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Uncertainty analysis of molten corium In-Vessel Retention under External Reactor Vessel Cooling

International Journal of Advanced Nuclear Reactor Design and Technology 2023年第4期5卷 159-167页

作者： Wu, Shihao Wang, Dong Zhang, Yapei Zhou, Yukun Tian, Wenxi Qiu, Suizheng Su, G.H. School of Nuclear Science and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

External Reactor Vessel Cooling (ERVC) is a key measure to realize molten corium In-Vessel Retention (IVR). The uncertainty of severe accident in core leads to the uncertainty of molten pool parameters in lower head, which may threat the reliability of successful implementation of IVR. In this study, an uncertainty analysis is employed to ensure the reliability of ERVC technology to IVR with the final two-layer molten pool configuration of AP1000.600 simulations are performed to determine the effect of five key parameters. As long as parameters are within high probability density range, lower head can remain intact, and safety margin is greater than 15 %. For influence level and correlation of parameters, the order on metal layer is: Decay heat > Fe mass > UO2 mass > Zr oxidation fraction > Emissivity of metal layer. The results can provide guidance for subsequent research direction and optimal design of mitigation measures. © 2024 Xi'an Jiaotong University

关键词： Uncertainty analysis

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The evaporation of nanoscale sodium liquid film on the non-ideal nanostructure surface: A molecular dynamics study

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International Journal of Advanced Nuclear Reactor Design and Technology 2023年第1期5卷 1-8页

作者： Wang, Zetao Ye, Tianzhou Guo, Kailun Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Lab of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

The nanoscale liquid sodium film inside the microporous wick structure is of great importance to understanding the evaporation mechanism of the sodium heat pipe. The novel optimized wick structure is made of several layers of special screen. The surface of each screen exhibits a nanostructure type. Some non-ideal nanostructures may result from experimental faults or limits. And they will have an effect on the evaporation of film. In the present study, molecular dynamics is adopted to investigate this effect. The simulation system consists of the liquid sodium film and the solid surface. The flat surface is set as the reference. Based on the three non-ideal shapes of deposition, the sinusoidal nanostructures, conical nanostructures, and spherical nanostructures are built. The results indicate that the evaporation is suppressed by the above nanostructure surfaces. The weakening effect is through three forms: the potential gradient of the liquid film is intensified and the evaporation difficulty is increased;the heat transfer in the solid-liquid contact region is impeded;the collision heat transfer inside the liquid film is affected due to the delay of the aggregation variation between liquid atoms. © 2023 Xi'an Jiaotong University

关键词： Heat pipes

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Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and elevated pressure

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Frontiers in Energy 2022年第2期16卷 263-276页

作者： Geyuan YIN Chaojun WANG Meng ZHOU Yajie ZHOU Erjiang HU Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Thermal EngineeringTsinghua UniversityBeijing 100084China

The laminar flame speeds of ammonia mixed with syngas at a high pressure, temperature, and different syngas ratios were measured. The data obtained were fitted at different pressures, temperatures, syngas ratios, and equivalence ratios. Four kinetic models (the Glarborg model, Shrestha model, Mei model, and Han model) were compared and validated with experimental data. Pathway, sensitivity and radical pool analysis are conducted to find out the deep kinetic insight on ammonia oxidation and NO formation. The pathway analysis shows that H abstraction reactions and NHi combination reactions play important roles in ammonia oxidation. NO formation is closely related to H, OH, the O radical produced, and formation reactions. NO is mainly formed from reaction, HNO+ H= NO+ H2. Furthermore, both ammonia oxidation and NO formation are sensitive to small radical reactions and ammonia related reactions.

关键词： ammonia mixed with syngas laminar flame speed kinetic model sensitivity analysis pathway analysis

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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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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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