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Numerical investigation of natural convection characteristics of a heat pipe-cooled passive residual heat removal system for molten salt reactors

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Nuclear Science and Techniques 2020年第7期31卷 25-33页

作者： Cheng-Long Wang Hao Qin Da-Lin Zhang Wen-Xi Tian Guang-Hui Su Sui-Zheng Qiu Department of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The limited availability of studies on the natural convection heat transfer characteristics of fluoride salt has hindered progress in the design of passive residual heat removal systems(PRHRS)for molten salt *** paper presents results from a numerical investigation of natural convection heat transfer characteristics of fluoride salt and heat pipes in the drain tank of a *** results are compared with experimental data,demonstrating the accuracy of the calculation *** distribution of fluoride salt and heat transfer characteristics are obtained and *** radial temperature of liquid fluoride salt in the drain tank shows a uniform distribution,while temperatures increase with increase in axial height from the bottom to the top of the drain *** addition,natural convection intensity increases with increase in height of the heat pipes in the *** between heat pipes has no obvious effect on the natural convection heat transfer *** study will contribute to the design of passive heat removal systems for advanced nuclear reactors.

关键词： passive characteristics pipes

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Kinetics of hydrogen abstraction and addition reactions of 3-hexene by H radical

Kinetics of hydrogen abstraction and addition reactions of 3...

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11th Asia-Pacific Conference on Combustion, ASPACC 2017

作者： Yang, Feiyu Sun, Wuchuan Pan, Youshun Deng, Fuquan Jiang, Xue Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xianning West Road Xi’anShaanxi710049 China

Rate coefficients of H-atom abstraction and addition reactions of 3-hexene by the hydroxyl radical (H) were determined using canonical variational transition-state theory, with potential energy surface evaluated at the CCSD/CBS//BHandHLYP/6311G (d, p) level and quantum mechanical effect corrected by the multi-dimensional small-curvature tunneling method. Results reveal that accounting for approximate 70% of the overall H-atom abstractions occur in the allylic site via both direct and indirect channels. The indirect channel containing two Van der Waals pre-reactive complexes exhibits two times higher rate coefficient relative to the direct one. The H-addition reaction also contains two Van der Waals complexes, and its submerged barrier results in a negative temperature coefficient behavior at low temperatures. In contrast, the H-addition pathway dominates only at the temperatures below 590 K whereas the H-atom abstraction reactions dominate overwhelmingly at the temperature over 590 K. All of the rate coefficients calculated with an uncertainty of a factor of 5 were estimated. Analyses on the potential energy surface and minimum reaction path were also performed in this study. © 2018 Combustion Institute. All Rights Reserved.

关键词： Addition reactions

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Simulation study on mineral transformation behaviors and ash fusion characteristics during high-alkali coal combustion under deep peaking conditions

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Fuel 2025年 399卷

作者： Liu, Jiamiao Ma, Guowei Du, Yongbo Wang, Chang'an Zhao, Yonggang Wu, Wanzhu Shi, Longping Zhao, Lin Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China National Energy Group Science and Technology Research Institute Co. Ltd. Nanjing210046 China Company Xi'an710076 China Huayuan Power Plant National Energy Group Hami Coal Power Co. Ltd. Hami839000 China

The safe and efficient combustion of high-alkali coal under deep peaking conditions remains a critical research focus. Boiler operating parameters under such conditions frequently fluctuate, markedly though incompletely understood in their influence on fouling and slagging, necessitating further investigation. Here, mineral transformation and ash fusion characteristics during high-alkali coal combustion in the main combustion zone were simulated through thermodynamic equilibrium calculations, addressing its fouling issues under deep peaking conditions. Variable loads were decomposed into distinct factors for analysis due to challenges of direct simulation. Additionally, the plasma ashing method was employed to prepare ash samples. High-alkali coals with distinct properties exhibit significant variations in mineral distribution, elemental evolution, ash fusion temperature, and viscosity. Abundant fayalite (Fe2SiO4) was observed in Hongshaquan (HSQ) coal, forming stable mineral phases with other components. In Shaerhu (SEH) coal, sodium primarily exists in the gaseous phase at high temperatures, significantly contributing to fouling. Meanwhile, Jiangjunmiao (JJM) and Wucaiwan (WCW) coals demonstrate limited mineral phases but higher ash fusion temperatures, with over 30 % of iron in the gaseous phase. The mineral transformation and ash fusion behaviors in various local combustion atmospheres follow consistent trends. The formations of gaseous sodium hydroxide (NaOH(g)) and sodium oxide in the slag phase (Na2O(slag)) are promoted with weakening reducing atmospheres, while total gaseous sodium content decreases. The slag phases of calcium, magnesium, and iron increase, accompanied by a decline in ash viscosity. However, unburned carbon inversely influences mineral transformation and ash fusion characteristics compared to excess air coefficients. This research provides theoretical support for overcoming the key technical challenges associated with high-alkali coal combus

关键词： Iron analysis

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Development and application of a UTSG thermal-hydraulic analysis code

Development and application of a UTSG thermal-hydraulic anal...

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International Congress on Advances in Nuclear power Plants, ICAPP 2014

作者： Cong, Tenglong Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781632668264

Structural integrity of steam generator should be maintained during operation, since it performs as the pressure boundary of primary side coolant. Localized thermal-hydraulic parameters of secondary side are essential for the analysis of tube wastage, fatigue and failure. In this paper, a three-dimensional thermohydraulics analysis code, named STAF, is developed based on FLUENT. With STAF code, three-dimensional thermohydraulics of secondary side of AP1000 steam generator are generated. This code is developed based on the porous media theory. In this code, the drift flux two-phase model coupled with a simplified flow boiling model is utilized to present two-phase flow among the U-tube bundle. Downcomer, tube bundle, support plates and primary separators in steam generator are considered in STAF code. The calculated results are compared with a general steam generator thermohydraulic analysis code ATHOS, which is developed by the Westinghouse. The comparison indicates that STAF code performs well in evaluating thermal-hydraulic parameters in steam generator. The results show that the flow field varies significantly at different position in AP1000 steam generator. flow vapor quality at the inlet of primary separators varies significantly, which is a severe challenge to the capacity design of separators.

关键词： Steam generators

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Analysis of CHF in saturated forced convective boiling on a heated surface with impinging jets using artificial neural network and genetic algorithm

Analysis of CHF in saturated forced convective boiling on a ...

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作者： Cong, Tenglong Chen, Ronghua Su, Guanghui Qiu, Suizheng Tian, Wenxi School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China

In this paper, a three-layer Back Propagation (BP) algorithm artificial neural network (ANN) for predicting critical heat flux (CHF) in saturated forced convective boiling on a heated surface with impinging jets was trained successfully with a root mean square (RMS) error of 17.39%. The input parameters of the ANN are liquid-to-vapor density ratio, ρl/ ρv, the ratio of characteristic dimension of the heated surface to the diameter of the impinging jet, L/d, reciprocal of the Weber number, 2σ/ρlu2(L - d), and the number of impinging jets, Nj. The output is dimensionless heat flux, qco/ ρvHfgu. Based on the trained ANN, the influence of principal parameters on CHF has been analyzed as follows. CHF increases with an increase in jet velocity and decreases with an increase in L/d and N j. CHF increases with an increase in pressure at first and then decreases. Besides, a new correlation was generalized using genetic algorithm (GA) as a comparison with ANN to confirm the advantage of ANN. © 2011 Published by Elsevier B.V.

关键词： Heat flux

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Coupled neutronics/thermal-hydraulics and safety characteristics of liquid-fueled Molten Salt Reactors

Coupled neutronics/thermal-hydraulics and safety characteris...

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作者： Qiu, S. Zhang, D. Liu, L. Liu, M. Xu, R. Gong, C. Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

Molten salt reactor (MSR) as one candidate of the Generation IV advanced nuclear power systems is attracted more attention in China due to its top ranked fuel cycle and thorium utilization. The MSRs are characterized by using liquid-fuel, which offers complicated coupling problem of neutronics and thermal hydraulics. In this paper, the fundamental model and numerical method are established to calculate and analyze the safety characteristics for liquid-fuel MSRs. The theories and methodologies are applied to the MOSART concept. The liquid-fuel flow effects on neutronics, reactivity coefficients and three operation parameters' influences at steady state are obtained, which provide the basic information for safety analysis. The unprotected loss of flow transient is calculated, the results of which shows the inherent safety characteristics of MOSART due to its strong negative reactivity feedbacks. © Carl Hanser Verlag, München.

关键词： Molten salt reactor

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Activating ZnO nanorod photoanodes in visible light by Cu ion implantation

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Nano Research 2014年第3期7卷 353-364页

作者： Meng Wang Feng Ren Guangxu Cai Yichao Liu Shaohua Shen Liejin Guo International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi 710049 China School of Physics and Technology Center for Ion Beam Application Wuhan University Wuhan 430072 China

Utilization of visible light is of crucial importance for exploiting efficient semiconductor catalysts for solar water splitting. In this study, an advanced ion implantation method was utilized to dope Cu ions into ZnO nanorod arrays for photoelectrochemical water splitting in visible light. X-ray diffraction （XRD） and X-ray photo-electron spectroscopy （XPS） results revealed that Cu^＋ together with a small amount of Cu^2＋ were highly dispersed within the ZnO nanorod arrays. The Cu ion doped ZnO nanorod arrays displayed extended optical absorption and enhanced photoelectrochemical performance under visible light illumination （A 〉 420 nm）. A considerable photocurrent density of 18 μA/cm^2 at 0.8 V （vs. a saturated calomel electrode） was achieved, which was about 11 times higher than that of undoped ZnO nanorod arrays. This study proposes that ion implantation could be an effective approach for developing novel visible-light-driven photocatalytic materials for water splitting.

关键词： ion implantation Cu ion doping ZnO nanorods photoanode water splitting

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Construction of Pd-M （M = Ni, Ag, Cu） alloy surfaces for catalytic applications

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Nano Research 2018年第2期11卷 780-790页

作者： Xiang Li Xixi Wang Maochang Liu Hongyang Liu Qiang Chen Yadong Yin Mingshang Jin Frontier Institute of Science and Technology (FIST) School of Chemical Engineering and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing China Department of Chemistry University of California Riverside USA

The fabrication of ultrathin alloy shells as heterogeneous catalysts to increase the utilization efficiency and enhance the catalytic activity of metal atoms has been recognized as an effective method for the construction of efficient metal nanocatalysts, particularly noble-metal nanocatalysts. In this study, we demonstrate the successful formation of Pd-M （M = Ni, Ag, Cu） alloy shells with a tunable thickness on preformed nanoscale Pd seeds. The success of this synthesis mainly relies on the combination of the slow reduction of ＂M＂ ions and the subsequent diffusion of M ad-atoms into the surface lattice of Pd seeds. The composition of the Pd-M alloy shell is easily tuned by changing the type and amount of the added precursor, and the shell thickness is manipulated according to the reaction time. More significantl the surface structure of these alloy shells is maintained after the reaction, implying that any desired surface structure of Pd-M alloy shells can be prepared by using the appropriate starting materials. Further catalytic evaluation of the hydrogenation of chloronitrobenzenes shows that these alloy surfaces exhibit significantly improved selectivity compared to the Pd seeds. The Pd-Ni alloy surfaces exhibit much better catalytic selectivity （as high as 〉 99%） than Pd catalysts.

关键词： Pd allo3 catalyst shape control hydrogenation

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Electronic Structures and Optical Absorption Properties of Ni-doped Anatase TiO2for Photocatalysis from First-Principles Calculation 18

Electronic Structures and Optical Absorption Properties of N...

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18th World Hydrogen Energy Conference, WHEC 2010

作者： Liu, Maochang Zhou, Zhaohui Li, Mingtao Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University 28 Xianning Street Shaanxi Xi'an710049 China

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Operando modeling and measurements:powerful tools for revealing the mechanism of alkali carbonate-based sorbents for CO_(2)capture in real conditions

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Frontiers in Energy 2023年第3期17卷 380-389页

作者： Tianyi CAI Mengshi WANG Xiaoping CHEN Ye WU Jiliang MA Wu ZHOU School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Energy Thermal Conversion and Control of the Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Key Laboratory of Thermal Control of Electronic Equipment and Advanced Combustion Laboratory of the Ministry of Industry and Information Technology School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

Alkalicarbonate-based sorbents(ACSs),including Na_(2)CO_(3)-and K2CO_(3)-based sorbents,are promising for CO_(2)***,the complex sorbent components and operation conditions lead to the versatile kinetics of CO_(2)sorption on these *** paper proposed that operando modeling and measurements are powerful tools to understand the mechanism of sorbents in real operating conditions,facilitating the sorbent development,reactor design,and operation parameter *** reviewed the theoretical simulation achievements during the development of *** elucidated the findings obtained by utilizing density functional theory(DFT)calculations,ab initio molecular dynamics(AIMD)simulations,and classical molecular dynamics(CMD)simulations as *** hygroscopicity of sorbent and the humidity of gas flow are crucial to shifting the carbonation reaction from the gas-solid mode to the gas-liquid mode,boosting the ***,it briefly introduced a machine learning(ML)approach as a promising method to aid sorbent ***,it demonstrated a conceptual compact operando measurement system in order to understand the behavior of ACSs in the real operation *** proposed measurement system includes a micro fluidizedbed(MFB)reactor for kinetic analysis,a multi-camera sub-system for 3D particle movement tracking,and a combined Raman and IR sub-system for solid/gas components and temperature *** is believed that this system is useful to evaluate the real-time sorbent performance,validating the theoretical prediction and promoting the industrial scale-up of ACSs for CO_(2)capture.

关键词： CO_(2)capture carbonation theoretical modeling operando techniques reaction visualization

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