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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Li, Wei Wu, Xiaoli Tian, Wenxi Qiu, Suizheng Su, Guanghui Lu, Qi 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 State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an710049 China Science Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China

Helical cruciform fuels are novel in nuclear reactors, potential to increase reactor’s power density. However, the geometry is complicated so influence of it on the fuel performance is not identified yet. In this paper, impact of power density, cross-section parameters, and twist pitch on thermal and mechanical characteristics of fuel used in Fluoride-Salt-cooled high-Temperature Advanced Reactor is discussed based on fluid-thermal-mechanical coupling. For thermal features, twist pitch is key while others have few effects. Increase in twist pitch leads to temperature uniformity and rise owing to weaker mixing effects. Fuel center temperature at middle plane of 300mm-pitch rod is 829.58℃, 54.66℃ higher than that of 100mm-pitch rod. Difference of maximum and minimum temperature at 45° cross section of 500mm-pitch rod is 153.62℃, while the figure is only 74.00℃ of 300mm-pitch rod. Besides, axial temperature of cladding outer surface increases wavelike due to complex geometry. For mechanical features, not geometry sizes but temperature affects stress distribution. Maximum Von-Mises stress appears at the elbow, where maximum temperature exists, 116.8MPa under normal conditions, lower than tensile strength of the material. After identifying the influence of these factors, five dimensionless parameters are proposed to evaluate and rate fuel performance based on Technique for Order Preference by Similarity to an Ideal Solution. As a result, an optimization comes up, scoring 0.310, twice more than the original design, owing to the thermal uniformity and mechanical safety. This study provides a reference for identifying and evaluating the performance of helical structure. © 2024, The Authors. All rights reserved.

关键词： Geometry

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A New Structure Tube for Supercritical Co 2 Turbulent flow with High Non-Uniform Heat Flux

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SSRN 2023年

作者： Wang, Yanjuan Gao, Shuo Shi, Weijie Liu, Qibin Xu, Jinliang The Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power University Beijing102206 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100190 China

Supercritical carbon dioxide (sCO2) has been a promising alternative working medium in coal-fired power plants, high-temperature solar power systems, and fuel cells. In these cases, sCO2 is in a round tube under high temperature and pressure with high non-uniform heat flux (NUH). In this study, a novel structure tube is proposed to match high NUH with thermal resistance by changing tube eccentricity. A three-dimensional (3D) multiphysical coupling model was constructed. The novel structure can reduce Tmax and T effectively for the half-cycle uniform heat flux (HUH) and NUH cases. The maximum thermal stress decreased by 23 and 29% and Tmax decreased by 29.6 K and 24.8 K for HUH and NUH cases when Ec increased from 0 to 0.4. A comparison was made between the proposed structure, thin-walled tube, and traditional tube. Results showed that the performance of the proposed tube is the best. Tmax decreases by approximately 55 K compared with the traditional and thin-walled tubes. σeq,max of the eccentric tube is the smallest. Furthermore, the structure will facilitate the safety and economics of the tube. Consequently, a novel insight is presented for the design and optimization of sCO2 tube under high NUH. © 2023, The Authors. All rights reserved.

关键词： Heat transfer

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Preparation and Photocatalytic Activities of Magnetic TiO2/Fe3O4 Composite Nanoparticles

Preparation and Photocatalytic Activities of Magnetic TiO2/F...

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UK-China Symposium of New Energy Materials and Nanotechnology(2012年中英纳米技术和新能源材料研讨会)

作者： SU Jie CHENG Wen MA Xia LIU Rui LI Huiqiang YAN Yanli Xi''an University of Technology Xi''an 710048China Xi''an 710049 China Key Laboratory of Northwest Water Resources Environment and Ecology Ministry of Education State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiao tong University Xi''an University of Technology Xi''an 710048China Key Laboratory of Northwest Water ResourcesEnvironment and Ecology Ministry of Education

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Boiling of Water Droplet in Glass-Oil-Water multiphase System

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SSRN 2022年

作者： He, Xiaotian Cheng, Yiwei Xu, Jinliang Yu, Xiongjiang Xie, Jian Ma, Xiaojing Ren, Yong Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Beijing102206 China Key Laboratory of Power Station Energy Transfer Conversion and System of Ministry of Education North China Electric Power University Beijing102206 China Research Group for Fluids and Thermal Engineering University of Nottingham Ningbo China Ningbo315100 China

Boiling of a volatile droplet in a non-volatile liquid becomes complex due to various interface interactions in a solid-liquid-liquid system. Available studies reported explosive boiling and attributed the phenomenon to heterogeneous nucleation due to solid-liquid contact. Here, we investigate boiling of ~2 mm diameter water droplet in a silicon oil pool with glass container. Two transition temperatures are observed, with one as the transition from evaporation to boiling (122.5 o C), and the other as the transition from bubble growth in oil side to that in both oil and water side (160.0 o C). Correspondingly, four boiling modes of evaporation (E), boiling in water (BIW: bubble nucleation at glass-water interface and growth inside drop), boiling in oil (BIO: nucleation at oil-water interface and growth in oil), and boiling in oil and water (BIOW: nucleation at oil-water interface and growth in oil and water), are identified. For the first time, boiling bifurcation is found for drop boiling in a three-phase system. For oil temperature T b in the range of (122.5~160.0) o C, boiling mode switches in between BIW and BIO. On the contrary, for T b beyond of 160.0 o C, either BIW or BIOW occurs. This bifurcation is explained by the fact that a droplet prefers to choose smaller activation energy between that for bubble nucleation at solid-water interface and that for bubble nucleation at oil-water interface. Interfacial instabilities are analyzed to explain why BIOW boils more violently than BIW. Our work presents a comprehensive understanding of droplet boiling in the three-phase system. © 2022, The Authors. All rights reserved.

关键词： Bifurcation (mathematics)

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Fault Diagnosis of Rolling Bearing Using Cnn and Pca Fractal Based on Feature Extraction

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SSRN 2023年

作者： Xiao, Junqing Li, Chun Yue, Minnan Xu, Zifei Liu, Qingsong School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Department of Maritime and Mechanical Engineering Liverpool John Moores University Byrom Street LiverpoolL3 3AF United Kingdom

A novel adaptive decomposition algorithm based on CEMMDAN and fractal dimension is proposed in this study in order to overcome the limitations like redundancy and mode confusion that exist in traditional EMD based algorithms. An intelligent fault diagnosis model is developed based on CNN and the proposed CEMMDAN for improving the performance of states recognition of rolling bearings. all sub-signals generated by CEEMDAN are selected and reconstructed by the PCA and fractal dimension. In the part if feature extraction and pattern recognition, the proposed ICEEMDAN uses CNN to extract advanced features from the reconstructed signal for developing the intelligent diagnosis model. The performance of the proposed method is examined by rolling bearing experiments. The superiority and reliability of the proposed ICEEMDAN method are compared with some CNN-based diagnosis method. Due to the investigation and examination, the proposed ICEEMDAN method has strong robustness even dealing with the noisy testing background. © 2023, The Authors. All rights reserved.

关键词： Empirical mode decomposition

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Investigation on heat transfer characteristics of fully developed flow in bilaterally heated narrow annuli

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Hedongli Gongcheng/Nuclear power engineering 2006年第SUPPL. 1期27卷 57-60页

作者： Zeng, He-Yi Qiu, Sui-Zheng Jia, Dou-Nan School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Numerical research was carried out on the convection heat transfer characteristics in bilaterally heated annular channel with narrow gap under the conditions of fully developed flow, where the inner and outer walls are heated by uniform but unequal heat fluxes. Calculation results show that the ratio of the inner wall heat flux to the outer wall heat flux has great effects on the heat transfer characteristics in bilaterally heated narrow annuli. With the increase of the inner wall heated flux, the heat transfer coefficient at the outer wall of the inner tube will decrease, while the heat transfer coefficient at the inner wall of outer tube will increase. These numerical results are in good agreement with some experimental results in open literatures. Numerical results also show that the decrease of the annuli gap will yield heat transfer deterioration during flowing in narrow annular channels.

关键词： Heat transfer

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Influence of dolomite additive on the ash fusion and potassium fixation characteristics of rice straw

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Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology 2020年第7期48卷 795-803页

作者： Yu, Zhi-Hao Jin, Jing Zhang, Rui-Pu Zhao, Bing Zhu, Yi-Zhou Wang, Guang-Xu School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

The influence of dolomite as an additive on the slagging and potassium fixation characteristics of rice straw upon burning was investigated in a tube furnace;the slagging mechanism as well as the interaction between the rice straw ash and dolomite were explored by using the inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The results show that the slagging characteristics of rice straw are significantly influenced by adding 5% dolomite. Dolomite can greatly improve the potassium fixation ability, especially at 900-1000℃;moreover, the Mg and Ca elements rich in dolomite can react with SiO2 in the rice straw ash, forming high-melting silicate minerals including diopside, monticellite and merwinite. © 2020, Science Press. All right reserved.

关键词： Dolomite

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Development, Validation and Application of Sub-Channel Thermal-Hydraulic Analysis Code for Liquid Metal Cooled Reactor

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SSRN 2024年

作者： Wang, Jinshun Chen, Ronghua Liang, Yu Gui, Minyang Zhu, Xinyang Tian, Wenxi Qiu, Suizheng Su, Guanghui School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering 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 College of Nuclear Science and Technology Harbin Engineering University Harbin150001 China

The liquid metal reactor, specifically the lead-based fast reactor and the sodium-cooled fast reactor, are generally recognized as the most significant representatives of the Gen IV reactors due to their sustainability, economy, security and reliability. In order to conduct thermal-hydraulic safety analysis for liquid metal cooled fast reactors, adaptive improvements are made to the model and solution algorithms based on the sub-channel analysis method, and a Sub-channel Analysis Code Of Safety for Liquid Metal cooled Reactor (SACOS-LMR) is developed. The validation of SACOS-LMR is conducted using classic experimental data of liquid metal. The results show that the dimensionless temperature deviations of ORNL 19-pin test and Toshiba 37-pin test are within 10%, and the relative temperature deviations of KIT-KALLA 19-pin test are within 25%. These findings confirm the accuracy and reliability of SACOS-LMR in predicting the temperature distribution of liquid metal reactors. Ultimately, calculations conducted on the ALFRED lead-cooled fast reactor demonstrated the practical utility of the code and have certain guiding significance for its subsequent design and development. © 2024, The Authors. All rights reserved.

关键词： Liquid metals

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Customizable Ligand Exchange for Tailored Surface Property of Noble Metal Nanocrystals

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研究（英文） 2020年第3期 192-203页

作者： Qikui Fan Hao Yang Juan Ge Shumeng Zhang Zhaojun Liu Bo Lei Tao Cheng Youyong Li Yadong Yin Chuanbo Gao Frontier Institute of Science and Technology State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University Xi'an Shaanxi 710054 China Institute of Functional Nano & Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices Joint International Research Laboratory of Carbon-Based Functional Materials and Devices Soochow UniversitySuzhou Jiangsu 215123 China Department of Chemistry University of California Riverside California 92521 USA

It is highly desirable,while still challenging,to obtain noble metal nanocrystals with custom capping ligands,because their colloidal synthesis relies on specific capping ligands for the shape control while conventional ligand exchange processes suffer from 'the strong replaces the weak' limitation,which greatly hinders their ***,we report a general and effective ligand exchange approach that can replace the native capping ligands of noble metal nanocrystals with virtually any type of ligands,producing flexibly tailored surface *** key is to use diethylamine with conveniently switchable binding affinity to the metal surface as an intermediate *** a strong ligand,it in its original form can effectively remove the native ligands;while protonated,it loses its binding affinity and facilitates the adsorption of new ligands,especially weak ones,onto the metal *** this means,the irreversible order in the conventional ligand exchange processes could be *** efficacy of the strategy is demonstrated by mutual exchange of the capping ligands among cetyltrimethylammonium,citrate,polyvinylpyrrolidone,and *** novel strategy significantly expands our ability to manipulate the surface property of noble metal nanocrystals and extends their applicability to a wide range of fields,particularly biomedical applications.

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Comparison of Lifetime Performance of Pemfc Stacks with Two Cooling Strategies Under Different Humidity

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SSRN 2024年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Lv, Jizu Hu, Chengzhi Li, Yang 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 School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

While reducing the size and Pt loading can achieve a lower proton exchange membrane fuel cell (PEMFC) stack cost, it is also very important to focus on the performance changes of the PEMFC stack during the long-term operation. A 3D PtCo catalysts long-term performance model is established in this study, and PEMFC stacks with one cooling unit per cell (1-cell stack) and three cells (3-cell stack) are employed as the computational domains, respectively. The effective area of each cell is 50 cm2, and the changes in current density as well as effective catalytic area of PEMFC stacks with two cooling strategies before and after long-term operation under different humidity conditions are investigated at low Pt loadings. The results show that there are large differences in the output voltage and current density distributions between the three cells due to the poor membrane hydration affected by the non-uniform temperature distribution, although the 3-cell stack can significantly reduce the size. Localized catalyst degradation in both 3-cell and 1-cell stacks is closely related to the geometry of the cathodic flow field, and non-uniform catalyst degradation is found to increase the activation and mass transfer losses and change the distribution of current density within the membrane. In addition, the 3-cell stack is found to perform even better in terms of durability, especially under high humidity conditions, which provides a potential solution to improve the durability of PEMFC stacks operating in harsh conditions. © 2024, The Authors. All rights reserved.

关键词： Durability

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