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Evaluation of a Numerical Model for Predicting flow and Heat Transfer in a Hexagonal Helical Cruciform Seven-Rods Bundle and Analysis of Rod Bundle Size Independence

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SSRN 2024年

作者： Jiang, Dianqiang Deng, Jian Zhang, Dalin Zhou, Xingguang Xiao, Changzhi Tian, Wenxi Qiu, Suizheng Su, Guanghui H. 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 Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

In this study, the accuracy and applicability of the numerical model are comprehensively evaluated based on the experimental data of a hexagonal helical cruciform (HC) seven-rods bundle. The STAR CCM+ is utilized as a tool to obtain predicted results of flow and heat transfer in different flow regions. The numerical results indicate that it is an improved method to set a negative heat flux on the hexagonal wall in the laminar flow region. The Reynolds stress transport model can accurately predict the experimental results of heat transfer in the transitional flow region, with an average wall temperature deviation of 2.8℃. The SST k-ω model with cubic constitutive option can accurately predict the experimental results of the flow resistance, and a relative error of f is 1.8%. In the turbulent flow region, the SST k-ω model with cubic constitutive option provides an accurate prediction, with an average wall temperature deviation of 3.7℃. The realizable k-Ε two-layer model can accurately predict the flow resistance, and the relative error of f is 0.1%. The preferred numerical model is used to analyze the size independence of the HC rod bundle. This work provides certain guidelines for the accurate simulation in the HC seven-rods bundle. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Numerical Study on Benchmark Analysis of NACIE-UP Facility with Uniform and Non-Uniform power Distribution

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SSRN 2024年

作者： Li, Haoyang Zhang, Dalin Zhou, Lei Deng, Jian Tian, Wenxi Su, Guanghui Qiu, Suizheng 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 Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The NACIE-UP facility is located at the ENEA Brasimone Research Centre and is designed to investigate the thermo-hydraulic properties of LBE within a wire-spaced assembly under uniform and non-uniform power distribution conditions. In this study, the thermo-hydraulic characteristics of FPS are analyzed. ANSYS Fluent solver is applied with the COUPLE algorithm of RANS [[EQUATION]] model. Cheng&Tak correlation and computational conditions are implanted into Fluent in the form of UDFs. The results show that the RMSEs of ADP10SS1 and ADP10SS2 are 2.52 K and 3.69 K, 7.05 K and 8.48 K for ADP06SS1 and ADP06SS2, respectively, which indicate that the adopted models have good prediction ability for the temperature of the experimental conditions. Meanwhile, the heat transfer characteristics are investigated and compared with the correlations of Ushakov, Mikityuk, Kazimi and Carelli. Above all, this study provides quantitative and qualitative analysis for verification and validation of CFD/STH code and stand-alone CFD simulation. © 2024, The Authors. All rights reserved.

关键词： Heat transfer

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On Accelerative Propagation of Premixed Hydrogen/Air Laminar and Turbulent Expanding Flames

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SSRN 2022年

作者： Zhao, Haoran Wang, Jinhua Cai, Xiao Dai, Hongchao Liu, Xiao Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong Universit Xi’an710049 China College of Power and Energy Engineering Harbin Engineering University Harbin150001 China

The accelerative propagation of laminar and turbulent premixed hydrogen/air flames are investigated using a constant volume combustion chamber. Turbulent burning velocity ( S T ) of hydrogen/air mixtures are determined in a wide range of conditions, more importantly the flame propagation dynamics and acceleration exponents are analyzed in detail. Results show that three distinct stages, namely quasi steady, transition acceleration and saturation acceleration stages are distinguished in laminar flame propagation process, and transient acceleration exponent ( a R ) increases in transition acceleration stage while nearly remains as a constant between 1.1~1.25 in saturation acceleration stage. Turbulent flame propagation follows a self-similar acceleration law, and transient acceleration exponent increases continuously as flame propagates outwardly. Furthermore, the empirical correlatio n is obtained to describe the development of turbulent flame acceleration with flame radius. Additionally, global acceleration exponents ( a ) of turbulent flames increase continuously with u ’ / S L and no significant trend variation occurs in different regimes. It appears that the accelerative propagation of turbulent expanding flames is mainly controlled by turbulence stretch, while the effect of flame intrinsic instability is nearly covered in current study. © 2022, The Authors. All rights reserved.

关键词： Acceleration

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Experimental study on the contribution of included/excluded minerals to particulate formation during coal char combustion

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Fuel 2023年第1期346卷

作者： Shang, Yimin Liu, Siqi Niu, Yanqing Zhu, Guangqing Cheng, Zening Hui, Shi'en State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi710049 China China Nuclear Power Technology Research Institute Shenzhen518031 China Zhundong Energy Research Institute Xinjiang Tianchi Energy Co. Ltd. Xinjiang831100 China

The contributions of included and excluded minerals to particulate matter formation are quantified in this work. By devolatilization of three typical Chinese coals, three coal chars with low (LA), moderate (MA), and high ash (HA) content (with both included and excluded minerals) were prepared, from which three float coal chars with low (LA−), moderate (MA−), and high ash (HA−) content (without excluded minerals) were separated by density differentiation method. The coal chars before and after separation were burned in a drop-tube furnace at 1600 K, the results of three float coal chars can directly reveal the contribution of included minerals, and the comparison of two kinds of chars with and without excluded minerals would reveal the excluded mineral contribution to ash distribution. The size distributions of the combustion-generated ash particle were obtained from the combination of ELPI+ and laser particle-size analyzer. The fractions of included/excluded minerals were obtained from SEM images. The results from the combustion of the float chars indicate the physical transformation of included minerals, while the results from original coal chars involve the transformation of both included and excluded minerals. Results indicate that the distribution of ash particles from included minerals for HA− char possesses a single peak, while the ash distributions of MA− and LA− char show a bi-modal shape. The excluded minerals in LA and MA chars mainly contribute to the ash emissions with sizes larger than 80 μm. The contribution from excluded minerals reach 86% to the ash particles of 205 μm for HA char, 54% for MA char and 51% for LA char. The number fractions of included minerals continuously decrease with a transformation into excluded minerals during char dynamic combustion. © 2023 Elsevier Ltd

关键词： Minerals

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Mild Combustion of a Premixed Nh3/Air Jet Flame in Hot Coflow Versus its Ch4/Air Counterpart

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SSRN 2023年

作者： Li, Pengfei Wang, Guochang Liu, Xiangtao Shi, Guodong Cai, Xiao Liu, Zhaohui Mi, Jianchun State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China College of Engineering Peking University Beijing100871 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Dalian Maritime University China

MILD combustion is very suitable for solving the problems of unstable flame and high NOx emission (ENOx ) for ammonia fuel, but the related studies are rare. This work numerically investigates the MILD combustion characteristics of a premixed NH3/air jet flame in hot coflow (JHC) under different jet equivalence ratio (ΦJ), coflow temperature (TC) and oxygen level (XO2,C). For comparison, the similar CH4/air MILD-JHC flames are also calculated. Results show that the NH3 flame generally has lower temperature rise and heat release as well as larger reaction zone than CH4. This may suggest that the former flame can develop to the MILD regime more easily. ENOx is two orders higher from the NH3 than CH4 flame at all TC and XO2,C for ΦJ 1, ENOx of the NH3 flame quickly drops to near zero, but ENH3 and EH2 are very high (~1000 ppm) and the combustion efficiency is low. Moreover, ENOx increases quickly (slowly) with XO2,C (TC) while ENH3 and EH2 are quite low at TC ≥ 1300 K and XO2,C ≥ 1% for the NH3 flame. ENOx mainly comes from NO but N2O is also important at low ΦJ and TC. Therefore, considering all ENOx , ENH3, EH2 and the burning efficiency, the optimal conditions for NH3 MILD combustion are ΦJ =1, TC ≥ 1500 K and XO2,C =1%-3%. In addition, compared to the conventional flame, the NH3 MILD combustion can reduce ENOx by 1-2 orders. © 2023, The Authors. All rights reserved.

关键词： Ammonia

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Experimental Study on Electrocatalytic Reduction of CO2 to Methanol over Cu2O and Cu2O/ZnO films

Experimental Study on Electrocatalytic Reduction of CO2 to M...

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International Conference on power engineering 2021, ICOPE 2021

作者： Zhang, Wenfei Zhou, Qulan Qi, Ji Li, Na State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China China Mobile System Integration Co. Ltd Beijing100052 China

The Cu2O film electrodes were prepared by solution immersion method, the ZnO/Cu2O film electrodes were prepared by electrodeposition method. Then the pure Cu2O film electrodes and ZnO/Cu2O film electrodes were used to reduce CO2 to CH3OH. The crystal structure, morphology, particle size and specific surface area of pure Cu2O films prepared under different immersion time and ZnO/Cu2O films prepared under different deposition time and Zn2+ concentration were analyzed by XRD, SEM, and BET. The electrolytic activity of the pure Cu2O film electrodes and ZnO/Cu2O film electrodes were studied. Under the same reaction conditions, the Cu2O film electrode with 2 h preparation time has the best electrolysis effect in the three groups of pure Cu2O electrode. The increase of reaction temperature can significantly promote the reduction of CO2 to CH3OH on Cu2O film electrodes. the ZnO/Cu2O film electrode with the Zn2+ concentration of 0.05 M and the deposition time of 30 min had the highest total CH3OH yields. This study highlights that the ZnO have a very good promotion of electrolytic CO2 reduction on Cu2O film. © 2021 The Japan Society of Mechanical Engineers.

关键词： Carbon dioxide

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A Novel Water Content Sensor Design and its Application for In-Situ Water Content Measurement Inside the flow Channel of Pemfc

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SSRN 2022年

作者： Zhang, Yan Wang, Weiding Liu, Yukai Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi’an Jiaotong University Xi’an710049 China

In-situ water content detection in proton exchange fuel cell (PEMFC) is of great importance to its water management. In this study, flexible thin film water content microsensor (WCMS) were fabricated and deployed for real-time measurement of water distribution inside the channel of proton exchange membrane fuel cells. The effect of inserting WCMS on the cell performance was confirmed to be negligible. Besides, three WCMS were used to monitor the variation of water distribution in the upstream, midstream and downstream of the flow channel, respectively. The experimental results show that the WCMS can efficiently detect the change of water content inside the fuel cell in real time. The co-occurrence phenomenon of water column clogging in the flow channel and degradation of cell performance were observed. This work provide a novel design of WCMS and its application on the water content distribution inside flow channel of fuel cells. © 2022, The Authors. All rights reserved.

关键词： Proton exchange membrane fuel cells (PEMFC)

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Uncertainty and Sensitivity Analysis of Containment Aerosol Removal Under Severe Accident

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SSRN 2025年

作者： Ou, Pingwen Chen, Yongzheng Chen, Peng Ouyang, Yong Guo, Chao Su, Guanghui China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China State Key Laboratory of Nuclear Power Safety Technology and Equipment China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

This study focuses on the uncertainty and sensitivity analysis of containment aerosol removal under severe accident conditions using the severe accident integral code ASTEC, validated by experiments carried by CNPRI, and the coupled uncertainty and sensitivity tool SUNSET. A "separated" methodology is introduced, which distinguishes between thermal-hydraulic and aerosol boundary conditions to highlight the impact of containment aerosol mechanisms. Eleven uncertainty input parameters related are selected for uncertainty propagation and the Spearman correlation coefficient is utilized to describe sensitivity. The removal factor exhibits significant variation, with peaks due to temporary enhancement of diffusiophoresis deposition caused by corium relocation and subsequent steam generation. Uncertainty in the removal factor is substantial before aerosol release termination and narrows afterward. The gravitational settling and the diffusiophoresis deposition are the most important contributors with approximately 70% and 20% deposited aerosol mass, respectively. The initial mass medium diameter, the gravitational shape factor and the agglomeration shape factor are the most influential input parameters in aerosol removal, including in-containment deposition and environmental release, and they should be considered discreetly with conservatism in source term estimation and radioactive consequence evaluation in nuclear engineering. © 2025, The Authors. All rights reserved.

关键词： Sensitivity analysis

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Research on Bionic Airfoil Design Method Based on Re-Evolution Optimization and Multi Objective Application on Horizontal Axis Wind Turbines

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SSRN 2023年

作者： Huang, ShengXian Yan, Hua Qiu, HuiHe Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and Technology Clear Water Bay Hong Kong

The design of specific airfoil for wind turbine is a crucial factor in the research of wind turbine performance and stability. Based on bionic methods and numerical optimization methods, a brand new airfoil design method is proposed without relying on any traditional airfoil and airfoil design experience. This study proposes a re-evolution method (numerical optimization methods) suitable for designing bionic airfoils based on the previously proposed bionic airfoil (Dol-Rot24°), which was inspired by the Dall's Porpoise. According to this method, a new airfoil is successful designed that gives consideration to both aerodynamic performance and roughness sensitivity. The research content mainly focuses on two aspects: new airfoil design and the new airfoil performance verification. In terms of the new airfoil design, a surrogate model based on radial basic function (RBF) is established for predicting aerodynamic performance and roughness sensitivity of airfoils. This surrogate model can significantly reduce the cost of bionic airfoil optimization calculations, and control the time of 8000 optimization iterations within 1 minute. Based on the actual engineering environment of a horizontal axis wind turbine, the multi-island genetic algorithm is used to adjust the profile of the Dol-Rot 24° airfoil. The optimized airfoil is named Dol-Rot 24° opt. In the performance verification of the Dol Rot 24° opt airfoil, it is found that compared with the Dol Rot 24° airfoil, the lift coefficient of the Dol Rot 24° opt airfoil is increased by 171.06%, and the lift-to-drag ratio is increased by 52.41% at most. Moreover, the roughness sensitivity of the Dol-Rot 24° opt airfoil is also the best among the three airfoils (S809, Dol-Rot 24°, Dol-Rot 24° opt). By modeling the three airfoils according to the NREL Phase VI wind turbine blade parameters and conducting numerical simulations, it is found that the newly optimized wind turbine blades exhibit greatly improved energy efficiency. Th

关键词： Airfoils

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Research on Bionic Airfoil Design Method Based on Re-Evolution Optimization and Multi Objective Application on Horizontal Axis Wind Turbines

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SSRN 2023年

作者： Huang, Shengxian Yan, Hua Qiu, Huihe Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and Technology Clear Water Bay Hong Kong

The design of specific airfoil for wind turbine is a crucial factor in the research of wind turbine performance and stability. Based on biomimetic methods and numerical optimization methods, a brand new airfoil design method is proposed without relying on any traditional airfoil and airfoil design experience. A new airfoil is successful designed that gives consideration to both aerodynamic performance and roughness sensitivity. Based on the actual engineering environment of a horizontal axis wind turbine, the multi-island genetic algorithm is used to adjust the profile of the biomimetic airfoil (Dol-Rot24°). The optimized airfoil is named as Dol-Opt. In the performance verification of the Dol-Opt airfoil, it is found that compared with the Dol-Rot24°, the lift coefficient of the Dol-Opt airfoil is increased by 171.06%, and the lift-to-drag ratio is increased by 52.41% at most. Moreover, the roughness sensitivity of the Dol-Opt is also the optimum among the three airfoils (S809, Dol-Rot 24°, Dol-Opt). By conducting numerical simulations, it is found that the newly optimized wind turbine blades exhibit greatly improved energy efficiency. The purpose of this study is to provide effective references for the design, bionic methods, and practical engineering applications of wind turbine specific airfoils. © 2023, The Authors. All rights reserved.

关键词： Airfoils

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