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Frontiers of Chemical Science and Engineering 2024年第3期18卷 1-12页

作者： Li Zhao Xinru Liu Zihao Ye Bin Hu Haoyu Wang Ji Liu Bing Zhang Qiang Lu National Engineering Research Center of New Energy power generation North China Electric Power UniversityBeijing102206China

The composition of biomass pyrolysis gas is complex,and the selective separation of its components is crucial for its further ***-incorporated nitrogen-doped materials exhibit enormous potential,whereas the relevant adsorption mechanism is still ***,16 metal-incorporated nitrogen-doped carbon materials were designed based on the density functional theory calculation,and the adsorption mechanism of pyrolysis gas components H2,CO,CO_(2),CH_(4),and C2H6 was *** results indicate that metal-incorporated nitrogen-doped carbon materials generally have better adsorption effects on CO and CO_(2)than on H_(2),CH_(4),and C_(2)H_(6).Transition metal Mo-and alkaline earth metal Mg-and Ca-incorporated nitrogen-doped carbon materials show the potential to separate CO and CO_(2).The mixed adsorption results of CO_(2)and CO further indicate that when the CO_(2)ratio is significantly higher than that of CO,the saturated adsorption of CO_(2)will precede that of ***,the three metal-incorporated nitrogen-doped carbon materials can selectively separate CO_(2),and the alkaline earth metal Mg-incorporated nitrogen-doped carbon material has the best *** study provides theoretical guidance for the design of carbon capture materials and lays the foundation for the efficient utilization of biomass pyrolysis gas.

关键词： CO_(2)capture biomass pyrolysis gas selective adsorption carbon materials first-principles

Stall Evolution Mechanism of a Centrifugal Compressor with a Wide-Long Vaneless Diffuser

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Journal of Thermal Science 2024年第3期33卷 899-913页

作者： ZHANG Lei KANG Jiacheng LANG Jinhua AN Guangyao ZHANG Qian WANG Longyao WANG Qifang department of power Engineering North China Electric Power UniversityBaoding071003China Hebei Key Laboratory of Low Carbon and High Efficiency power generation Technology North China Electric Power UniversityBaoding071003China

The rotating stall mechanism is of high importance for the stability of centrifugal compressors and thermal power *** majority of research concerning this topic has concentrated on the initial stall ***,the evolution of stall cells in wide-long diffusers has not been comprehensively *** this paper,the causes of rotating stall in the wide-long diffuser and the three-dimensional evolution mechanism of stall cells during the stall process were thoroughly *** the stall induction phase,an annulus vortex structure was found in the reverse-flow zone near the hub side of the diffuser outlet,which was the initial form of stall *** whole evolution process of stall cells was divided into three phases as the flow rate *** the initial stall phase,the dynamic equilibrium was built under effects of the impeller wake and the adverse pressure *** a result,the number of stall cells was kept at seven and the size of stall cells remained *** the transition phase,the flow in the diffuser became *** cells extended to the impeller outlet,and the effect of the wake flow was strengthened *** cells started integrating and separating *** a result,the number and propagation speed of stall cells varied periodically at a constant mass flow *** the deep stall phase,the size of stall cells remained unchanged,and the number of stall cells kept at *** study has important practical guidance and engineering value for the high-efficiency design and safe operation of centrifugal compressors.

关键词： centrifugal compressor wide-long vaneless diffuser stall evolution mechanism wake flow

Wide frequency phonons manipulation in Si nanowire by introducing nanopillars and nanoparticles

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Chinese Physics B 2024年第4期33卷 78-84页

作者：李亚涛刘英光李鑫李亨宣王志香张久意 Hebei Key Laboratory of Low Carbon and High Efficiency power generation Technology North China Electric Power UniversityBaoding 071003China

The combination of different nanostructures can hinder phonons transmission in a wide frequency range and further reduce the thermal conductivity(TC).This will benefit the improvement and application of thermoelectric conversion,insulating materials and thermal barrier coatings,*** this work,the effects of nanopillars and Ge nanoparticles(GNPs)on the thermal transport of Si nanowire(SN)are investigated by nonequilibrium molecular dynamics(NEMD)*** analyzing phonons transport behaviors,it is confirmed that the introduction of nanopillars leads to the occurrence of lowfrequency phonons resonance,and nanoparticles enhance high-frequency phonons interface scattering and *** results show that phonons transport in the whole frequency range can be strongly hindered by the simultaneous introduction of nanopillars and *** addition,the effects of system length,temperature,sizes and numbers of nanoparticles on the TC are *** work provides useful insights into the effective regulation of the TC of nanomaterials.

关键词： resonant structure nanoparticles nanopillars phonon transport thermal conductivity

Numerical Simulation Study on Influence of Equation of State on Internal Flow Field and Performance of S-CO_(2)Compressor

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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

Characterization of electrical Tree Degradation of Epoxy Resin under Thermal and Temperature Stresses by Photoelastic Effect

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Chinese Journal of electrical Engineering 2024年第1期10卷 12-20页

作者： Hein Htet Aung Yuhuai Wang Jin Li Ying Zhang Tatsuo Takada School of electrical and Information Engineering Tianjin UniversityTianjin 300072China department of power generation and Transformation Engineering Baoding Technical College of Electric PowerBaoding 071051China Measurement and electric Machine Control Laboratory Tokyo City UniversityTokyo 158-8557Japan

Epoxy resin is widely used in the support,insulation,and packaging components of electrical equipment owing to their excellent insulation,thermal,and mechanical ***,epoxy-resin insulation often suffers from thermal and mechanical stresses under extreme environmental conditions and a compact design,which can induce electrical tree degradation and insulation failure in electrical *** this study,the photoelastic method is employed to investigate the thermal-mechanical coupling stress dependence of the electrical treeing behavior of epoxy *** electrical tree growth morphology and stress distribution were observed using the photoelastic *** correlation between the tree length and overall accumulated damage with an increase in mechanical stress is *** results show that compressive stress retards the growth of electrical trees along the electric field,while tensile stress has accelerating *** proves that the presence of thermal stress can induce more severe accumulated damage.

关键词： Epoxy resin electrical tree degradation thermal stress mechanical stress photoelastic effects

Damping Characteristic Analysis and Optimization of Wind-thermal-bundled power Transmission by LCC-HVDC Systems

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Journal of Modern power Systems and Clean Energy 2024年第1期12卷 299-312页

作者： Liwen Zheng Shiying Ma the power System department China Electric Power Research InstituteBeijing 100192China

With the rapid development of renewable energy,wind-thermal-bundled power transmission by line-commutated converter based high-voltage direct current(LCC-HVDC)systems has been widely *** dynamic interaction mechanisms among permanent magnet synchronous generators(PMSGs),synchronous generators(SGs),and LCC-HVDC system become *** deal with this issue,a path analysis method(PAM)is proposed to study the dynamic interaction mechanism,and the damping reconstruction is used to analyze the damping characteristic of the ***,based on the modular modeling,linearized models for the PMSG subsystem,the LCC-HVDC subsystem,and the SG subsystem are ***,based on the closed-loop transfer function diagram of the system,the disturbance transfer path and coupling relationship among subsystems are analyzed by the PAM,and the damping characteristic analysis of the SG-dominated oscillation mode is studied based on the damping *** with the PAM,the small-signal model of the system is obtained and eigenvalue analysis results are ***,the effect of the control parameters on the damping characteristic is analyzed and the conclusions are verified by time-domain ***,the penalty functions of the oscillation modes and decay modes are taken as the objective function,and an optimization strategy based on the Monte Carlo method is proposed to solve the parameter optimization *** simulation results are presented to validate the effectiveness of the proposed strategy.

关键词： Wind-thermal-bundled power transmission line-commutated converter based high-voltage direct current(LCC-HVDC) path analysis method(PAM) damping characteristic analysis Monte Carlo method

A New Method for the Aging Evaluation of Oil-Paper Insulation Using η-Butanol and Methanol

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CSEE Journal of power and Energy Systems 2024年第2期10卷 717-726页

作者： Jianyi Wang Yuanxiang Zhou Jun Liu Zhaowei Wang Song Bai Jiayu Lu department of High Voltage China Electric Power Research InstituteBeijing 100192China State Key Laboratory of power Grid Environmental Protection Beijing 100192China electrical Engineering department Tsinghua UniversityBeijing 100084China Solar Storage Division of State Key Lab of power System and generation Equipment School of Electrical EngineeringXinjiang UniversityUrumqi 830047China State Grid Wuwei electric power Supply Company Wuwei 733000China

To improve the accuracy and efficiency of the aging life prediction and assessment of transformer oil-paper insulation,and to make up for the deficiencies of traditional characterizers,such as 2-furfural,carbon monoxide,and carbon dioxide,a method for the simultaneous determination of methanol,ethanol,n−propanol,and η-butanol in oil with a single injection is established by headspace-gas chromatography-mass *** measured results show that the determination limits of the four alcohol characterizers can be controlled to 10μg/kg *** on this method,the change patterns of the above four alcohols with thermal aging time and degree of polymerization are obtained through thermal aging experimental ***,η-propanol,and η-butanol in oil indicate nearly linear correlations with thermal aging time and degree of polymerization,similar to that of *** analyzing 52 sets of measured data of 500 kV EHV transformers in operation,η-butanol is found to have excellent performance,and a new method to evaluate the aging state of oil-paper insulation employing η-butanol and methanol is proposed along with the aging attention value *** measured data of 500 kV EHV transformers in operation indicate that the combination of η-butanol and methanol as the preferred characterizers can effectively compensate for the shortcoming of traditional characterizers in the early stages of aging,and the feasibility of the method is *** possible pathways for the generation of η-butanol by cellulose cleavage during the aging of oil-paper are proposed from the chemical structure of cellulose.

关键词： Aging characterization determination method methanol η-butanol oil-paper insulation 500 kV transformers

Analysis on carbon emission reduction intensity of fuel cell vehicles from a life-cycle perspective

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Frontiers in Energy 2024年第1期18卷 16-27页

作者： Ziyuan TENG Chao TAN Peiyuan LIU Minfang HAN Fuel Cell and Energy Storage Center Department of Energy and Power EngineeringState Key Laboratory of Control and Simulation of Power Systems and Generation EquipmentTsinghua UniversityBeijing 100084China

The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and *** paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys,including hydrogen production and packing in chlor-alkali plants,transport by tube trailers,storage and refueling in hydrogen refueling stations(HRSs),and application for use in two different *** also conducted a comparative study for battery electric vehicles(BEVs)and internal combustion engine vehicles(ICEVs).The result indicates that hydrogen fuel cell vehicle(FCV)has the best environmental performance but the highest energy ***,a sufficient hydrogen supply can significantly reduce the carbon intensity and FCV energy cost of the current *** carbon emission for FCV application has the potential to decrease by 73.1%in City A and 43.8%in City *** only takes 11.0%–20.1%of the BEV emission and 8.2%–9.8%of the ICEV *** cost of FCV driving can be reduced by 39.1%in City *** improvement can be obtained with an economical and“greener”hydrogen production pathway.

关键词： hydrogen energy life-cycle assessment(LCA) fuel cell vehicle carbon emission energy cost

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

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Plasma Science and Technology 2024年第1期26卷 42-49页

作者：耿江海林果王平丁玉剑丁杨俞华 department of electric power Engineering North China Electric Power UniversityBaoding 071003People’s Republic of China China electric power Research Institute Beijing 100192People’s Republic of China Xinjiang electric power Company Research Institute Urumchi 830000People’s Republic of China Shanxi electric power Company Research Institute Taiyuan 030001People’s Republic of China

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude *** this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 *** experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical *** duration of the dark period and the critical charge of streamer-toleader transition were obtained at high *** on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader *** with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified *** the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

关键词： streamer-to-leader transition model high altitude streamer stem convective diffusion radial thermal expansion

Investigating Load Regulation Characteristics of a Wind-PV-Coal Storage Multi-power generation System

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Energy Engineering 2024年第4期121卷 913-932页

作者： Zhongping Liu Enhui Sun Jiahao Shi Lei Zhang Qi Wang Jiali Dong Sinopec Star Co. Ltd.Zhengzhou450000China Hebei Key Laboratory of Low Carbon and High Efficiency power generation Technology North China Electric Power UniversityBaoding071003China

There is a growing need to explore the potential of coal-fired power plants(CFPPs)to enhance the utilization rate of wind power(wind)and photovoltaic power(PV)in the green energy *** study developed a load regulation model for a multi-power generation system comprising wind,PV,and coal energy storage using realworld *** power supply process was divided into eight fundamental load regulation scenarios,elucidating the influence of each scenario on load *** the framework of the multi-power generation system with the wind(50 MW)and PV(50 MW)alongside a CFPP(330 MW),a lithium-iron phosphate energy storage system(LIPBESS)was integrated to improve the system’s load regulation *** energy storage operation strategy was formulated based on the charging and discharging priority of the LIPBESS for each basic scenario and the charging and discharging load calculation method of LIPBESS auxiliary *** optimization using the particle swarm algorithm,the optimal capacity of LIPBESS was determined to be within the 5.24-4.88 MWh *** an economic perspective,the LIPBESS operating with CFPP as the regulating power source was 49.1% lower in capacity compared to the renewable energy-based storage mode.

关键词： Wind power coal-fired power PV multi-power generation system lithium-iron phosphate energy storage system