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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryton Cycle Coaxial Integrated Unit

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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryto...

Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Xiaokang Xu Yi Yang Jiangfeng Wang Juwei Lou Liangqi Chen State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and Technology National University of Defense Technology Changsha China

The rotor system plays a very important role in supercritical carbon dioxide Brayton cycle system, and its dynamic problem will directly affect the motion stability and safety of the whole unit. In this paper, the rotor dynamic model of supercritical CO 2 coaxial unit is established by finite element method, and the critical speed, modal shape and unbalance response of the rotor are studied. The first seven critical speed of the rotor and the first seven natural frequency of the rotor at the working speed are calculated. The bending modal of the rotor and the position where the rotor amplitude is the largest are analyzed, which can provide reference for the optimization design of the rotor stability. The influences of mass unbalances at the operational speed of rotor are analyzed. The research can provide some suggestions for the optimal design and actual operation of the supercritical CO 2 coaxial integrated unit.

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Transient Thermoelectric Characteristics of the Principle Prototype for the Heat Pipe Cooled Nuclear Silent Themoelectirc Reactor (Nuster)

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SSRN 2023年

作者： Guo, Kailun Zhang, Yin Lin, Xingyang Huang, Jinlu Wang, Chenglong Qiu, Suizheng Tian, Wenxi 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

This paper proposes an optimized design for the Heat Pipe ThermoElectric Generator(HPTEG) principle prototype. The refined scheme adopts high-temperature sodium heat pipes as heat transfer elements to enhance the overall operating temperature of the device. It adopts Half-Hessler(HH) alloy ThermoElectric Generator(TEG) arranged on the upper and lower sides of the heat exchanger to enhance the thermoelectric conversion efficiency of the device. A heat pipe dynamic conduction model is established to simulate the start-up process of the sodium heat pipe. A TEG model is developed, which is able to simulate the three-dimensional thermoelectric properties of the TEG. The numerical simulation platform is used to analyze the steady-state and transient thermoelectric properties of the refined HPTEG prototype. This study provides data support for the subsequent design modification of the future HPTEG principle prototype and provides ideas for the 3D transient calculations of the solid-state heat pipe reactors. © 2023, The Authors. All rights reserved.

关键词： Heat pipes

Electromagnetic Effects and Accurate Wall-Temperature Measurement Method Under Directly Electric Heating Mode

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SSRN 2022年

作者： Lei, Xianliang Liu, Yunfan Liu, Shuhan Li, Debiao Gou, Lingtong Li, Yusheng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

By directly imposed electrical energy on metal materials with low voltage but high current to generate Joule heat is an effective energy conversion method. The corresponding temperature will quickly reach the predetermined value. It is also an effective way to achieve homogeneous heating or local non-uniform heating in the heterogeneous conductive elements, thus directly electric heating is widely used in scientific experiments and industrial practices. However, different direct Electrical heating method (i.e., Direct-Current or Alternating Current heating) will lead to different power losses and the interference on the sensor, results in inconsistent temperature distribution or inaccurate temperature, even under the condition with power frequency (f= 50 Hz or 60 Hz). In the present paper, the skin effect and eddy current in different metal materials with variable frequency and different section-shapes have been analyzed by electromagnetic coupling simulation. Meanwhile, two comparative experimental investigations on temperature measurement methods with DC and AC heating have been implemented. It is found that the measured temperature by AC heating is always lower than that of DC heating effected by skin effect and mutual inductance effect, the skin depth in four common used materials is: Iron © 2022, The Authors. All rights reserved.

关键词： Temperature measurement

Sensitively Detection of Ascorbic Acid in Orange Samples with Ionic Liquid Functionalized Carbon Dots and Lanthanide Complexes

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SSRN 2024年

作者： Li, Ying Xia, Ji-Ji Lu, Jia-Zhen Wang, Zi-Long Wang, Mi-Tang School of Materials and Chemistry University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

In the food industry, ascorbic acid (AA) is widely used as an antioxidant. However, the concentration of AA is influenced by various factors, including temperature, time, and pH value during food preparation and storage, leading to its instability in content. This makes the accurate detection of AA content particularly important. Precise determination of AA content in food and pharmaceuticals is crucial for ensuring the adequate intake of essential vitamins and maintaining good health. Herein, we have developed a successful preparation method of an imidazole-based ionic liquid functionalized CDs hybrids APM-CDs. A novel photo functional hybrid probe Eu3+@APM-CDs was obtained via an ion-exchange reaction between APM-CDs and lanthanide complex Eu(DPA)3. The obtained hybrid probe was extensively characterized in detail. What’s more, the results show that the FL intensity of Eu3+@APM-CDs has a good linear response to AA concentrations in the range of 0-500 μM (R2 = 0.99), with a detection limit of 80 nM. The fluorescence probe demonstrates good selectivity and sensitivity toward AA and has the potential for significant application in AA detection by simplifying procedures and reducing interference from impurities. © 2024, The Authors. All rights reserved.

关键词： Probes

Depth from Defocus Technique for High Number Densities and Non-Spherical Particles

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SSRN 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Thermal-Hydraulic Characteristics of Helical Cruciform Single Rod Based on Cfd Investigation

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SSRN 2023年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Wang, Xinan Tian, Wenxi Qiu, Suizheng Su, Guanghui 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

The helical cruciform fuel (HCF) takes advantages of strong mixing effects, self-supporting features, and strengthened heat transfer, potential to increase the fuel performance in nuclear reactors. In this work, hydraulic resistance and heat transfer characteristics of an HCF single rod cooled by water were studied based on CFD simulation. Various turbulent models were compared based on experimental data. The velocity field, transverse velocity, wall temperature, and fluid temperature distribution were obtained to discuss influences of geometric sizes on the fuel performance. After 3/8 of the pitch, flow was fully developed. The friction factor and surface heat transfer coefficient were higher with a shorter twist pitch owing to stronger mixing effect while they kept unchanged with variable cross-section sizes but a fixed equivalent diameter. Correlations of friction factor and surface heat transfer coefficient were proposed considering geometric modified coefficients based on a geometric dimensionless number, which were validated with new geometric cases. © 2023, The Authors. All rights reserved.

关键词： Heat transfer coefficients

Experimental Study on flow and Heat Transfer of Medium-Prandtl-Number Fluid Along a Hexagonal Helical Cruciform Seven-Rods

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SSRN 2023年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui 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

A novel type of nuclear fuel named helical cruciform fuel may realize self-supporting for adjacent elements and improve heat transfer, both of which contribute to increasing the power density of the reactor. The flow and heat transfer characteristics of a hexagonal helical cruciform seven-rod bundle were experimentally investigated in the present work. 200 sets of isothermal frictional resistance experiments and 199 sets of heat transfer experiments were finished. The laminar flow region (200 © 2023, The Authors. All rights reserved.

关键词： Reynolds number

Development and Validation of Fully-Coupled Subchannel Analysis Code for Lmr within the Moose Framework

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SSRN 2023年

作者： Zhu, Xinyang Chen, Ronghua Wang, Jinshun Niu, Yuhang Wu, Yingwei Zhang, Dalin 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

As one of the Gen IV advanced reactors, liquid metal reactor(LMR) holds promising prospects for its high fuel efficiency and excellent inherent safety performance. Owing to its complex working conditions and ultra-high operating temperature, a thermal-hydraulic analysis of the reactor core is gradually playing a bigger role in recent years. Therefore, a subchannel code FLARE for LMRs is developed within the MOOSE ***, a hybrid discretization approach involving DG and FEM as well as the JFNK method are employed to solve the equations in a fully-coupled way. To validate the computational accuracy and convergence of FLARE code, comparisons between the calculation values of FLARE, those of other programs and the experimental data are performed using 7-pin, 19-pin and 37-pin assembly experiments. The computational results indicate a good agreement between FLARE, experimental values, and other programs. In conclusion, FLARE code possesses the capability to accurately analyze LMR core. © 2023, The Authors. All rights reserved.

关键词： Reactor cores

Chemical Kinetics Simulation on Nitrogen Migration Characteristics During Co-Combustion of Ammonia and Coal Under Deeply Fuel-Air Multistage Conditions

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SSRN 2024年

作者： Dai, Liangxu Wang, Chang'an Hou, Yujie Ma, Guowei Chen, Yongxu Hurera, Abu Zhou, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China China Energy Science and Technology Research Institute Co. Ltd. Nanjing210046 China

mmonia, a carbon-free fuel, is attracting an ever-increasing attention. Coal/ammonia co-combustion in coal-fired power plants is considered an effective and fast approach to achieving the global decarbonization goal. However, one bottleneck of the utilization of ammonia fuel is the possible increased NOx emissions. The supply strategy of ammonia can affect the reduction of NOx by NH3. Few studies have explored the influence of ratios of ammonia as a secondary fuel and the secondary air volume on NOx emissions, which could be effective methods to reduce pollution. In this work, a chemical kinetics model was established to study the NOx behaviors during coal/NH3 co-firing in deeply fuel-air multistage conditions. The effects of the ammonia distribution strategies such as the ratio of NH3 as a secondary fuel, the injection position of secondary fuel, and corresponding air distribution with different NH3 co-firing ratios (CR-NH3) on the ammonia reactivity for NOx-reduction were studied. The results show that ammonia should be used as a primary fuel entering the main combustion zone under small CR-NH3 conditions to mitigate the NOx emissions;otherwise, ammonia is inclined to be used as a secondary fuel entering the reduction zone under large CR-NH3 conditions. NOx generation is also found to primarily occur in the burnout zone in fuel-air multistage combustion. Thus, the burnout zone should be given priority to decrease the NOx emissions. With the delay of secondary fuel injection in the reduction zone, the escaping ammonia keeps increasing in the outlet of the reduction zone. Then it is completely burned in the burnout zone, which leads to an increase in NOx emissions. The volume flow rate of NOx shows a downward trend on the whole with the ratio of secondary air increased. The air distribution can alter the function of the reduction zone in both generating and eliminating NO. The findings can provide some guidance to effectively decrease NOx emissions in coal/NH3 co-fi

关键词： Coal