检索结果-南通市图书馆

Numerical study on two-phase flow in horizontal pipe

在线全文

学校读者我要写书评

暂无评论

排灌机械工程学报 2021年第4期39卷 379-385,425页

作者： WU Yuting XU Kewei KIM Hyoungbum School of Mechanical and Aerospace Engineering Gyeongsang National UniversityJinju 52828S.Korea Research Center for Aircraft Parts Technology Gyeongsang National UniversityJinju 52828S.Korea

Two-phase flow in a horizontal pipe was investigated by using numerical and experimental visualization methods.A horizontal pipe was built for qualitative and quantitative flow visualization.The length of horizontal pipe flow system was 9.5 m and the inner diameter was 51 mm.High-speed video method was used for the qualitative visualization and PIV method was applied for the quantitative visua-lization.The same geometry model was used for the numerical study.Three flow regimes including stratified flow,elongated bubble and slug flow field were generated and visualized by using numerical and experimental methods.The results show that the numerical simulation results are qualitatively si-milar to that of the experimental results.In addition,more quantitative results can be analyzed by numerical method.Development and decay process of slug flow was investigated,showing that the decay of slug heavily depends on the magnitude of nose velocity and its lasting time.It can also be found that the liquid superficial velocity plays a significant role in affecting the slug frequency.When keeping the gas superficial velocity constant,the frequency will increase with the liquid superficial velocity.

关键词： two-phase flow CFD PIV slug flow slug frequency

Numerical Analysis on Charging Performance of the Macro-Encapsulating Combined Sensible-Latent Heat Storage System with Structural Parameters

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第3期33卷 1026-1036页

作者： WANG Wei PAN Zhenfei WANG Jingfu WU Yuting MA Chongfang Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of EducationCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China Key Laboratory of Heat Transfer and Energy Conversion Beijing MunicipalityCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China

For combined sensible-latent heat storage system(CSLHS)(termed as the hybrid configuration),macro encapsulation can effectively solve the leakage problem of PCMs.However,due to the poor thermal conductivity of PCMs,the charging performance of the hybrid configuration slightly increases compared to the solid structure(with only sensible materials).Meanwhile,the natural convection in the PCMs zone could improve the charging performance.So,how to improve natural convection intensity is a key issue for the CSLHS by macro encapsulating.It is found that adding fins can significantly enhance natural convection and accelerate the melting of PCM.In this paper,we proposed the hybrid configuration with fins built-in by macro encapsulation,and analyzed its charging performance with different fin structural parameters in the PCM zone by CFD simulation.In the case,the sensible heat storage material is high-temperature concrete and the PCM is a low-melting-point mixed molten salt.We analyzed the effects of fin number,fin length and fin thickness on the charging performance of the hybrid configuration respectively.From the result,the charging performance increases with the fin number,but the increase rate gradually decreases.When the fin number is 6,the charging performance increases by 20.18%compared to the situation without fin.The charging performance increases gradually with the fin length.Compared with the hybrid configuration without fin,for each 10 mm increase in fin length,its charging performances increase by 4.09%,5.26%,7.02%,8.77%,11.70%,and 15.79%,respectively.Different from number and length of fins,the effect of thickness on the charging performance is very small.When the fin thickness increased from 1 mm to 4 mm,the charging performance only increased by 2.3%.It indicates that the main reason for the improving the charging performance is to increase the natural convection intensity by dividing the PCM zone through fins.These results show that the charging performance of the CSLHS with macro encapsulation can be im

关键词： macro-encapsulation hybrid configuration natural convection structural parameter charging performance

The Processes-Based Attributes of Four Major Surface Melting Events over the Antarctic Ross Ice Shelf

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2023年第9期40卷 1662-1670页

作者： Wenyi LI yuting wu Xiaoming HU School of Atmospheric Sciences Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China Chongqing Research Institute of Big Data Peking UniversityChongqing 401333China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies Sun Yat-sen UniversityZhuhai 519000China

The Ross-Amundsen sector is experiencing an accelerating warming trend and a more intensive advective influx of marine air streams.As a result,massive surface melting events of the ice shelf are occurring more frequently,which puts the West Antarctica Ice Sheet at greater risk of degradation.This study shows the connection between surface melting and the prominent intrusion of warm and humid air flows from lower latitudes.By applying the Climate Feedback-Response Analysis Method(CFRAM),the temporal surge of the downward longwave(LW)fluxes over the surface of the Ross Ice Shelf(RIS)and adjacent regions are identified for four historically massive RIS surface melting events.The melting events are decomposed to identify which physical mechanisms are the main contributors.We found that intrusions of warm and humid airflow from lower latitudes are conducive to warm air temperature and water vapor anomalies,as well as cloud development.These changes exert a combined impact on the abnormal enhancement of the downward LW surface radiative fluxes,significantly contributing to surface warming and the resultant massive melting of ice.

关键词： Ross Ice Shelf(RIS) surface melting warm and humid air advection downward longwave radiation Climate Feedback-Response Analysis Method(CFRAM)

Flow Characteristics of a Refrigerant-Oil Mixture in a Vapor Compression Heat Pump Heat Exchanger for Space Applications

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第2期31卷 407-416页

作者： MA Rui YE Yilin MA Xudong WU Yuting YAN Suying WANG Feng College of Energy and Power Engineering Inner Mongolia University of TechnologyHohhot 010051China Key Laboratory of Wind and Solar Energy Utilization Mechanism and Optimization in Inner Mongolia Inner Mongolia University of TechnologyHohhot 010051China Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of EducationBeijing 100124China

The vapor compression heat pump is considered as the best option for aerospace thermal control system.The heat exchanger in vapor compression heat pump is a component that is greatly influenced by the cosmic environment.Lubricating oil enters heat pump system with a refrigerant under microgravity,and the entrance of the lubricant increases the complexity of the flow.In this work,FLUENT software was used to study the flow and lubricant deposition of a two-phase mixture of lubricant POE RL 68H and refrigerant R134a in a heat exchanger without the consideration of phase-change heat transfer.The functional relationships between the oil film thickness and the proportion of lubricating oil,the gravitational acceleration,the inlet flow velocity,and the placement directions of the two phases of oil in the heat exchanger were established.The results demonstrate that with the increase of the gravitational acceleration and the lubricating oil content,the thickness of the oil film will exhibit an S-type change in line with the Boltzmann function,and the amount of lubricating oil deposition will increase.With the increase of the flow velocity,the thickness of the oil film will exhibit an exponential decline.

关键词： heat exchanger two-phase flow microgravity numerical simulation vapor compression heat pump

Numerical Simulation of Charging Performance of Combined Sensible-Latent Heat Storage System with a Macro-Encapsulation Method

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2023年第6期32卷 2008-2017页

作者： WANG Wei PAN Zhenfei LEI Biao WU Yuting WANG Jingfu MA Chongfang Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of EducationCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China Key Laboratory of Heat Transfer and Energy Conversion Beijing MunicipalityCollege of Energy and Power EngineeringBeijing University of TechnologyBeijing100124China

In recent years,heat storage system combining sensible and latent heat materials has received more and more attentions.In this paper,we proposed the hybrid configuration with a macro-encapsulation,and analyzed its charging performance with different influencing factors by CFD simulation.In the case,the sensible heat storage materials are magnesia brick or HT concrete and the phase change materials(PCMs)are mixed molten salts.Firstly,we analyzed the heat transfer characteristics of the hybrid configuration in charging process.Then,we analyzed the effect of heating power on charging performance.The maximum temperature of the heating surface shall not exceed 500℃as the constraint condition,the heat storage capacity increases at first and then decreases with the heating power.Then,we compared the charging performance of different solid structure and the hybrid configurations.Whether magnesia brick or HT concrete,the charging performance of the solid structure is better than that of the hybrid configuration,because the thermal conductivity of the molten salt is significantly lower than that of the two sensible heat storage materials.Then,we compared the charging performance of different molten salts.The hybrid configuration with lower melting point molten salt has better performance because of more intensity natural convection.Finally,we analyzed the charging performance of the hybrid configuration used the composite phase change material(CPCM)with high thermal conductivity and specific heat.From the result,the charging performance increases by 22.5%compared with the solid structure.These results indicate that the hybrid configuration with the macro-encapsulation method is a potential form of thermal energy storage,but it needs to be further optimized.

关键词： thermal energy storage hybrid configuration natural convection thermophysical property charging performance

Flexible Operation Mode of Coal-fired Power Unit Coupling with Heat Storage of Extracted Reheat Steam

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第2期31卷 436-447页

作者： WEI Haijiao LU Yuanwei YANG Yanchun ZHANG Cancan WU Yuting LI Weidong ZHAO Dongming MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation Beijing Key Laboratory of Heat Transfer and Energy ConversionFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China China Huaneng Group Clean Energy Research Institute Co.Ltd Beijing 102209China

In order to provide more grid space for the renewable energy power,the traditional coal-fired power unit should be operated flexibility,especially achieved the deep peak shaving capacity.In this paper,a new scheme using the reheat steam extraction is proposed to further reduce the load far below 50%rated power.Two flexible operation modes of increasing power output mode and reducing fuel mode are proposed in heat discharging process.A 600 MW coal-fired power unit with 50%rated power is chosen as the research model.The results show that the power output is decreased from 300.03 MW to 210.07 MW when the extracted reheat steam flow rate is 270.70 t·h^(-1),which increases the deep peak shaving capacity by 15%rated power.The deep peak shaving time and the thermal efficiency are 7.63 h·d^(-1)and 36.91%respectively for the increasing power output mode,and they are 7.24 h·d^(-1)and 36.58%respectively for the reducing fuel mode.The increasing power output mode has the advantages of higher deep peak shaving time and the thermal efficiency,which is recommended as the preferred scheme for the flexible operation of the coal-fired power unit.

关键词： coal-fired power unit flexible operation deep peak shaving extracted reheat steam heat storage

Flexible strain sensors fabricated using aligned carbon nanofiber membranes with cross-stacked structure for extensive applications

在线全文

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2022年第3期13卷 432-446页

作者： Tao Yan yuting wu Jian Tang Zhijuan Pan College of Textile and Clothing Engineering Soochow UniversitySuzhouP.R.China National Engineering Laboratory for Modern Silk SuzhouP.R.China

Carbon nanofibers(CNFs)with excellent conductivity and stability have become a promising material to design the strain sensing network.To date,however,the effect of the stacked structure of CNF membrane on the sensing performance has rarely been stu-died.In this work,we reported a high-performance sensor based on the cross-stacked aligned CNF membrane.The effects of crossstacked structures on the sensing characteristics were systemati-cally investigated.The flexible strain sensor could capture low detection limit(0.998),excellent durability and quick response time(<200 ms)were demonstrated.The excellent com-prehensive performances were simultaneously obtained.The sen-sor could be used in extensive applications,such as monitoring body movements and distinguishing the track of writing.

关键词： Electrospinning carbon nanofiber membrane crossstacked structure strain sensor extensive applications

Fabricating a smart clothing system based on strain-sensing yarn and novel stitching technology for health monitoring

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第2期67卷 587-596页

作者： TANG Jian WU Yuting MA ShiDong ZHANG YuMin XU RuoJie YAN Tao PAN ZhiJuan College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123China National Engineering Laboratory for Modern Silk Suzhou 215123China

Various yarn-shaped flexible strain sensors have recently been developed.However,research is lacking on additive manufacturing for smart clothing for integrating yarn sensors with commercial garments.Herein,a strain-sensing yarn is sewn into a piece of fabric through a novel stitching technique,and the influence of the stitching method and needle pitch on the sensing performance is investigated using finite element analysis(FEA).The sensing performance could be improved when the sensing yarn is self-locked in the fabric at the needle eyes,and the needle pitch was reduced to 0.5 cm,which is attributed to the enhanced stress and strain concentration.Meanwhile,the composite sensing fabric featured outstanding performance,including a low detection limit(0.1%),rapid response(280 ms),excellent durability(10000 cycles),and high stability(negligible drift and frequency independence).In addition,the remarkable wear resistance,washability,and anti-interference to ambient humidity and perspiration were obtained.Therein,the optimal stitch trace lengths of sensing yarn for detecting elbow motion,breathing,and heartbeats are discussed.Finally,a smart clothing system composed of smart clothing,data acquisition unit,and mobile APP was developed to simultaneously detect human movement and physiological signals.This work provides a reference to produce intelligent garments based on yarn sensors for health monitoring.

关键词： strain-sensing yarn composite sensing fabric smart clothing system stitching technology health monitoring

Integrating Manifold Knowledge for Global Entity Linking with Heterogeneous Graphs

在线全文

学校读者我要写书评

暂无评论

Data Intelligence 2022年第1期4卷 20-40页

作者： Zhibin Chen yuting wu Yansong Feng Dongyan Zhao Wangxuan Institute of Computer Technology Peking UniversityBeijing 100871China Center for Data Science Peking UniversityBeijing 100871China The MOE Key Laboratory of Computational Linguistics Peking UniversityBeijing 100871China

Entity Linking(EL)aims to automatically link the mentions in unstructured documents to corresponding entities in a knowledge base(KB),which has recently been dominated by global models.Although many global EL methods attempt to model the topical coherence among all linked entities,most of them failed in exploiting the correlations among manifold knowledge helpful for linking,such as the semantics of mentions and their candidates,the neighborhood information of candidate entities in KB and the fine-grained type information of entities.As we will show in the paper,interactions among these types of information are very useful for better characterizing the topic features of entities and more accurately estimating the topical coherence among all the referred entities within the same document.In this paper,we present a novel HEterogeneous Graph-based Entity Linker(HEGEL)for global entity linking,which builds an informative heterogeneous graph for every document to collect various linking clues.Then HEGEL utilizes a novel heterogeneous graph neural network(HGNN)to integrate the different types of manifold information and model the interactions among them.Experiments on the standard benchmark datasets demonstrate that HEGEL can well capture the global coherence and outperforms the prior state-of-the-art EL methods.

关键词： Entity linking Heterogeneous graph Graph neural network Entity disambiguation Knowledge base