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Thermal Conductivity and Heat Transfer Coefficient of Concrete

作者： Xinran Li Xuan Xu Jia Li Ximei Liu north china electric power university

Based on literature, questionnaires and interviews, this survey analyzes the awareness of green energy, energy saving and emission reduction and its application status and problems in north china electric power university, and compares them with other universities in the region. Based on the advanced experience both domestically and internationally, from the management, technology, culture and talent level, this paper aims to propose countermeasures and suggestions for the green energy-saving development of this university, construct strategic organization management system and incentive mechanism, enhance the awareness of green energy conservation and campus culture, promote the introduction of advanced green energy-saving technologies and talents, and enhance the spillover effect of green technology on society and the role of radiation to create a model green energy-saving college brand.

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Journal of Wuhan university of Technology(Materials Science) 2011年第4期26卷 791-796页

作者：郭利霞 north china university of water resources and electric power

A very simple model for predicting thermal conductivity based on its definiensis was presented. The thermal conductivity obtained using the model provided a good coincidence to the investigations performed by other authors. The heat transfer coefficient was determined by inverse analysis using the temperature measurements. From experimental results, it is noted that heat transfer coefficient increases with the increase of wind velocity and relative humidity, a prediction equation on heat transfer coefficient about wind velocity and relative humidity is given.

关键词： thermal conductivity heat transfer coefficient relative humidity wind velocity

Numerical study on falling film flowing characteristics of R113 inside vertical tube under different structural conditions

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Chinese Journal of Chemical Engineering 2020年第1期28卷 23-32页

作者： Weishu Wang Yihan Liao Youzhi Yan Bingchao Zhao Tao Wang Shanshan Shangguan north china university of water resources and electric power Zhengzhou 450045China

To develop an appropriate falling film evaporation device for organic fluid cogeneration, a numerical study on the gas–liquid two-phase counter-current flow characteristics of R113 inside a vertical tube under different structural conditions was conducted using the Fluent software. The effects of the tube length, tube diameter, and annular gap on the falling film flow characteristics were determined, respectively. The results indicated that under a certain spray density, the falling film thickness in the region of the steady section was almost constant with different structural parameters for the tube diameter, tube length, and annular gap. In addition, a smaller tube diameter resulted in a steadier film flow. When the tube diameter decreased to a specific value, the film thickness showed a uniform distribution along the wall surface. This indicated that a best falling tube diameter exists. Meanwhile, the film fluctuation was enhanced with an increase in the tube length. When the tube length was greater than 1.2 m, the falling film splashed and could not completely wet the wall surface. The film fluctuation was enhanced by decreasing the annular gap, and the film could not be formed when the annular gap was smaller than 1.2 mm.

关键词： Falling film Numerical simulation R113

Lithium ion batteries cathode material: V_(2)O_(5)

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Chinese Physics B 2022年第3期31卷 84-95页

作者： Baohe Yuan Xiang Yuan Binger Zhang Zheng An Shijun Luo Lulu Chen north china university of water resources and electric power Zhengzhou 450011China

Among all the known electrode materials, vanadium pentoxide(V_(2)O_(5)) has high reversible capacity. It is a very valuable material for research of the complexity, rich structure and morphology. However, it also has some disadvantages,such as poor cycle stability, low discharge voltage, low conductivity and Li^(+) diffusion coefficient. In this regard, researchers have carried out a lot of research, such as using various methods to improve the nanostructures, introducing heterostructures,introducing point defects or cation doping in the crystal structure, etc. The electrochemical performance of V_(2)O_(5)has been significantly improved in reversible capacity, high-rate capacity and long-term cycle stability. In this paper, V_(2)O_(5)based nanostructure with different chemical composition are briefly introduced, and it covers V_(2)O_(5)nanomaterials with different morphology, including 1D nanorods, nanobelts, nanotubes, 2D leaf like nanosheets and other nanosheets, and 3D hollow structures, porous nanostructures, porous eggshell microsphere structures. The composite nanomaterials of V_(2)O_(5)and different carbonaceous supports are also introduced. Finally, the V_(2)O_(5)composite materials doped with cations are discussed. The electrochemical performance of V_(2)O_(5)based electrode can be improved effectively by obtaining appropriate nanostructure and optimized chemical composition.

关键词： lithium ion battery V_(2)O_(5)nanostructures electrochemical properties nanotubes and nanowires

Runoff change in the Yellow River Basin of china from 1960 to 2020 and its driving factors

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Journal of Arid Land 2024年第2期16卷 168-194页

作者： WANG Baoliang WANG Hongxiang JIAO Xuyang HUANG Lintong CHEN Hao GUO Wenxian School of water Conservancy North China University of Water Resources and Electric PowerZhengzhou 450046China College of water resources North China University of Water Resources and Electric PowerZhengzhou 450046China

Analysing runoff changes and how these are affected by climate change and human activities is deemed crucial to elucidate the ecological and hydrological response mechanisms of *** Indicators of Hydrologic Alteration and the Range of Variability Approach(IHA-RVA)method,as well as the ecological indicator method,were employed to quantitatively assess the degree of hydrologic change and ecological response processes in the Yellow River Basin from 1960 to *** Budyko's water heat coupling balance theory,the relative contributions of various driving factors(such as precipitation,potential evapotranspiration,and underlying surface)to runoff changes in the Yellow River Basin were quantitatively *** results show that the annual average runoff and precipitation in the Yellow River Basin had a downwards trend,whereas the potential evapotranspiration exhibited an upwards trend from 1960 to *** approximately 1985,it was reported that the hydrological regime of the main stream underwent an abrupt *** degree of hydrological change was observed to gradually increase from upstream to downstream,with a range of 34.00%-54.00%,all of which are moderate ***,significant differences have been noted among different ecological indicators,with a fluctuation index of 90.00%at the outlet of downstream hydrological stations,reaching a high level of *** the mutation,the biodiversity index of flow in the middle and lower reaches of the Yellow River was generally lower than that in the base *** research results also indicate that the driving factor for runoff changes in the upper reach of the Yellow River Basin is mainly precipitation,with a contribution rate of 39.31%-54.70%.Moreover,the driving factor for runoff changes in the middle and lower reaches is mainly human activities,having a contribution rate of 63.70%-84.37%.These results can serve as a basis to strengthen the protection and restoration efforts in the Yellow River Basin

关键词： Budyko theory hydrological regime attribution analysis ecological responses Yellow River climate change human activity runoff

Research on Modeling and Parameter Identification of Comprehensive Load Model of Distribution Network in Industrial Park

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Chinese Journal of Electronics 2024年第1期33卷 264-273页

作者： Tingling WANG Xiaohe YAN School of electric Engineering North China University of Water Resources and Electric Power Wenzhou Polytechnic

With the rapid development of industrial parks, its load model research has become a hot spot. In order to study the load of power system in industrial park, based on the characteristics of the industrial park load, a comprehensive load admittance static model with full voltage range adaptability is considered, and a comprehensive load model of distribution network of the industrial park is established. A complete parameter identification of the model is carried out through chaos particle swarm optimization. The simulation results show that the model can effectively describe the load characteristics of the distribution network in industrial parks.

关键词： Chaos Adaptation models Analytical models Parameter estimation Induction motors Simulation Distribution networks

Wind-Induced Vibration Control for Substation Frame on Viscous Damper

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Computers, Materials & Continua 2020年第3期62卷 1303-1315页

作者： Bingji Lan Kanghao Yan north china university of water resources and electric power Zhengzhou450045China

In order to study the wind-induced vibration control effect of the viscous damper on the large-scale substation frame,this paper takes the large-scale 1000 kV substation frame of western Inner Mongolia as an *** time-history sample of pulsating wind load is simulated by harmonic superposition method based on Matlab software.6 kinds of viscous damper arrangement schemes have been designed,and SAP2000 finite element software is used for fine modeling and input wind speed time history load for nonlinear time history *** displacement and acceleration of a typical node are the indicators of wind vibration *** wind-induced vibration control effects of different schemes under different damping parameters have compared,and the damping parameters are analyzed for the optimal layout *** results show that a viscous damper has installed in the lower layers of the substation;a viscous damper is placed between the ground column and the lattice *** is an integrated optimal *** wind-induced vibration control effect of the optimal scheme is sensitive to the viscous damper parameters,and the control effect does not increase linearly with the increase of the damping index and the damping *** to different damping indexes,the damping coefficient has a better range of values.

关键词： Viscous damper wind-induced vibration control arrangement plan damping coefficient damping index

Numerical Simulation and Optimization of Staged Combustion and NO_x Release Characteristics in Precalciner

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Journal of Thermal Science 2019年第5期28卷 1024-1034页

作者： WANG Weishu LIAO Yihan LIU Jun HUANG Zhihao TIAN Miao Thermal Engineering Research Centre North China University of Water Resources and Electric Power

In order to study the combustion characteristics in a precalciner, the temperature and composition field in a typical Trinal-sprayed calciner were numerically analysed. The results obtained by simulation were compared to actual measurements and the simulated results were in good agreement with the measured ones. The results indicated that the aerodynamic flow field in the precalciner is satisfactory, and a symmetrical reflux occurs in the shrinkage zone of the precalciner because of air staging, which can increase the residence time of the solid particles. The temperature distribution in the furnace is uniform, and the average temperature is greater than 1200 K, which can satisfy the conditions for the pulverised coal combustion and raw material decomposition. The mass fraction distribution of oxygen, carbon monoxide, and carbon dioxide in the precalciner is closely related to the temperature distribution. The concentration of nitrogen oxides(NO_x) exhibits a trend of increasing, decreasing and then increasing, and finally tending to a stable level. Within a certain velocity range, the average temperature in the precalciner and the decomposition efficiency of the raw material increase as the flue gas velocity increases. When the flue gas velocity is 24 m/s, the overall performance of the precalciner is optimal.

关键词： TTF precalciner staged combustion NOx emission characteristics optimization

A Conscientious Investigation into the Effect of Re and Mass-Ratio on Two-Degree-of-Freedom Vortex-Induced Vibrations

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china Ocean Engineering 2013年第4期27卷 537-548页

作者：马文亮张建华 School of Civil Engineering and Communication North China University of Water Resources and Electric Power

Through a serious application of an overlapping mesh, vortex-induced vibration （VIV） of low-mass-rationale cylinders was computed in the range of 1.0x 103〈Re〈2.0x104. An overlapping mesh is more controllable to deal with the dynamic mesh since there is no necessity to regenerate grids in this complete computational domain. Only boundary nodes are utilized to dispose of all steps each time. It is discovered that the cross-flow amplitudes can increase by approximately 30% in the resonance area when the in-line degree of freedom is taken into account. But the cross-flow amplitudes do not have any change outside the resonance area. In its mass ratio （m＊= mass of cylinder/mass of displaced water） ranging from 1.0 to 40, the ratios of in-line amplitudes to cross-flow amplitudes decrease with the increasing m＊, especially as m＊〈2.5, the ratios will be larger than 10%. Moreover, the phase differences between in-line displacements and cross-flow displacements also reduce as m＊ increases. However, the correlation coefficients between displacements at two directions are so random even a bit low. With regards to vortex mode, the ＇2S＇ mode and the ＇2P＇ mode are very applicable to the present work. Effect of Re is also investigated, this paper aims to prove that the ratios of amplitudes between two directions have few relations with Re, and then the relationship between relative amplitudes and mass ratios can be decoded hereof.

关键词： Ocean engineering Oceanography

Research progresses of nanomaterials as lubricant additives

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Friction 2024年第7期12卷 1347-1391页

作者： Zhengquan JIANG Yankun SUN Bokang LIU Laigui YU Yuping TONG Mingming YAN Zhongzheng YANG Yongxing HAO Linjian SHANGGUAN Shengmao ZHANG Weihua LI School of Materials Science and Engineering North China University of Water Resources and Electric PowerZhengzhou 450045China Institute of Special Friction and Lubricating Materials North China University of Water Resources and Electric PowerZhengzhou 450045China Nanomaterials Engineering Research Center Henan UniversityKaifeng 475001China School of Mechanical Engineering North China University of Water Resources and Electric PowerZhengzhou 450045China

Friction and wear are unavoidable in mechanical *** use of lubricants with nano-additives can effectively reduce friction and wear,which is of great significance to saving energy and protecting the *** present,great progress has been made in the scientific research and industrial application of nano-additives for *** paper mainly introduces the types of nano-additives for lubricants(such as carbon nanomaterials,nano-metals,nano-oxides,sulfides,complexes,polymers,etc.),the tribological properties of lubricants with different components of nano-additives,and the lubrication mechanisms of the nano-additives(including tribofilm formation,rolling ball bearing effect,repairing effect,polishing effect,and synergistic effect).It also deals with the dispersion of nano-additives in lubricants and the influences of their particle size and microstructure on the tribological properties of *** review outlines the performance requirements of nano-additives in different lubrication states,discusses the use of nano-additives in challenging working conditions,and identifies various industrial oil nano-additives with reference to the appropriate options in diverse working ***,the existing problems of nano-additives and their application prospects are *** review,hopefully,would help to shed light on the design and synthesis of novel high-performance nano-additives and promote their application in engineering.

关键词： nanomaterials lubricant additive lubrication mechanism research progress