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Bubble oscillation and effects of dynamic behaviors on forces and mass transfer in photoelectrochemical water splitting

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Physical Review Fluids 2024年第11期9卷 114305-114305页

作者： Yonglu She Qiang Xu Tengfei Nie Xinyi Luo Mengsha Wang Xingmiao Ye Dengwei Jing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The evolution and coverage of bubbles resulting from gas evolution at the reaction interface significantly impact mass transfer and the flow field within the photoelectrochemical water splitting system, posing a significant obstacle to overcoming the efficiency bottleneck of photoelectrochemical water splitting. In situ bubble observation can be realized via a coupled experimental system combining electrochemical measurements and high-speed imaging. The results indicate that bubble growth behavior correlates with system temperature and operating voltage; that is, the bubbles grow in an oscillating state on the electrode surface at the low operating voltage and high system temperature. Besides, the deviation amplitude of oscillating bubbles increases with system temperature yet decreases with operating voltage. The results indicate that the time coefficient of the growing bubble decreases, while the growth rate and gas evolution efficiency of the bubble increase with the increase of oscillating amplitude in the horizontal direction. The study of dynamic behaviors between the oscillating bubble and the contacted electrode reveals that the bubble oscillation is characterized by the periodic contraction and extension of the triple line. The mass transfer model of concentration boundary layer and the force model of oscillating bubble are constructed based on the interaction between the bubbles and the surrounding flow field. The mass transfer model has considered the microconvection caused by single-phase natural convection, gas-liquid interface expansion, and the oscillation of bubbles. Then through the force balance model, the solutal Marangoni force is found to gradually increase as the contact line extends outward.

关键词： Bubble dynamics Contact line dynamics Marangoni convection Microbubbles multiphase flows

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Study on startup characteristic of a supercritical carbon dioxide Brayton cycle coupled with heat pipe cooled reactor 20

Study on startup characteristic of a supercritical carbon di...

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20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023

作者： Wang, Zheng Zhang, Minghui Xu, Shihao Gou, Junli Shan, Jianqiang State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780894487934

Nuclear energy is a viable choice for Unmanned Undersea Vehicles (UUVs) due to its high density and long operation life. However, traditional PWRs aren't suited to underwater working environments. To provide a safe and reliable power source for UUV, a new nuclear power plant coupled with the supercritical CO2 Brayton cycle and heat pipe cooled reactor is proposed. This provides the advantages of high reliability, high safety and high expansion ability. In this work, a simulation code for the new nuclear power plant is developed, which includes a reactor kinetics model, a core heat conduction model, a two-dimensional heat pipe network model, and a closeCO2 Brayton cycle model. In order to verify the accuracy of the model, the date of the experiment is compared with the model. And the design value of the new nuclear power plant has been modeled by this code. Meanwhile, the control strategies for start-up of the new nuclear power plant are proposed, including core startup, heat pipe startup and supercritical carbon dioxide Brayton loop startup. By utilizing the control strategies, the code has researched the operational characteristics of the start-up of heat pipe-cooled reactors. The development of this code provides a reference for the new nuclear power plant. © 2023 Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. All rights reserved.

关键词： Brayton cycle

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Data-Driven Surrogate Model for the Dynamic Characteristics of Supercritical Units

Data-Driven Surrogate Model for the Dynamic Characteristics ...

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2024 Boao New power System International Forum - power System and New Energy Technology Innovation Forum, NPSIF 2024

作者： Dong, Shuai Zheng, An Jiang, Junyao Gao, Wei Liu, Ming Huaneng Yimin Coal-Power Co. Ltd. Hulunbuir021130 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9798331504557

Coal-fired power generation units are characterized by large inertia, strong coupling, and high delay, making dynamic characteristic modeling inherently complex and computationally intensive. To address this, this paper utilizes GSE software to explore the dynamic characteristics of supercritical units. Data-driven approaches are then employed to develop surrogate model for these dynamics, comparing neural networks and support vector regression methods in the process. The study indicates that the surrogate model achieves a relative prediction error of less than 1% for live steam temperature, reheater steam outlet temperature, and power output. For live steam pressure and reheater steam outlet pressure, the model maintains a relative error within 10%. © 2024 IEEE.

关键词： Support vector regression

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Unconventional energetics of small vacancy clusters in BCC high-entropy alloy Nb_(0.75)ZrTiV_(0.5)

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Journal of Materials Science & Technology 2023年第15期146卷 61-71页

作者： Tan Shi Xi Qiu Yundi Zhou Sixin Lyu Jing Li Dan Sun Qing Peng Yong Xin Chenyang Lu School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China Nuclear Power Institute of China Chengdu 610213China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The stability of small vacancy clusters including divacancy,trivacancy and tetravacancy has been studied in body-centered cubic high-entropy alloy Nb_(0.75)ZrTiV_(0.5) in structures of random solid solution and short-range order by first-principles calculations and molecular dynamics *** from conventional body-centered cubic metals,the tightly bound configurations have a lower structural stability and are not preferred energetically in the studied high-entropy *** of vacancy configurations leads to vacancy-atom exchanges that favor less compact *** formation energy of small vacancy clusters is much smaller than its constituent elements of Nb and V due to the large structural adjustment induced by severe local lattice *** difference in local lattice distortion and elemental arrangement in the vacancy neighborhood leads to significant site-to-site variation in vacancy cluster energy and *** formation energy has a strong correlation with the local energy state of the vacancy configuration and the extent of structural *** to random solid solution,the structure of short-range order has a higher stability for the most compact cluster configurations and tends to have higher vacancy cluster formation *** to classical molecular dynamics simulations of cluster diffusion at high temperature,the studied high-entropy alloy has a higher probability of cluster dissociation compared to Nb and *** unconventional energetics of small vacancy clusters is expected to have a profound impact on their generation,diffusion,dissociation,coalescence,as well as the defect microstructure evolution during irradiation.

关键词： Refractory high-entropy alloys Small vacancy clusters First-principles calculations Defect energetics Radiation defect evolution

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Temperature dependence photoluminescence properties of ZnSe-based core-shell quantum dots

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Optics Express 2025年第11期33卷 22588-22597页

作者： Zhang, Tingting Ma, Qing Li, Qingping Huang, Lanting Feng, Yuqiong Duan, Hongwei Chen, Xinlei Li, Qinghua Jin, Xiao Bai, Jinke Xu, Bing Key Laboratory of Environmentally Friendly Functional Materials and Devices School of Physics Science and Technology Lingnan Normal University Guangdong Zhanjiang524048 China School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Department of Materials and Chemical Engineering Taiyuan University Taiyuan030032 China

Heavy metal-free ZnSe-based core-shell quantum dots (QDs) are promising emitting material for achieving violet-blue luminescence. Investigating the temperature-dependent variations in the photoluminescence (PL) properties of ZnSe-based QDs will enhance our understanding of the intrinsic factors that influence their diverse luminescence characteristics. Here we select the optimally synthesized ZnSe core QDs with three diameters (4.1, 5.2, and 8.3 nm) and ZnSe/ZnS core-shell QDs to study their temperature-dependent photoluminescence properties. As the sample temperature is increased, the PL intensity decreases, the emission energy redshifts, and the spectral become broader. We observe a reduction in the exciton-longitudinal optical (LO)-phonon coupling constant from 21.7 meV to 16.1 meV as the diameter of ZnSe core QDs increased from 4.1 nm to 8.3 nm. This decrease is associated with a narrower homogeneous broadening of the emission spectrum. Besides, the epitaxial growth of a ZnS wide bandgap shells onto the ZnSe core QDs can effectively isolate the photogenerated excitons away from the inorganic-organic interface, thus reducing the PL peak width and increasing the exciton binding energy of the QDs. Our research provides a valuable addition to the existing studies on the photoluminescence properties of ZnSe-based core-shell QDs. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Atomic emission spectroscopy

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Operando modeling and measurements:powerful tools for revealing the mechanism of alkali carbonate-based sorbents for CO_(2)capture in real conditions

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Frontiers in Energy 2023年第3期17卷 380-389页

作者： Tianyi CAI Mengshi WANG Xiaoping CHEN Ye WU Jiliang MA Wu ZHOU School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Energy Thermal Conversion and Control of the Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Key Laboratory of Thermal Control of Electronic Equipment and Advanced Combustion Laboratory of the Ministry of Industry and Information Technology School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

Alkalicarbonate-based sorbents(ACSs),including Na_(2)CO_(3)-and K2CO_(3)-based sorbents,are promising for CO_(2)***,the complex sorbent components and operation conditions lead to the versatile kinetics of CO_(2)sorption on these *** paper proposed that operando modeling and measurements are powerful tools to understand the mechanism of sorbents in real operating conditions,facilitating the sorbent development,reactor design,and operation parameter *** reviewed the theoretical simulation achievements during the development of *** elucidated the findings obtained by utilizing density functional theory(DFT)calculations,ab initio molecular dynamics(AIMD)simulations,and classical molecular dynamics(CMD)simulations as *** hygroscopicity of sorbent and the humidity of gas flow are crucial to shifting the carbonation reaction from the gas-solid mode to the gas-liquid mode,boosting the ***,it briefly introduced a machine learning(ML)approach as a promising method to aid sorbent ***,it demonstrated a conceptual compact operando measurement system in order to understand the behavior of ACSs in the real operation *** proposed measurement system includes a micro fluidizedbed(MFB)reactor for kinetic analysis,a multi-camera sub-system for 3D particle movement tracking,and a combined Raman and IR sub-system for solid/gas components and temperature *** is believed that this system is useful to evaluate the real-time sorbent performance,validating the theoretical prediction and promoting the industrial scale-up of ACSs for CO_(2)capture.

关键词： CO_(2)capture carbonation theoretical modeling operando techniques reaction visualization

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Experimental investigation on separation characteristics of axial cyclone separator

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Science China(Technological Sciences) 2023年第11期66卷 3231-3244页

作者： WANG JinZhi WANG YeChun HAN JinZai XU Qiang XIE XiangDong PAN YingXiu GUO LieJin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Xinjin Weihua Institute of Clean Energy Research Foshan 528216China Aero Engine Corporation of China(AECC)Shenyang Engine Research Institute Shenyang 110015China

Axial cyclone separator has been widely applied in chemical production as an efficient gas-liquid separation *** this study,a new axial cyclone separator with integrated swirler and exhaust pipe is designed to achieve the development goal of compact structure for advanced engine,and the distribution characteristics of swirling flow patterns as well as the variation in separation characteristics are investigated under slug flow *** on flow visualizations and fluctuation characteristics of pressure signals,three typical flow patterns,namely,slug flow,swirling intermittent flow,and swirling annular flow,in the horizontal swirling separation flow are *** is investigated how the inlet conditions affect the separation characteristic *** separation purity and extreme points of the air separation efficiency are independent of the inlet liquid flow *** separation pressure drop is quadratically related to the inlet air flow *** on the drift-flux model and other methods,the prediction methods for the air separation efficiency and pressure drop are proposed,and the prediction accuracy is within±20%,which may provide instructions for the practical application of axial cyclone separator.

关键词： axial cyclone separation gas-liquid two-phase flow flow pattern in the swirling flow separation characteristics

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Porous fixed-bed photoreactor for boosting C-C coupling in photocatalytic CO_(2)reduction

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eScience 2022年第4期2卷 428-437页

作者： Shengjie Bai Haoran Qiu Mengmeng Song Guiwei He Feng Wang Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'anShaanxi710049China

Solar-driven CO_(2)conversion to chemical fuels in an aqueous solution is restricted not only by photocatalysts but also by mass ***,a regulatable three-phase interface on a porous fixed-bed is constructed for efficient C-C coupling in photocatalytic CO_(2)*** photocatalytic results show that∼90%selectivity towards C^(2+)products is obtained by a Cu/Cd_(0.5)Zn_(0.5)S photocatalyst,with a yield of 6.54μmol/h(an irradiation area of 0.785 cm^(2)),while only 0.94μmol/h(an irradiation area of 19.625 cm^(2))is achieved with a commonly used suspension photocatalytic *** find that under the same CO_(2)feed rate,the local CO_(2)concentration in this porous fixed-bed photoreactor is obviously higher than in the suspension *** larger local CO_(2)coverage derived from a higher CO_(2)supply and aggregation enhances the C-C coupling,thereby generating more C^(2+).Even an observable three-phase interface on the porous fixed-bed can be regulated by adjusting the CO_(2)supply,for which the optimal gas inlet rate is 5-10 sccm.

关键词： Photocatalytic CO_(2)reduction Cu/Cd_(0.5)Zn_(0.5)S Porous fixed-bed Three-phase interface C^(2+)chemical fuel

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Spatio-Temporal flow Field Prediction of Turbulent Boundary Layer Based on PINN

Spatio-Temporal Flow Field Prediction of Turbulent Boundary ...

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Vortex Workshop on New Progress in Vortex Identification and Applications, VW 2023

作者： Zhu, Jiahao Song, Yang Dong, Xiangrui School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai200093 China

ISBN: (纸本)9789819786077

Based on the PINN neural network for the study of turbulence, it can solve the nonlinear equations without grid, which is different from the CFD method. This paper mainly uses the PINN method to study the temporal and spatial prediction of the turbulent boundary layer flow field, and in the absence of label values, based on the known flow field information, the unknown information is reasonably predicted by solving the N-S equation. The comparison of PINN prediction results with numerical simulation and experimental results verifies the feasibility of applying PINN to the study of turbulent boundary layer. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Computational fluid dynamics

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Experimental Investigation on Hydrophobic Behavior of Carbon Spheres Coated Surface Made from Microplastics

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Journal of Renewable Materials 2021年第12期9卷 2159-2174页

作者： Peng Liu Bin Bai Cui Wang Yunan Chen Zhiwei Ge Wenwen Wei Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

In this paper,a simple method to plate a hydrophobic coating on the inner surface of a small-scaled tube was proposed,where the coating consisted of carbon *** common plastics polystyrene,polycarbonate and polyethylene were used as the feedstocks to be processed in supercritical water in a quartz tubular *** reaction,the contact angle of droplet on the inner surface of the quartz tube was turned out to be over 100°,significantly larger than that of the blank tube 54°.When processing polystyrene in the 750℃ supercritical water for 10 min,the largest contact angle was obtained,up to 145°.Besides,in this sample,the size of carbon spheres was smallest,about 2.09μm diameter on *** comparing among different types of plastics under the same condition,the contact angle of surface made from PC took the dominant position over that of PS and PE,124°,100°and 90°,*** the sample made from PC,carbon spheres adhered into a mountainlike shape,producing a binary geometric ***,this research could be helpful in the discussion of plastic waste management and carbon spheres fabrication with low cost.

关键词： Plastic wastes hydrothermal method carbon spheres supercritical water hydrophobicity

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