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Numerical study on heat transfer of two-phase fluid in helical coil pipe under ocean condition

APPLIED THERMAL ENGINEERING 2025年 258卷

作者： Xu, Xinyan yu, shuwen Peng, Changhong Univ Sci & Technol China Sch Nucl Sci & Technol 96 Jinzhai Rd Hefei 230026 Peoples R China

The thermal hydraulic characteristics and heat transfer of two-phase fluid in helical coil once-through steam generator under ocean conditions like rolling and heaving motions are studied numerically. A CFD model is established to analyze the effects of motion parameters like amplitude, period and rolling radius and the heat flux distribution are discussed. The analysis shows that the overall heat transfer decreases under ocean conditions, but the overall deterioration is limited, indicting the helical coil pipe has the stability for ocean conditions. The additional forces like Coriolis, centrifugal and inertial forces introduced by rolling motion are analyzed theoretically and the result shows it detorts the original two main vortexes responsible for high heat transfer due to its spiral geometry, making heat transfer fluctuates up and down periodically near the steady state value. As rolling height increases, the heat transfer is nonlinear due to the competition between Coriolis force and centrifugal and inertial forces. As rolling amplitude increases, the heat transfer variation increases and the local heat transfer deterioration is severely aggravated, indicating high rolling amplitude should be avoided as possible. Increasing rolling period makes heat transfer behavior more approximate to static case as gravity and centrifugal force due to spiral geometry is dominate. Under heaving motion, the overall heat transfer decreases, and increasing heaving amplitude and decreasing period make the fluctuation more severe.

关键词： Ocean condition Helical coil pipe Heat transfer Numerical simulation

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Numerical study on transient critical heat flux prediction with dynamic bubble simulation under exponentially escalating heat input

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ENERGY 2025年 323卷

作者： Xu, Xinyan yu, shuwen Peng, Changhong Univ Sci & Technol China Sch Nucl Sci & Technol 96 Jinzhai Rd Hefei 230026 Peoples R China Nucl Power Inst China Natl Key Lab Nucl Reactor Technol Chengdu Peoples R China

This paper presents the development and validation of numerical transient critical heat flux (CHF) prediction model based on the coupling of dynamic bubble simulation by Monte Carlo (MC) method and two-dimensional heat conduction model of the substrate by finite volume method. The model aims to predict the transient CHF value, estimate the dynamic heat flux and temperature distribution and evaluate various phenomena of bubble behaviors during transient boiling heat transfer process under exponentially escalating heat power input. The dynamic bubble simulation is performed by modeling and tracking bubble nucleation, bubble growth, bubble departure and bubble coalescence procedures of individual bubbles in real time based on simplified fundamental bubble parameters including nucleation site density (NSD), bubble departure diameter, bubble growth and waiting time. The heat flux partitioning model was used to evaluate different heat fluxes based on the classification of microlayer and dry spot regions. According to the dynamic heat flux boundary due to dynamic bubble behavior and exponentially escalating heat input, the thermal conductivity model was coupled to feed back the wall temperature distribution for further updates and simulation of dynamic bubble behavior. Numerical simulation results showed good agreement with transient flow boiling experimental results with escalating periods ranging from 500 ms to 5 ms, and the results showed the trend that the transient CHF value increases with decreasing escalating period as observed in experiments. Sensitivity analysis of input bubble parameters was performed and showed that the model is more sensitive to bubble departure diameter and bubble waiting time.

关键词： Transient CHF Transient boiling heat transfer Exponentially escalating period Dynamic bubble simulation Model coupling

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Interfacial analysis and development of condensation models with OpenFOAM

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2024年 202卷

作者： yu, shuwen Cheng, Ning Peng, Changhong Univ Sci & Technol China Sch Nucl Sci & Technol 96 Jinzhai Rd Hefei 230026 Peoples R China China Ship Dev & Design Ctr 268 Zhangzhidong Rd Wuhan 430060 Peoples R China

Interfacial mass and heat transfer are crucial factors in phase-change models. In this study, based on the open source toolbox OpenFOAM, an extended volume-of-fluid (VOF) solver with phase transition inserted is utilized to study three typical phase-change models (Lee model, energy balance model, and Rattner model). Through simulations and analysis of phase-change problems, we found that these three models exhibit different sensitivities to gas thermal conductivity, particularly through the interfacial heat conduction equation. The temperature and heat source distributions at the vapor-liquid interface in each model were analyzed using analytical problems, such as the one-dimensional Stefan problem and the Nusselt film condensation problem. Based on the analysis, we proposed a new energy balance model that considers the ratio of vapor-liquid thermal conductivity to correct the impact of vapor thermal conductivity. Furthermore, we introduced a temperature correction term to stabilize the interfacial temperature at the saturation temperature. The simulation results of the proposed model demonstrated excellent agreement with the analytical solutions of quasi-static condensation processes, including the one-dimensional Stefan problem and the Nusselt film condensation problem. Throughout the dynamic condensation process with rising bubbles, different phase-change models exhibited significant differences in condensing power distribution over space and time.

关键词： Condensation model Stefan problem Nusselt film condensation Bubble condensation

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MVEA: Multi-View Graph Convolutional Networks for Entity Alignment in Cross-lingual Knowledge Graphs 24

MVEA: Multi-View Graph Convolutional Networks for Entity Ali...

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13th International Conference on Computing and Pattern Recognition, ICCPR 2024

作者： yu, shuwen Wang, Yongli Nanjing University of Science and Technology Nanjing Jiangsu China

ISBN: (纸本)9798400717482

Cross-lingual Entity Alignment (EA) aims to identify whether different entities in two Knowledge Graphs (KGs) constructed in various languages refer to the same real-world object. Current approaches predominantly focus on the structure aspect to address the heterogeneity between different KGs, however, they often overlook the semantic information of relations. Some methods attempt to incorporate attribute information to alleviate the sparsity issue present in some KGs. Nevertheless, these approaches fail to account for the dynamic nature of entities that are influenced by time, treating the attributes of entities and their relations as static. In fact, knowledge networks in the real world evolve over time, with dynamic changes in attributes and relations across different time periods. To fully exploit the rich information embedded in cross-lingual KGs, we propose Multi-View Graph Convolutional Networks for Entity Alignment (MVEA) which comprehensively consider entity representations from static relation and attribute views, as well as a dynamic time view. We then aggregate similarity matrices from both the static joint view and the dynamic time view for alignment learning. Our model has been tested on widely-used cross-lingual EA datasets and sparser datasets, demonstrating its superiority. © 2024 Copyright held by the owner/author(s).

关键词： Knowledge graph

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Gelation, self-assembly, and acid responsive properties of an unsymmetrical 1,3,4-oxadiazole derivative

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SOFT MATERIALS 2024年第2期22卷 129-138页

作者： Hu, Xueqing Zhang, Qing yu, shuwen Wang, Guizhi Zhang, Tianren Suzhou Univ Sch Chem & Chem Engn Anhui Key Lab Spin Electron & Nanomat Suzhou Anhui Peoples R China Xuzhou Med Univ Affiliated Huaihai Hosp Dept Nephrol Xuzhou Jiangsu Peoples R China Jilin Univ Coll Mat Sci & Engn Key Lab Automobile Mat Minist Educ Changchun Peoples R China Suzhou Univ Sch Chem & Chem Engn Anhui Key Lab Spin Electron & Nanomat Suzhou 234000 Peoples R China

A novel unsymmetrical 1,3,4-oxadiazole derivative (2-POXD-B8) was synthesized. 2-POXD-B8 can form organogel in methanol. The gelation and self-assembly behavior of 2-POXD-B8 were researched by SEM, XRD, UV-vis, and temperature-dependent FT-IR, etc. pi-pi interaction and van der Waals force are viewed as the main driving forces in the self-assembly process. In addition, 2-POXD-B8 showed acid-responsive properties in different states, including gel state and film state. A dual-channel acid response by reversible solution-gel transition and fluorescence changes was observed in the methanol gel system. The protonation of 2-POXD-B8 is the reason for its acid-responsive property.

关键词： 1,3,4-oxadiazole organogel self-assembly acid responsive

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Novel Sc-doped Bi_(3)TiNbO_(9) ferroelectric nanofibers prepared by electrospinning for visible-light photocatalysis

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Journal of Rare Earths 2023年第3期41卷 365-373,I0002页

作者： Zhixiong Song shuwen yu Kaixian Wang Zhengming Jiang Liyan Xue Fan Yang Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350002China Xiamen Institute of Rare Earth Materials Haixi InstituteChinese Academy of SciencesXiamen 361021China CAS Key Laboratory of Design and Assembly of Functional Nanostructures Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Chinese Academy of SciencesXiamen 361021China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341001China

In this work,a novel Sc-doped Bi_(3)TiNbO_(9) ferroelectric nanofiber was first prepared by *** nanofibers are approximately 100 nm level in *** photocatalytic activity analysis reveals that the Bi_(3)TiNbO_(9) nanofibers synthesized by electrospinning are superior to powders prepared by the solid-state method,which is mainly attributed to the high specific surface area and high surface activity of the *** addition,doping Sc can reduce the band gap of Bi_(3)TiNbO_(9) and further improve the photocatalytic ***_(3)TiNbO_(9) nanofibers containing 5 mol%Sc have the highest photocatalytic activity,which can degrade 98.55%of RhB under 405 nm light irradiation for 120 *** addition,the catalytic mechanism of the catalyst was obtained by scavenger tests,active species capture tests and band structure *** three cycles of photocatalytic experiment,the degradation rate is decreased by only 2.42%,proving that the nanofibers catalyst has excellent *** work provides good prospects for the practical application of electrospinning technology in the field of photocatalysis.

关键词： Nanofibers Ferroelectric Scandium Visible-light photocatalysis Rare earths

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Recent advances in the interfacial engineering of MOF-based mixed matrix membranes for gas separation

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NANOSCALE 2024年第16期16卷 7716-7733页

作者： yu, shuwen Li, Conger Zhao, Shuke Chai, Milton Hou, Jingwei Lin, Rijia Suzhou Univ Sch Chem & Chem Engn Suzhou 234000 Peoples R China Univ Queensland Sch Chem Engn St Lucia Qld 4072 Australia Shanghai Tech Univ Sch Phys Sci & Technol Shanghai 201210 Peoples R China

The membrane process stands as a promising and transformative technology for efficient gas separation due to its high energy efficiency, operational simplicity, low environmental impact, and easy up-and-down scaling. Metal-organic framework (MOF)-polymer mixed matrix membranes (MMMs) combine MOFs' superior gas-separation performance with polymers' processing versatility, offering the opportunity to address the limitations of pure polymer or inorganic membranes for large-scale integration. However, the incompatibility between the rigid MOFs and flexible polymer chains poses a challenge in MOF MMM fabrication, which can cause issues such as MOF agglomeration, sedimentation, and interfacial defects, substantially weakening membrane separation efficiency and mechanical properties, particularly gas separation. This review focuses on engineering MMMs' interfaces, detailing recent strategies for reducing interfacial defects, improving MOF dispersion, and enhancing MOF loading. Advanced characterisation techniques for understanding membrane properties, specifically the MOF-polymer interface, are outlined. Lastly, it explores the remaining challenges in MMM research and outlines potential future research directions. This is a comprehensive review for resolving compatibility challenges in fabricating practical metal-organic framework composite membranes for gas separation.

关键词： Defects

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An Explainable Deep Learning Model for Daily Sea Ice Concentration Forecast

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2024年 62卷 1页

作者： Li, Yang Qiu, yubao Jia, Guoqiang yu, shuwen Zhang, Yixiao Huang, Lin Lepparanta, Matti Chinese Acad Sci Aerosp Informat Res Inst Key Lab Digital Earth Sci Beijing 100094 Peoples R China Int Res Ctr Big Data Sustainable Dev Goals Beijing 100094 Peoples R China Univ Chinese Acad Sci Coll Resources & Environm Beijing 100049 Peoples R China Univ Helsinki Inst Atmospher & Earth Sci Helsinki 00014 Finland

As Arctic sea ice rapidly declines, accurate daily sea ice concentration (SIC) forecasts become crucial for Arctic research and operations. Emerging deep learning (DL) forecast models have the advantage of consuming fewer computational resources compared with numerical forecast systems. However, DL forecast models face challenges of lacking sea ice domain knowledge, low forecast accuracy in the marginal ice zone (MIZ), and poor explainability. This study proposes an explainable DL model, SIFNet, for daily Arctic SIC forecasts, which considers the domain knowledge of teleconnections and lagged correlations by integrating the convolutional block attention module (CBAM) and temporal feature convolution module (TFCM). To improve SIFNet's accuracy in the MIZ, an MIZ-weighted loss function is used for fine-tuning, leading to a notable 1.36% reduction in the mean absolute error (MAE) of MIZ forecasts (MIZ MAE). In the January 2020-December 2023 test scenario, forecasting SIC for the future 49 days using the past 21 days' data, SIFNet demonstrates forecast accuracies with the MAE of 4.69%, binary accuracy (BACC) of 95.16%, structural similarity index (SSIM) of 95.13%, and MIZ MAE of 18.22%. Compared with the other two DL models and nine numerical forecast systems, SIFNet's forecasts achieve higher accuracies. Using layerwise relevance propagation (LRP) technique, the LRP- $\vert z\vert $ rule is constructed to improve SIFNet's explainability. During Arctic minimum sea ice extent (SIE) periods, SIFNet forecasts confirm upward and downward surface solar radiation as predictors for minimum SIE. Similarly, over the past 30 years, precipitation phase is considered a potentially significant factor influencing SIC forecasts.

关键词： Arctic deep learning (DL) explainability marginal ice zone (MIZ) sea ice concentration (SIC) forecast

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Analysis of Spatiotemporal Characteristics of Taxi Traffic Violations 24

Analysis of Spatiotemporal Characteristics of Taxi Traffic V...

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24th COTA International Conference of Transportation Professionals: Resilient, Intelligent, Connected, and Lowcarbon Multimodal Transportation, CICTP 2024

作者： Yan, Lixin yu, shuwen Li, Huangchengcheng Wu, Qian School of Transportation Engineering East China JiaoTong Univ. Nanchang China Jiangxi Provincial Communications Investment Group Co. Ltd. Nanchang China

ISBN: (数字)9780784485484

ISBN: (纸本)9780784485484

Traffic violations are a significant factor contributing to road traffic accidents. Taxis are a crucial component of urban traffic. Studying taxi traffic violations is helpful to reduce the occurrence of urban road traffic violation events. In order to study the spatiotemporal characteristics of taxi violations, an empirical analysis was conducted using the raw data of 43,622 taxi traffic violations from July 2020 to June 2021 in Nanchang City. The ArcGIS kernel density analysis tool was employed to visually analyze spatiotemporal characteristics of taxi traffic violations. The results show that taxis were more likely to commit traffic violations near hospitals, schools, and intersections. The highest incidence of serious violations is concentrated in the afternoon and before dawn. The conclusion of this study can provide insightful suggestions for the traffic enforcement department to adjust the patrol plans according to the periods. © ASCE.

关键词： Roads and streets

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A Little Alkali Solution Triggering a Qualitative Change of PEEK-Based Composites From Brake-Like Materials Into Self-Lubricating Ones

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JOURNAL OF APPLIED POLYMER SCIENCE 2025年

作者： Zhang, Ligang Wang, Yan yu, shuwen Zhang, Pinghua Su, Yongxiang Liu, Weikang Suzhou Univ Sch Chem & Chem Engn Key Lab Spin Electron & Nanomat Anhui Higher Educ Inst Suzhou Peoples R China Chinese Acad Sci Lanzhou Inst Chem Phys State Key Lab Solid Lubricat Lanzhou Peoples R China Qingdao Port Dongjiakou Ore Terminal Co LTD Qingdao Peoples R China

A series of silica (SiO2) microspheres filled poly-ether-ether-ketone (PEEK) composites were prepared by hot-pressing, and their tribological performance when sliding against stainless steel was studied by drop-lubricated with sodium hydroxide (NaOH) solution compared with deionized (DI) water. Interfacial chemical reactions were mainly investigated, and the microtopography, chemical structures, and compositions of the worn surfaces of the tribo-pairs were also systematically characterized. The results showed that compared with DI water, 2 mol/L NaOH solution played a significant role in improving the wear resistance of 30 wt% SiO2 microspheres filled PEEK and can reduce the wear rate by 79%. COF was reduced from 0.45 to 0.12, the lubricity improving by 73%. In comparison to neat PEEK, the wear resistance of the above composite can enhance by one order of magnitude, and COF can reduce by 45%. This work provides powerful evidence for the direct positive impact of interfacial chemical reactions on the tribological behaviors.

关键词： friction functionalization of polymers surfaces and interfaces synthesis and processing techniques wear and lubrication

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