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Journal of Thermal Science 2024年第3期33卷 888-898页

作者： ZHANG Lei YANG Zhenyu SUN Enhui ZHANG Qian AN Guangyao YUAN Wei Hebei Key Laboratory of Low Carbon and High Efficiency power Generation Technology North China Electric Power UniversityBaoding071003China school of Energy Power&Mechanical EngineeringNorth China Electric Power UniversityBaoding071028China

The low power consumption of the near-critical compressor is the key factor for the high efficiency of supercritical CO_(2)Brayton *** the numerical simulation of the compressor,the rapid changes in the thermophysical properties of the CO_(2)near the critical point make it difficult to capture the condensation *** paper investigates the influence of fluid physical properties on the condensation ***,the differences in the physical properties of CO_(2)in the SRK EOS(equation of state),PR EOS,and SW EOS are ***,the simulation of nozzles and compressors were carried out and *** show that the condensation positions predicted by the three EOSs are basically the *** with SW EOS,the disparities between the maximum condensation mass fraction predicted by the PR and SRK EOSs is5.7%and 11.5%,and that of total pressure ratio is 0.3%and 3.8%,*** results show that PR EOS can be considered for numerical simulation in engineering *** its physical property calculation results are closer to the actual physical properties while the physical properties change more gently,it has considerable accuracy and numerical stability.

关键词： supercritical carbon dioxide equation of state centrifugal compressor numerical simulation condensation

Infrared and Visible Image Fusion Based on Res2Net-Transformer Automatic Encoding and Decoding

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Computers, Materials & Continua 2024年第4期79卷 1441-1461页

作者： Chunming Wu Wukai Liu Xin Ma Key Laboratory of Modern power System Simulation and Control&Renewable Energy Technology School of Electrical EngineeringNortheast Electric Power UniversityJilin132012China school of electrical engineering Northeast Electric Power UniversityJilin132012China school of Aeronautical engineering Jilin Institute of Chemical TechnologyJilin132022China

A novel image fusion network framework with an autonomous encoder and decoder is suggested to increase thevisual impression of fused images by improving the quality of infrared and visible light picture fusion. The networkcomprises an encoder module, fusion layer, decoder module, and edge improvementmodule. The encoder moduleutilizes an enhanced Inception module for shallow feature extraction, then combines Res2Net and Transformerto achieve deep-level co-extraction of local and global features from the original picture. An edge enhancementmodule (EEM) is created to extract significant edge features. A modal maximum difference fusion strategy isintroduced to enhance the adaptive representation of information in various regions of the source image, therebyenhancing the contrast of the fused image. The encoder and the EEM module extract features, which are thencombined in the fusion layer to create a fused picture using the decoder. Three datasets were chosen to test thealgorithmproposed in this paper. The results of the experiments demonstrate that the network effectively preservesbackground and detail information in both infrared and visible images, yielding superior outcomes in subjectiveand objective evaluations.

关键词： Image fusion Res2Net-Transformer infrared image visible image

Thermo-Flow Performances for the Main-Auxiliary Integrated Natural Draft Dry Cooling System

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Journal of Thermal Science 2024年第3期33卷 1010-1025页

作者： ZHANG Zongyang HOU Yichen ZHOU Hanyu JIA He CHEN Lei KONG Yanqiang WANG Weijia YANG Lijun DU Xiaoze Key Laboratory of power Station Energy Transfer Conversion and System of Ministry of Education School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

Recently,natural draft dry cooling system with the main-auxiliary integrated air-cooled heat exchangers in the up and lower layers,has drawn attention to the electric power *** research firstly develops two physical models for the integrated cooling system,namely Case A and Case *** Case A,the main air-cooled heat exchanger is arranged in the upper layer and the auxiliary air-cooled heat exchanger arranged in the lower layer,while in Case B,the two heat exchanger systems are arranged in the opposite *** then,directing at the engineering TMCR and TRL 1 working conditions,the unit-local-overall thermo-flow characteristics of Case A and Case B are obtained and compared by numerical *** findings show that,for the auxiliary air-cooled exchanger,Case A has obviously higher cooling performances than Case B,with the difference varying from 5.46%to 7.55%.Whereas,for the main air-cooled exchanger,Case B shows the recovered cooling performances,with the difference changing from 1.15%to 2.99%.Case A is preferably recommended to the engineering application in consideration of more strict cooling demand of the auxiliary cooling ***,this research will provide some theoretical guidelines for the design and construction of the main-auxiliary integrated natural draft dry cooling system.

关键词： integrated dry cooling system main air-cooled heat exchanger auxiliary air-cooled heat exchanger upper layer and lower layer thermo-flow performances

Numerical investigations of the interactions between bubble induced shock waves and particle based on OpenFOAM

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Journal of Hydrodynamics 2024年第2期36卷 355-362页

作者： Jia-xin Yu Jin-sen Hu Yu-hang Liu Yi-fan Liu Dan Gao Yu-ning Zhang Key Laboratory of power Station Energy Transfer Conversion and System Ministry of EducationSchool of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The presence of particles and the shock waves generated by the cavitation bubbles can significantly affect the safety and the performance of hydrodynamic *** the present paper,the shock waves generated by cavitation bubble collapsing near the particle are numerically investigated based on the OpenFOAM together with the numerical schlieren for the shock wave *** numerical results reveal that the stand-off distance is one of the paramount factors affecting the interactions between the particle and the shock *** different kinds of shock waves(e.g.,bubble-inception,jet formation,particle reflected and jet-split shock waves)are observed during the bubble collapsing near the *** stand-off distance smaller than 0.5 or larger than 1.1,the maximum pressure at particle surface generated by the bubble growth can surpass those of the collapse stage.

关键词： Particle-bubble interaction shockwaves jetdynamics

Physics of cavitation near particles

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Journal of Hydrodynamics 2024年第1期36卷 102-118页

作者： Jia-xin Yu Xiao-yu Wang Jun-wei Shen Jin-sen Hu Xiang-qing Zhang Da-qing He Yu-ning Zhang Key Laboratory of power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The combined effect of cavitation and silt abrasion presents a great challenge and threat to secure the operation and the efficiency of hydraulic machineries working in sediment-laden *** present paper critically reviews the current research progress on the interaction mechanisms of the bubbles and the ***,the analytical models including boundary treatment methods for predicting the jet dynamics of the bubble collapse near particles are ***,the bubble collapsing dynamics,jet dynamics and shock wave characteristics near particles are revealed both experimentally and ***,the bubble-particle-wall system is investigated with a focus on microjets.

关键词： Cavitation bubble particle jet shock wave

Transient Stability Preventive Control of Wind Farm Connected power System Considering the Uncertainty

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Energy engineering 2024年第6期121卷 1637-1656页

作者： Yuping Bian Xiu Wan Xiaoyu Zhou school of electric power engineering Nanjing Institute of TechnologyNanjing211167China

To address uncertainty as well as transient stability constraints simultaneously in the preventive control of windfarm systems, a novel three-stage optimization strategy is established in this paper. In the first stage, the probabilisticmulti-objective particle swarm optimization based on the point estimate method is employed to cope with thestochastic factors. The transient security region of the system is accurately ensured by the interior point methodin the second stage. Finally, the verification of the final optimal objectives and satisfied constraints are enforcedin the last stage. Furthermore, the proposed strategy is a general framework that can combine other optimizationalgorithms. The proposed methodology is tested on the modified WSCC 9-bus system and the New England 39-bussystem. The results verify the feasibility of the method.

关键词： Transient preventive control chance-constrained programming multi-objective PSO TSCOPF wind farm

Estimating Critical Clearing Time of Grid Faults Using DA of State-Reduction Model of power Systems

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CSEE Journal of power and Energy Systems 2024年第2期10卷 807-820页

作者： Yang Liu Zhongyang Chen Huanjin Yao Lin Yi Q.H.Wu school of electric power engineering South China University of TechnologyGuangzhou 510640China China Southern power Grid Research Institute Guangzhou 510663China

This paper proposes a critical clearing time (CCT) estimation method by the domain of attraction (DA) of a state-reduction model of power systems using sum of squares (SOS) programming. By exploiting the property of the Jacobian matrix and the structure of the boundary of the DA, it is found the DA of the state-reduction model and that of the full model of a power system are topological isomorphism. There are one-to-one correspondence relationships between the number of equilibrium points, the type of equilibrium points, and solutions of the two system models. Based on these findings, an expanding interior algorithm is proposed with SOS programming to estimate the DA of the state-reduction model. State trajectories of the full model can be transformed to those of the state-reduction model by orthogonal or equiradius projection. In this way, CCT of a grid fault is estimated with the DA of the state-reduction model. The calculational burden of SOS programming in the DA estimation using the state-reduction model is rather small compared with using the full model. Simulation results show the proposed expanding interior algorithm is able to provide a tight estimation of DA of power systems with higher accuracy and lower time costs.

关键词： Critical clearing time domain of attraction expanding interior algorithm state-reduction model SOS programming

Numerical simulation and parameter optimization of Coriolis force scale measurement process based on DEM

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Particuology 2024年第7期90卷 128-139页

作者： Haiting Liu Yong Yang Xiangliang Wang Jiewen Deng Bingbing Wang school of Energy and power engineering Northeast Electric Power UniversityJilin132012China CNBM Hefei Mechanical&electrical engineering Technology Co.Ltd Hefei230051China

The Coriolis force method is a recently developed and highly regarded direct measurement technique that enables high-precision measurement of bulk *** operational parameters and variations thereof directly influence the measurement accuracy of the *** this study,a measurement correction coefficient is introduced to improve the calculation method for mass flow rate of the *** DEM is employed to simulate the motion of particle groups within the Coriolis force scale under different parameters,and the effects of various structural and operational parameters on the measurement results are *** research findings indicate that a lower rotational speed leads to more stable instantaneous measurement results,although the measurement error is relatively *** the rotational speed exceeds 300 rpm,the measurement error remains within 15%.For materials with a radius of 1–2 mm,the variation range of precision error is approximately 0.4%.Among the structural parameters,the radius of the measurement wheel has the most significant impact on the measurement results,wherein a larger measurement wheel radius corresponds to a smaller measurement *** horizontal angle of the blades follows as the next influential parameter,with a clockwise rotation and a horizontal angle of 30°resulting in a measurement error below 2%.

关键词： Parameter optimization Discrete element method Coriolis force scale Measurement error Numerical simulation

Risk-averse Robust Interval Economic Dispatch for power Systems with Large-scale Wind power Integration

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CSEE Journal of power and Energy Systems 2024年第1期10卷 105-116页

作者： Zhenjia Lin Haoyong Chen Jinbin Chen Jianping Huang Mengshi Li school of electric power engineering South China University of TechnologyGuangzhou 510641China Department of electrical engineering Technical University of DenmarkDenmark

This paper presents a robust interval economic dispatch(RIED)model for power systems with large-scale wind power *** from existing interval optimization(IO)approaches that merely rely on the upper and lower boundaries of random variables,the distribution information retained in the historical data is introduced to the IO method in this *** on the available probability distribution function(PDF),wind power curtailment and load shedding are quantified as the operational risk and incorporated into the decision-making *** this model,we need not rely on the forecasted value of wind power,which is randomly fluctuating and quite ***,when the PDFs of wind power are taken into account,the resulting dispatch solution makes a good tradeoff between the generation cost and the operational ***,the RIED model yields an optimal dispatch solution for thermal units and the allowable intervals of wind power for the wind farms,which efficiently mitigates the uncertainty in wind power generation and provides more practical suggestions for system *** studies are conducted on a modified IEEE-118 bus system and the results verify the effectiveness of the proposed RIED model.

关键词： Economic dispatch interval optimization risk-averse wind power generation

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