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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Zhang, Shuangbao Li, Liangxing Xie, Wei Wang, Kailin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi’an city710049 China

The high temperature gas-cooled reactor (HTR) is well known for its prominent inherent safety, high efficiency and low carbon environmental protection, which has been identified as one of the candidates for the Generation IV nuclear energy system technology. Accurate and reliable thermal hydraulic analysis is of great significance to the system design and safe operation of HTR. Based on the coolant flow and heat transfer process in the core of HTR, this study establishes a three-dimensional model by using CFD (Computational Fluid Dynamics) software firstly, and the flow and heat transfer process of helium coolant is simulate in the core. The temperature distribution of HTR is calculated at steady state, and the calculation results were compared with the related published results for validation and verification. After that, the models are employed to study the thermal hydraulic characteristics under the loss of coolant accident of HTR. The results show that as the coolant passes through the core from top to bottom, helium is continuously heated, and the temperature increases from top to bottom. The temperature reached a maximum at the core exit position of 1032.75 K. It stated that the model can be employed to simulate the thermal hydraulic analysis for HTR. The calculation results of the loss-of-coolant, indicates t as the flow rate decreases, the coolant temperature rises gradually. When the coolant is completely lost, the temperature reaches a maximum of 1723.19 K, and it is still lower than the design limit of 1893.15 K. © 2019 American Nuclear Society. All rights reserved.

关键词： Coolants

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Exploring Geometric Chirality in Nanocrystals for Boosting Solar-to-Hydrogen Conversion

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Angewandte Chemie 2024年第45期136卷

作者： Wenlong Fu Qi Gao Chunyang Zhang Lili Tan Biao Jiang Chengyu Xiao Prof. Maochang Liu Prof. Peng-peng Wang State Key Laboratory for Mechanical Behavior of Materials Shaanxi International Research Center for Soft Matter School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China

Advancing catalyst design is pivotal for the enhancement of photocatalytic processes in renewable energy conversion. The incorporation of structural chirality into conventional inorganic solar hydrogen nanocatalysts promises a significant transformation in catalysis, a feature absent in this field. Here we unveil the unexplored potential of geometric chirality by creating a chiral composite that integrates geometric chiral Au nanoparticles (NPs) with two-dimensional C 3 N 4 nanosheets, significantly boosting photocatalytic H 2 evolution beyond the achiral counterparts. The superior performance is driven by the geometric chirality of Au NPs, which facilitates efficient charge carrier separation through the favorable C 3 N 4 -chiral Au NP interface and chiral induced spin polarization, and exploits high-activity facets within the concave surfaces of chiral Au NPs. The resulting synergistic effect leads to a remarkable increase in photocatalytic H 2 evolution, with an apparent quantum yield of 44.64 % at 400 nm. Furthermore, we explore the selective polarized photo-induced carrier separation behavior, revealing a distinct chiral-dependent photocatalytic HER performance. Our work advances the design and utilization of chiral inorganic nanostructures for superior performance in energy conversion processes.

关键词： Geometric chirality Nanoparticles Photocatalytic hydrogen evolution reaction Chiral effect

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Effect of Square Pin-Fin Twist on Thermo-Hydraulic Performance of a Rectangular Channel in Forced Convection

SSRN

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SSRN 2024年

作者： Li, Yong Zhang, Jin Zhang, Yingchun Zhang, Jiajie Wei, Jiansheng Ma, Suxia Sunden, Bengt Xie, Gongnan College of Electrical and Power Engineering Taiyuan University of Technology Shanxi Taiyuan030024 China Key Laboratory of Cleaner Intelligent Control on Coal & Electricity Ministry of Education Shanxi Taiyuan030024 China Shanxi Provincial Key Laboratory of High Efficiency Heat Storage and Low Carbon Heat Supply Shanxi Taiyuan030021 China School of Energy and Power Engineering North University of China Shanxi Taiyuan030051 China Academy of Space Information Systems Shaanxi Xi'An710000 China Lund University BS Heat Transfer and Fluid Flow AngelholmSE 22653 Sweden School of Marine Science and Technology Northwestern Polytechnical University P.O. Box 24 Xi’an710072 China

This study dealt with an experimental/numerical investigation to manage the thermo-hydraulic performance of a heat sink with square pin-fins at various twist angles and operating conditions. An experimental test platform, which utilized low-pressure air as cooling medium, was established. Steady-state liquid crystal thermography was employed to determine the Nusselt number of the heated surface. Through numerical simulations and experiments at Re = 11400-19000, it was observed that the overall performance of rectangular channels with square pin-fins was significantly better than that of flat rectangular channels. As the Reynolds number increases, the thermal resistance of the rectangular channel with square pin-fins decreased. In addition, the Nusselt number increased with an increase of the twist angle. For large twist angles (θ = 90° and θ = 180°), the friction factor reached a minimum value at Re = 15200, while the performance factor attained a maximum value at Re = 15200. For high Reynolds number (Re = 19000) and large twist angle (θ = 180°), the cooling channel with square pin-fins demonstrated optimal heat transfer and heat dissipation effects. Furthermore, twist fins at α = 0° and α = 45° exhibited distinct local heat transfer performances within the cooling channel. © 2024, The Authors. All rights reserved.

关键词： Nusselt number

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The theoretical and numerical analysis on a multi-blade liquid lead pump 27

The theoretical and numerical analysis on a multi-blade liqu...

引用

27th International Conference on Nuclear engineering: Nuclear power Saves the World!, ICONE 2019

作者： Wang, Kailin Li, Liangxing Xie, Wei Zhang, Shuangbao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi'an city710049 China

ISBN: (纸本)9784888983051

Lead or lead-alloy cooled fast reactors (LFRs) have been proved to be the most promising Generation IV reactors with high performance in neutronics, thermal hydraulics and security features. Small forced circulation modular LFRs is one of the potential candidates for LFRs development which has attracted particular attention in recent years. When lead-bismuth eutectic (LBE) is used as coolant, the primary LBE pump is a key conveying equipment, and therefore the hydraulic performance of LBE pump is great important to the safety of LFR. Motivated by improving the hydraulics performance of LBE pump, this paper presents a theoretical and computational analysis on an axial flow pump. The guide blades are set at the outlet of the impeller to eliminate the rotational motion of the liquid LBE and transform the kinetic energy of the rotational motion into pressure energy. The rotation angle of the blade is optimized based on the theoretical analysis to reduce the vortex and raise efficiency. As well, the outlet speed and pressure parameters of each part in the pump are calculated. After that, a three-dimensional model of the modified pump is established by using CFD software and the flow characteristics of LBE in the pump are simulated. Albeit the high velocity liquid LBE alloy still exists in the side of pump shroud, some erosion-related issues remain to be fully addressed. The results of the study show that the axial LBE pump could be used as a viable solution for the design of the new generation of small module reactor primary pump from a thermo-fluid dynamic point of view. © 2018-2019 by JSME

关键词： Pumps

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Three-dimensional modeling and thermal hydraulic analysis of high temperature gas-cooled reactor core 27

Three-dimensional modeling and thermal hydraulic analysis of...

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27th International Conference on Nuclear engineering: Nuclear power Saves the World!, ICONE 2019

作者： Zhang, Shuangbao Li, Liangxing Xie, Wei Wang, Kailin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi'an city710049 China

ISBN: (纸本)9784888983051

The high temperature gas-cooled reactor (HTR) is an advanced reactor with the characteristics of Generation IV nuclear energy system which has attracted wide attention due to the excellent performances of inherent safety, economy, high efficiency and low carbon environmental protection. Accurate and reliable thermal hydraulic analysis is of great significance for studying the flow and heat transfer in the core of HTR. Based on the coolant flow and heat transfer process in the core of HTR, this study establishes a three-dimensional coupled model by using CFD (Computational Fluid Dynamics) software firstly, and the flow and heat transfer process of helium coolant is simulate in the core. The temperature variation in the reactor is calculated under the conditions of steady-state operation of the HTR core, and the calculation results by the present models were compared with calculated results from the benchmark software of Thermix and the related published results. The results showed that the average temperature of the outlet section is 759.6 ℃, and the maximum relative error with the published data is 1.25%. The steady-state results under the full power conditions based on the three-dimensional model are in good agreement with the calculation data from those of THERMIX. It stated that the three-dimensional model can be employed to simulate the thermal hydraulic analysis for HTR. On this basis, the heat transfer characteristics of core is simulated under 50% full power, and the are result helpful for the operation and design of HTR. © 2018-2019 by JSME

关键词： Porous materials

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Experimental Study on the Boiling Heat Transfer Characteristics of R134a in a Helically Coiled Tube

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2019年第3期40卷 587-593页

作者： Niu, Xiao-Juan Yuan, Huai-Jie Quan, Chen Bai, Bo-Feng Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The characteristics of R134a boiling heat transfer in a vertically helically coiled tube are studied. The experimental parameters are as follows: the heat flux is 10∼60 kW•m-2, the mass flux is 195∼400 kg•m-2 •s-1, the pressure is 0.8∼1.1 MPa, and the outlet vapor quality is 0.1∼0.9. The experimental data are compared with the existing correlations of boiling heat transfer coefficient. Based on the analysis of boiling heat transfer mechanism, a new correlation for boiling heat transfer in coiled tube is proposed. The circumferential distribution characteristics of wall temperature and heat transfer coefficient are analyzed. The wall temperatures at inner and top side are relatively higher, and the heat transfer coefficients at the bottom and the outer side are relatively higher. The local heat transfer coefficients are compared with the new correlation proposed in this paper. The results show that the heat transfer coefficients at top and bottom sides can be predicted by the new correlation. However, the new correlation underestimates the heat transfer coefficient at the outer side and overestimates that at the inner side, the deviations are 16.6% and -11.9% respectively. © 2019, Science Press. All right reserved.

关键词： Heat transfer coefficients

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Numerical analysis of the axial lead-bismuth pump performace base on the different rotation speed 18

Numerical analysis of the axial lead-bismuth pump performace...

引用

18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Wang, Kailin Li, Liangxing Xie, Wei Zhang, Shuangbao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi’an city710049 China

The hydraulic performance of lead-bismuth eutectic (LBE) pump is of great importance for the safety aspects concerning lead-alloy cooled fast reactors (LFRs). To investigate the effect of different rotation speed on the performance of axial LBE pump, different rotation speed axial LBE pumps are designed by planar cascade and streamline method with the same mass flow rate and hydraulic head. Ansys BladeGen is used to establish the three-dimensional model of the axial-flow pump. CFD software (Ansys CFX) carry out numerical calculation. Numerical studies are used to compared the performance between two pumps with different rotation speed. To improve the accuracy of CFD simulation, the numerical result is verified by grid independence method and compared with theoretical calculation result. The flow velocity of the liquid LBE have great impact on the design of LBE pump because of the requirement to avoid affect of corrosion. It is found that the maximum flow velocity of low rotation speed pump is about 7.8 m/s, which is lower than the maximum flow velocity of high rotation speed pump in the case of constant volume and performance. Performance of low rotation speed pump meets the requirements of the reactor operating under long-term high load. The research results could be a viable solution used as a reference for the development of LFRs. © 2019 American Nuclear Society. All rights reserved.

关键词： Pumps

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Laminar burning velocity of gasoline and gasoline surrogates under various pressures and temperatures 12

Laminar burning velocity of gasoline and gasoline surrogates...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Hu, Erjiang Xu, Zhaohua Gao, Zhenhua Huang, Zuohua Stake Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Shaan Xi710049 China

The outwardly propagating spherical flame method was used to measure the laminar burning velocity of a commercial gasoline fuel having RON of 92 and gasoline surrogate. Measurements were conducted at the equivalence ratio of 0.8 to 1.5, initial temperatures of 358 K, 403 K, and 448 K and initial pressures of 1 atm, 2 atm and 5atm in a constant volume bomb. The surrogate of primary reference fuel (PRF-92, 92% iso-octane + 8% n-heptane) and toluene reference fuel (TRF-92, 16.69% iso-octane + 22.65% n-heptane + 60.66% toluene) were proposed to match the laminar burning velocity of gasoline (CNPC 92#). It could be found that the TRF-92 was able to successfully reproduce the laminar burning velocity of the gasoline under various experimental conditions. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Gasoline

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Thermal Simulation for a Mechanical Spindle With External Cooler Across Grease Coated Interface

Research Square

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Research Square 2021年

作者： Zhao, Liang Lei, Mohan Ren, Hongdi Wang, Jinshi Wang, Shuai Li, Ben Q. Yang, Jun Mei, Xuesong Xi'an Jiaotong University China State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'An710049 China Shaanxi Key Laboratory of Intelligent Robots Xi'an Jiaotong University Xi'An710049 China School of Mechanical and Precision Instrument Engineering Xi'an University of Technology 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering College of Engineering and Computer Science University of Michigan MI48128 United States

Spindles in precision boring machine often work in low speed and heavy load without internal cooling, and the thermal error is nonnegligible. So an external cooling system was designed, and the effectiveness of the designed scheme needs to be preliminarily verified by simulation before building the cooling system. Thermal simulations of the spindle with an external cooler require calculating the thermal resistance of the thermal grease-coated interface between the cooler and spindle. Models describing the contact thermal resistance and total thermal resistance for metal contact filled with silicone grease based on solid-liquid interface force equivalence were described in this paper, and experiments were also conducted to verify the accuracy of these models. The contact thermal resistances between the cast iron/copper and silicone grease on flat or arc surfaces were calculated, and the bulk thermal resistance of the silicone grease layer was calculated. The total heat transferred between the cooler and the silicone grease-coated interface of the spindle were calculated. Heat transfer and heat generation in the spindle were calculated, and a finite element model was established to verify the effectiveness of the designed external cooling scheme. Finally, results from experiments for the spindle in different conditions show that the external cooling system decreases the time to reach thermal equilibrium by more than 60%. The RMSE of the simulated thermal elongation is less than 5.7044 μm when the rotating speed of 3000 rpm, and is less than 3.9714 μm when the rotating speed is 1500 rpm. © 2021, CC BY.

关键词： Cooling

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Review on development of carbon nanotube field emission cathode for space propulsion systems

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High Voltage 2020年第4期5卷 409-415页

作者： Chao Huo Feng Liang An-bang Sun Science and Technology on Combustion Internal Flow and Thermal-structure LaboratorySchool of AstronauticsNorthwestern Polytechnical UniversityXi'anShaanxiPeople's Republic of China Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunmingPeople's Republic of China State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical EngineeringXi'an Jiaotong UniversityXi'an 710049People's Republic of China

In recent years,small-size,low-weight aerospace propulsion systems have developed rapidly for space exploration,on-orbit scientific instruments and extra space missions,while additional electron emission devices are commonly required in those propulsion *** nanotube(CNT)based field emission cathodes exhibit extraordinary field emission properties and are regarded to be an ideal alternative of conventional thermionic or hollow *** this study,the authors give an overview of present status of researches on CNT-based electron emission cathodes for utilising as neutralisers or electron sources particularly in space electric propulsion systems,the theory and characteristics of CNT are also ***,challenges,problems and possible solutions before actual applications of CNT in a space mission are discussed accordingly.

关键词： field neutral emission

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