface increase with the load level and vice *** the startup process progresses,the film cooling effectiveness and the heat convection of airflows inside the blade continuously grow;high-temperature areas on the pressure surface and along the trailing edge of the blade tip gradually *** high-temperature zones with the maximum of 1280 K are generated at the air inlet and outlet of the blade platform and the leading edge of the blade *** high thermal stresses detected on the higher temperature side of the temperature gradient are commonly generated in places with large temperature gradients and significant geometry *** the startup/shutdown process,the rate of increase/decrease of the thermal stress is positively correlated with the load variation rate.A slight variation rate of the load(1.52%/min)can lead to an apparent alteration(41%)to the thermal *** operations under action of the variable load,although thermal stress is less sensitive to the load variation,the rising or falling rate of the exerted load still needs to be carefully controlled due to the highly leveled thermal stresses.

关键词： composite cooling blade thermal-fluid-solid coupling method transient temperature field load variation thermal stress

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N and O vacancies regulation over semiconductor heterojunction to synergistically boost photocatalytic hydrogen peroxide production

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Journal of Materials Science & Technology 2024年第29期196卷 237-247页

作者： Chaoqian Ai Bing Luo Chunyang Zhang Yadi Wang Baoyuan Wang Lijing Ma Dengwei Jing International Research Center for Renewable Energy&State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Chemical Engineering School of Water and Environment&Key Laboratory of Subsurface Hydrology and Ecology in Arid AreasMinistry of Education Chang’an UniversityXi’an 710054China

Defect engineering represents a potent strategy for the modification of electronic properties by introducing atomic vacancies in ***,the synergistic enhancement attributable to different types of atomic vacancies within a heterojunction,as well as their underlying mechanisms,remains sparsely ***,the flexible g-C_(3)N_(4)materials with varying nitrogen vacancies were prepared via a facile calcination method under different atmospheric conditions and then composited with CeO_(2)nanocubes to construct Z-scheme *** was observed that CeO_(2)has abundant O vacancies,and the g-C_(3)N_(4)form tertiary nitrogen defects at the center of the heptazine units under an NH3 atmosphere *** resulting enhancement in the interfacial built-in electric field,coupled with the synergistic effect of O and N vacancies within the Z-scheme heterojunction,has been demonstrated to significantly enhance charge transfer *** results in an optimized photoactivity with a H_(2)O_(2)generation rate of 2.01 mmol g^(-1)h^(-1).This work opens an avenue for constructing and optimizing the heterogeneous photocatalysts by defect engineering technology,and provides deep insight to understand the nature of vacancy engineering in designing effective catalysts for solar energy conversion.

关键词： Photocatalysis H_(2)O_(2) production Z-scheme Defect engineering Synergy effect

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NUMERICAL SIMULATION OF SINGLE/TWO-PHASE flow IN A STRATIFIED POROUS BED 31

NUMERICAL SIMULATION OF SINGLE/TWO-PHASE FLOW IN A STRATIFIE...

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2024 31st International Conference on Nuclear engineering, ICONE 2024

作者： Bouloudenine, Aimad Li, Liangxing Xiang, Zutao Shi, Shang Bakar, Muhammad Abu Xi’an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xianning West Road 28 Xi’an City710049 China

ISBN: (纸本)9780791888292

This study investigates the coolability of debris beds formed from Fuel-Coolant Interactions (FCI) within nuclear reactors, a critical safety concern when cooling systems fail, leading to significant core melting in light-water reactors. The research focuses on understanding the flow dynamics within two-layer stratified porous beds, which develop from the mixture of corium and coolant, particularly around the interface between layers. Using ANSYS Fluent software, numerical simulations were conducted to estimate velocity profiles and pressure drops across a stratified porous structure. The Euler-Euler two-fluid model was employed alongside the k-ω-based Shear Stress Transport (SST) turbulence model to separately model turbulence for each phase. The results reveal that lateral flow dynamics are significant as fluids traverse through the porous media, affecting pressure drops across layers with varying permeabilities. Specifically, the pressure drops across the lower-permeability layer decrease while that across the higher-permeability layer increases, highlighting the influence of lateral flows between layers of different particle sizes due to variations in porosity. This lateral flow is most likely formed during the initial stages of fluid movement through the bed. The study underscores the importance of understanding these flow characteristics for both single/two-phase flow to enhance the safety and design of nuclear reactors by improving debris bed coolability predictions. Copyright © 2024 by ASME.

关键词： Computational fluid dynamics

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