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POD analysis on vortical structures in MVG wake by Liutex core line identification

Journal of Hydrodynamics 2020年第3期32卷 497-509页

作者： Xiang-rui Dong Xiao-shu Cai Yinlin Dong Chaoqun Liu School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering Shanghai 200093China Department of Mathematics University of Central ArkansasConway 72035USA Department of Mathematics University of Texas at ArlingtonArlington 76019USA

The Liutex core line method, first combined with the snapshot proper orthogonal decomposition (POD), is utilized in a supersonic micro-vortex generator (MVG) wake flow at Ma = 2.5 and Reθ = 5 760 to reveal the physical significance of each POD mode of the flow field. Compared with other scalar-based vortex identification methods, the Liutex core line identification is verified to be the most appropriate approach that is threshold-free and provides full information of a fluid rotation motion. Meanwhile, the Liutex integration is employed to quantitatively track the evolution of the vortices in MVG wake and is applied to the determination of the effective control section of the MVG wake for the optimization study of MVG design. The physical mechanism of each POD mode for multi-scale and multi-frequency vortical structures is investigated by using Liutex core line identification to give some revelations. For the mean mode (mode 0) indicating the time-averaged velocity flowfield of the MVG wake flow, a pair of primary counter-rotating streamwise vortices and another pair of secondary vortices is uniquely identified by two pairs of Liutex core lines with Liutex magnitude. In contrast, mode 1 is featured by a fluctuated roll-up motion of streamwise vortex, and the streamwise component of the MVG wake is demonstrated to be dominant in terms of the total kinetic energy contribution. Meanwhile, a dominant shedding frequency of St = 0.072 is detected from the temporal behavior of mode 2, which has the organized arc-shaped vortex structures shedding from MVG induced by the K-H instability. Additionally, mode 4 subjects to low-frequency oscillations of the wall vortices and thus takes a relatively lower frequency of St = 0.044.

关键词： Proper orthogonal decomposition(POD) vortex identification Liutex vortex core lines micro-vortex generator(MVG)

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Development and Verification of Safety Analysis Code to Model and Simulate Steam power Conversion System in Sodium-Cooled Fast Reactor

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SSRN 2023年

作者： Liu, Shuo Jin, Zhao Wang, Chenglong Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui Yang, Jun School of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Institute of Atomic Energy Beijing102413 China

Sodium-cooled fast reactor (SFR) is one of the most promising generation IV reactor type. SFR system is composed of three heat transfer circuits. SFR will generate electricity, which requires accuracy prediction of steam power conversion system. Therefore, a one-dimensional thermal-hydraulic analysis code of the steam power conversion system of SFR has been developed. A modular modeling method was applied. Each equipment is packaged as a separate module. The system model can be obtained by connecting modules to achieve flexible modeling. Compared with RELAP5, the code uses a general algorithm to solve ODE, which enhances the universality of code. The model is verified with design results of Daya Bay Nuclear power Plant and BN-600 steam generator. The maximum relative errors for pressure and temperature are 5.44% and 2.40%, respectively. It is proven that the code developed can be used in the analysis and design the steam power conversion system. The steady-state analysis of SFR steam power conversion circuit is carried out. The design could provide a reference for the future development of steam power conversion system in SFR. © 2023, The Authors. All rights reserved.

关键词： Sodium-cooled fast reactors

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Dynamic Modeling of Steam power Conversion System in Sodium-Cooled Fast Reactor

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SSRN 2023年

作者： Liu, Shuo Jin, Zhao Wang, Chenglong Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, G.H. Yang, Jun School of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Institute of Atomic Energy Beijing102413 China

Sodium-cooled fast reactor (SFR) is the most promising generation IV reactor type. SFR systems are composed of three heat transfer circuits. Currently, research on steam power conversion system is scarce because of complex structure. Therefore, a one-dimensional thermal-hydraulic analysis code of the steam power conversion system of SFR has been developed. Models of main components have been established, including once-through steam generator (OTSG), turbine, deaerator, feedwater heater, condenser, pump and moisture separator reheater (MSR). The model is verified with design results of Daya Bay Nuclear power Plant and BN-600 steam generator. The maximum relative errors for pressure and temperature are 5.44% and 2.40%, respectively. It is proven that the code developed can analysis and design the steam power conversion system. The steady-state analysis of SFR steam power conversion circuit is carried out. The design could provide a reference for the future development of steam power conversion system in SFR. © 2023, The Authors. All rights reserved.

关键词： Sodium-cooled fast reactors

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Experimental Study of Air-Steam–Mixture Condensation Underneath Containment Vessel Surface

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Nuclear Science and engineering 2021年第8期195卷 838-852页

作者： Bing Tan W. X. Tian R. H. Chen S. Z. Qiu G. H. Su a Xi’an Jiaotong University School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering 28 Xianning West Road Xi’an 710049 Chinab South China University of Technology School of Electric Power Guangzhou 510640 China a Xi’an Jiaotong University School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering 28 Xianning West Road Xi’an 710049 China

Aiming at studying the condensate flow phenomenon and air-steam–mixture condensation heat transfer underneath a containment vessel surface, a test bench was constructed. The plate dimension was 1.5 × 0.6 m, with Carbozinc 11 coating on the surface, suspended in a pressure vessel with 2.5-m diameter and 4.5-m height. The air-steam mixture was condensed on an inclined plate through natural convection mode and jet mode. By observing flow behavior on the plate through a viewport, four basic regimes were obtained as the inclination angle gradually increased: droplet, droplet to rivulet transition, developed rivulet, and uniform film. During the experiment, we observed a steam atomization phenomenon; therefore, the model predicted better with the atomization effect considered. A simple formula from the condensation data is proposed when the air mole fraction is small. The error between the experimental results and the predicted data is within 25%.

关键词： Passive cooling system steam condensation flow regime new empirical correlation

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Two-Phase flow Dynamics in the Coupling Region of Gas Diffusion Layer and Patterned Wettability Metal Foam flow Field in Proton Exchange Membrane Fuel Cells

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SSRN 2024年

作者： Lv, Xuecheng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Gao, Linsong Lyu, Jizu Li, Yang Yang, Yunjie Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

In this study, the 3D structures of the gas diffusion layer (GDL) and metal foam flow field (MFF) in proton exchange membrane fuel cells (PEMFCs) were reconstructed by X-ray computed tomography, and the two-phase flow in the GDL-MFF coupling region was simulated by phase-field Lattice Boltzmann method (LBM). A comparative analysis of the two-phase flow characteristics was conducted between hydrophobic metal foam (HMF) and patterned wettable metal foam (PWMF). The effect of the wettability and size of the hydrophilic regions in PWMF was investigated. The results demonstrate that PWMF offers several advantages, including rapid removal of liquid water at the GDL-MFF interface, low liquid water coverage at the GDL-MFF interface, enhanced vertical gas convection in the GDL, low and stable pressure drop in the MFF, stable gas turbulent intensity in the MFF, and a more uniform gas velocity distribution. However, PWMF may slow down the transport of liquid water from the GDL to the MFF, increase the water saturation in the GDL, and reduce the drainage rate of the flow field. Proper adjustment of the contact angle and size of the hydrophilic regions in PWMF can alleviate these drawbacks. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

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Dynamic Analysis and Optimization of Heat Transfer Performance During Electrospray Cooling with Ethanol-R141b Mixture

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SSRN 2022年

作者： Tian, Jiameng Kong, Lingwen Li, Bufa Wang, Junfeng Chen, Bin Xiong, Junhui School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Zhejiang Ningbo315201 China

Electrospray (ES) cooling that relies on Coulomb forces for energy-efficient liquid atomization is promising to meet the requirement of high-heat-flux thermal dissipation for micro-sized electronics under relative low... 详细信息

关键词： Ethanol

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Xct Images-Based Modeling for Elucidating Electrochemical Inert Phase-Dependent Multiscale Electrode Kinetic Behaviors

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SSRN 2024年

作者： Huang, Heng Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu Hu, Chengzhi Gao, Linsong Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China

The structure and spatial distribution of electrochemical inert phase (EIP) in electrodes are highly heterogeneous, which deteriorates the performance of electrodes under harsh operating conditions such as high-rate or low-temperature. In this work, with the assist of digitally processed X-ray computed tomography (XCT) for charactering images of LiNi0.5Co0.2Mn0.3 electrode, the electrodes with different EIP geometries are reconstructed, and the dependence of electrode performance degradation on EIP is elucidated from a multiscale perspective. Physical structure characterization and 3D microstructure resolved model reveal that, compared to 3D bulk EIP (B-EIP), 2D film EIP (F-EIP) tends to cover active surface of active material (AM), which exacerbates the heterogeneous electrode lithiation reaction. The decrease of AM active surface area makes the state of lithiation (SOL) of particles closely related to their active specific surface area (αa). The temperature sensitivity of electrodes at low temperatures exacerbates the hazard of αa loss, allowing heterogeneous reaction transfer between particles. The Biot number (Bi) evaluates the competing mechanisms between interfacial reactions and bulk diffusion of particles, and the reaction rate at the particle/electrolyte interface is accelerated in high content EIP electrodes, allowing the Li concentration gradient within the particles to be dominated by interfacial reactions. Finally, the electrochemistry and heat generation from particle to electrode level in high area-loaded electrodes are explored, showing that the lithium ion diffusion in the pores controls the interfacial reactions and heat transport behavior. The aggregated high flux reactions and localized hot spots aggravate the heterogeneous degradation and side reactions of the electrode. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Solution chemistry back‐contact FTO/hematite interface engineering for efficient photocatalytic water oxidation

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Chinese Journal of Catalysis 2022年第5期43卷 1247-1257页

作者： Karen Cristina Bedin Beatriz Mouriño Ingrid Rodríguez-Gutiérrez João Batista Souza Junior Gabriel Trindade dos Santos Jefferson Bettini Carlos Alberto Rodrigues Costa Lionel Vayssieres Flavio Leandro Souza The National Nanotechnology Laboratory(LNNANO) Brazilian Center for Research in Energy and Materials(CNPEM)Campinas 13083‐970Brazil Centro de Ciências Naturais e Humanas(CCNH) Federal University of ABC(UFABC)Santo André09210580Brazil Federal University of Rio Grande do Sul(UFRGS) Rio Grande do SulBrazil International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

This work describes a simple yet powerful scalable solution chemistry strategy to create back‐contact rich interfaces between substrates such as commercial transparent conducting fluorine‐doped tin oxide coated glass(FTO)and photoactive thin films such as hematite for low‐cost water oxidation ***‐resolution electron microscopy(SEM,TEM,STEM),atomic force microscopy(AFM),elemental chemical mapping(EELS,EDS)and photoelectrochemical(PEC)investigations reveal that the mechanical stress,lattice mismatch,electron energy barrier,and voids between FTO and hematite at the back‐contact interface as well as short‐circuit and detrimental reaction between FTO and the electrolyte can be alleviated by engineering the chemical composition of the precursor solutions,thus increasing the overall efficiency of these low‐cost photoanodes for water oxidation reaction for a clean and sustainable generation of hydrogen from PEC water‐*** findings are of significant importance to improve the charge collection efficiency by minimizing electron‐hole recombination observed at back‐contact interfaces and grain boundaries in mesoporous electrodes,thus improving the overall efficiency and scalability of low‐cost PEC water splitting devices.

关键词： Nanostructure Iron oxide Water oxidation Photoanode Surface engineering Chemical synthesis

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Design of Solar Dish/Stirling Rotation Control System with Dual Axis Solar Tracker

Design of Solar Dish/Stirling Rotation Control System with D...

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第40届中国控制会议

作者： Zhijie Zhou Jiaxing Chen Zhuohuan Hu Daolin Nie Chulin Wen School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering

This paper presents a dual-axis tracking control system for a Small Dish/Stirling System（SDSS）. The sun trajectory tracking algorithm was applied for all-weather accurate sun tracking. The rotating devices consist of two brushless DC motors,an encoder, an inclinator and slewing drivers. The dual-axis solar tracker was applied to improve the system’s *** results show that the system performance is reliable, and the average sun-tracking accuracy achieves 0.278° and 0.321° for azimuth and zenith respectively.

关键词： Dish/Stirling system Solar tracking Dual axis DC motor

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Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

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SSRN 2024年

作者： Wang, Cui Jin, Hui School of Water and Environment Chang'an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang'an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Ministry of Education of China Chongqing University Chongqing400044 China

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters, including gasification temperature, mass flowrate of preheated water, biomass concentration, on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance of the system was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss under different conditions, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, higher biomass concentration and more preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was primarily affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached about 58.3% at 550℃, biomass concentration of 33%, preheated water mass flowrate of 900 kg·h-1 © 2024, The Authors. All rights reserved.

关键词： Biomass

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