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Studying the variable energy band structure for energy storage materials in charge/discharge process

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Chinese Chemical Letters 2024年第2期35卷 584-589页

作者： Xuancheng Chen Yu Huan Ningqiang Sun Yuanhui Su Xuesong Shen Guoqing Li jiaqi Zhang Tao Wei University of jinan Ji'nan 250022China Weichai power co. Ltd.Weifang 261061China

So far,a clear understanding about the relationship of variable energy band structure with the corresponding charge-discharge process of energy storage materials is still ***,using optical spectroscopy(red-green-blue(RGB)value,reflectivity,transmittance,UV-vis,XPS,UPS)to studyα-co(OH)_(2) electrode working in KOH electrolyte as the research object,we provide direct experimental evidence that:(1)The intercalation of OH-ions will reduce the valence/conduction band(VB and CB)and band gap energy(Eg)values;(2)The deintercalation of OH-ions corresponds with the reversion of VB,CB and E_(g) to the initial values;(3)The color of co(OH)_(2) electrode also exhibit regular variations in RGB value during the charge-discharge process.

关键词： Variable energy band structure Energy storage materials Charge-discharge process Optical spectroscopy Supercapacitors

Numerical Analysis of Heat Transfer Characteristics to Supercritical co_(2) in a Vertical Mini-Channel:Transition and Pseudo-Boiling

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Journal of Thermal Science 2024年第1期33卷 101-113页

作者： YUAN Baoqiang WANG Wei XIN Gongming DU Wenjing School of Energy and power Engineering Shandong UniversityJi'nan 250061China

Large eddy simulations have been conducted to study upward transitional flows and heat transfer characteristics of supercritical co_(2) in a vertical *** numerical simulation was carried out on a modified buoyantPimpleFOAM solver in OpenFOAM 7,and was verified using experiment *** results indicate that increasing the Grashof numbers can reduce the flow stability and make the flow transition *** are four stages of heat transfer in the transition process,i.e.,weakened,improved,recovered and normal heat *** heat transfer phenomena in the transition process were explained from three perspectives:thermal boundary layer theory,turbulent transport and pseudo-boiling *** transfer enhancement during transition is related to the transport of supercritical molecular clusters,and these molecular clusters are regarded as pseudo-bubbles in pseudo-boiling *** flow pattern of the pseudo-phases in the dia-Widom process contains single-phase flow,steady pseudo-film flow,unsteady pseudo-film flow,partial pseudo-bubbles flow and flocculent pseudo-film ***-bubbles have similar behaviors to subcritical bubbles,i.e.,break-up,deformation,condensation and *** researches in this work are favorable for understanding the heat transfer mechanism of supercritical fluids during flow transition.

关键词： supercritical heat transfer large eddy simulation transition pseudo-boiling

Visualisation and Heat Transfer Performance of Mini-Channel Flat Heat Pipe with a Binary Mixture

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Journal of Thermal Science 2024年第5期33卷 1712-1725页

作者： FAN Gaoting TANG Aikun CAI Tao SHAN Chunxian PAN Jun jiN Yi School of Energy and power Engineering Jiangsu UniversityZhenjiang 212013China jiangsu jinhe Energy Technology co.ltd Zhenjiang 212400China

To unravel the intricacies of two-phase gas-liquid flow characteristics and heat transfer behavior,an array mini-channel gravity plate heat pipe(AMGPHP)is proposed in this work,which allows for observing the internal changes in the state of the working *** flow patterns such as pool flow,columnar flow,and slug flow,are experimentally explored and analyzed in *** is found that the optimal volume fill ratio is 20%by utilizing start-up time and thermal resistance as performance evaluation *** this fill ratio,a medium optimization strategy by blending ethanol within R141b is proposed and *** comparison to pure working fluids,the heat transfer performance of AMGFHP in the binary fluid has been significantly augmented due to temperature and concentration shifts resulting from disparate boiling *** the 10%volume fraction ethanol blending condition,the equivalent thermal conductivity of the heat pipe is dramatically elevated,with a value of 3110 W/(m·℃),along with the reduction of the minimum start-up power to 4 *** general,applying such a medium to heat pipes has considerable potential in practical applications.

关键词： flat heat pipe mini-channel visualisation two-phase flow binary mixtures thermal performance

Mitigating kinetic hindrance of single-crystal Ni-rich cathodes through morphology modulation, nickel reduction, and lithium vacancy generation achieved by terbium doping

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Journal of Energy Chemistry 2024年第10期97卷 566-574页

作者： jiyuan jian Shuang Lin Guokang Han Xianglian Zhan Yinghui Shan Rang Xiao Ziwei Liu Dandan Sun Xin Zhang Qingjie Zhou Geping Yin Hua Huo Yulin Ma Pengjian Zuo Xinqun Cheng Chunyu Du State Key Laboratory of Space power-sources School of Chemistry and Chemical Engineering Harbin Institute of Technology Zibo Torch Energy co.ltd

Single crystallization has proven to be effective in enhancing the capacity and stability of Ni-rich LiNi1-x-ycoxMnyO2（SNCM） cathode materials,particularly at high cut-off ***,the synthesis of high-quality single-crystal particles remains challenging because of severe particle agglomeration and irregular ***,the limited kinetics of solid-phase Li+diffusion pose a significant concern because of the extended diffusion path in large single-crystal *** address these challenges,we developed a Tb-doped single-crystal LiNi0.83co0.11Mn0.06O2（SNCM-Tb） cathode material using a straightforward mixed molten salt sintering *** Tb-doped Ni-rich single crystals presented a quasi-spherical morphology,which is markedly different from those reported in previous ***4+oping significantly enhanced the dynamic transport of Li+ions in the layered oxide phase by reducing the Ni valence state and creating Li vacancies.A SNCM-Tb material with 1 at% Tb doping shows a Li+diffusion coefficient up to more than 9 times higher than pristine SNCM in the non-diluted *** situ X-ray diffraction analysis demonstrated a significantly facilitated H1-H2-H3 phase transition in the SNCM-Tb materials,thereby enhancing their rate capacity and structural ***-Tb exhibited a reversible capacity of 186.9 mA h g-1at 5 C,retaining 94.6% capacity after 100 cycles at 0.5 C under a 4,5 V *** study elucidates the Tb4+doping mechanisms and proposes a scalable method for enhancing the performance of single-crystal Ni-rich NCM materials.

关键词： Li+ diffusion kinetics Lithium-ion batteries Ni-rich layered oxides Single crystals Tb4+ doping

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

Primary frequency control considering communication delay for grid-connected offshore wind power systems

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Global Energy Interconnection 2024年第3期7卷 241-253页

作者： Xueping Pan Qijie Xu Tao Xu jinpeng Guo Xiaorong Sun Yuquan Chen Qiang Li Wei Liang School of Electrical and power Engineering Hohai UniversityNanjing 211100P.R.China Electric power Research Institute of State Grid jiangsu Electric power co.ltd Nanjing 211103P.R.China

Offshore wind farms are becoming increasingly distant from onshore centralized control centers,and the communication delays between them inevitably introduce time delays in the measurement signal of the primary frequency *** causes a deterioration in the performance of the primary frequency control and,in some cases,may even result in frequency instability within the power ***,a frequency response model that incorporates communication delays was established for power systems that integrate offshore wind *** Padéapproximation was used to model the time delays,and a linearized frequency response model of the power system was derived to investigate the frequency stability under different time *** influences of the wind power proportion and frequency control parameters on the system frequency stability were *** addition,a Smith delay compensation control strategy was devised to mitigate the effects of communication delays on the system frequency ***,a power system incorporating offshore wind power was constructed using the MATLAB/Simulink *** simulation results demonstrate the effectiveness and robustness of the proposed delay compensation control strategy.

关键词： Offshore wind power Primary frequency control Time delay Padéapproximation Time-delay compensation control

Design strategy and relevant flow mechanisms of highly loaded 3D compressor tandem cascades

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Chinese Journal of Aeronautics 2024年第7期37卷 220-235页

作者： Xiaochen MAO Yunyu WANG Zhihua DING Hao CHENG Bo LIU School of power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi’an 710129China Xi’an Thermal power Research Institute co.ltd Xi’an 710072China

To investigate the design strategy of highly loaded tandem cascades at both the midspan and endwall,the overall performance and flow mechanisms of four typical tandem cascades based on the optimization were analyzed from multiple perspectives *** results show that the interference effects on the Front Blade(FB)and Rear Blade(RB)should not be overlooked during the design phase,and the design strategies at the midspan and endwall are completely *** the midspan,the optimization aims to increase the interference effects and the strength of the gap jet while maintaining the same load on the FB and ***,the endwall optimal airfoil exhibits weakening interference effects,advancement of the gap jet location,and load transfer from the FB to *** further analysis of flow characteristics,the midspan optimal airfoil is beneficial for inhibiting the low-energy fluid from interacting with the suction surface of RB under the design condition,but results in earlier occurrence of corner *** endwall optimal airfoil helps suppress the development of the secondary flow and delay the onset of corner ***,by combining the benefits of these two design approaches,additional forward sweep effects are achieved,further enhancing the performance of the tandem cascade.

关键词： Tandem cascade Interference effect Vortex structure Load split compressor

Alleviating the anisotropic microstructural change and boosting the lithium ions diffusion by grain orientation regulation for Ni-rich cathode materials

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Journal of Energy Chemistry 2024年第1期88卷 213-222,I0005页

作者： Xinyou He Shilin Su Bao Zhang Zhiming Xiao Zibo Zhang Xing Ou Engineering Research Center of the Ministry of Education for Advanced Battery Materials School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083HunanChina Zhejiang power New Energy co.ltd Zhuji 311899ZhejiangChina

Generally,layered Ni-rich cathode materials exhibit the morphology of polycrystalline secondary sphere composed of numerous primary *** the arrangement of primary particles plays a very important role in the properties of Ni-rich *** disordered particle arrangement is harmful to the cyclic performance and structural stability,yet the fundamental understanding of disordered structure on the structural degradation behavior is ***,we have designed three kinds of LiNi_(0.83)co_(0.06)Mn_(0.11)O_(2) cathode materials with different primary particle orientations by regulating the precursor coprecipitation *** finite element simulation and in-situ characterization,the Li^(+)transport and structure evolution behaviors of different materials are ***,the smooth Li^(+)diffusion minimizes the reaction heterogeneity,homogenizes the phase transition within grains,and mitigates the anisotropic microstructural change,thereby modulating the crack evolution ***,the optimized structure evolution ensures radial tight junctions of the primary particles,enabling enhanced Li^(+)diffusion during dynamic ***-loop bidirectional enhancement mechanism becomes critical for grain orientation regulation to stabilize the cyclic *** precursor engineering with particle orientation regulation provides the useful guidance for the structural design and feature enhancement of Ni-rich layered cathodes.

关键词： Ni-rich cathode Grain orientation regulation Anisotropic microstructural change Precursor engineering Li~+-ions diffusion

Growth and inhibition of zinc anode dendrites in Zn-air batteries:Model and experiment

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Chinese Journal of Chemical Engineering 2024年第3期67卷 268-281页

作者： Cuiping He Qingyi Gou Yanqing Hou jianguo Wang Xiang You Ni Yang Lin Tian Gang Xie Yuanliang Chen Kunming University of Science and Technology State Key Laboratory of Complex Nonferrous Metal Resources Clean UtilizationKunming 650093China Kunming University of Science and Technology Faculty of Metallurgical and Energy EngineeringKunming 650093China China copper co.ltd KunmingYunnan 650051China State Key Laboratory of Advanced Metallurgy for Non-ferrous Metals Kunming 650051China Sichuan Shunying power Battery Materials co.ltd Sichuan 620076China

Zinc(Zn)-air batteries are widely used in secondary battery research owing to their high theoretical energy density,good electrochemical reversibility,stable discharge performance,and low cost of the anode active material ***,the Zn anode also leads to many challenges,including dendrite growth,deformation,and hydrogen precipitation *** this context,Zn dendrite growth has a greater impact on the cycle *** this dissertation,a dendrite growth model for a Zn-air battery was established based on electrochemical phase field theory,and the effects of the charging time,anisotropy strength,and electrolyte temperature on the morphology and growth height of Zn dendrites were studied.A series of experiments was designed with different gradient influencing factors in subsequent experiments to verify the theoretical simulations,including elevated electrolyte temperatures,flowing electrolytes,and pulsed *** simulation results show that the growth of Zn dendrites is controlled mainly by diffusion and mass transfer processes,whereas the electrolyte temperature,flow rate,and interfacial energy anisotropy intensity are the main *** experimental results show that an optimal electrolyte temperature of 343.15 K,an optimal electrolyte flow rate of 40 ml·min^(-1),and an effective pulse charging mode.

关键词： Zn-air battery Zinc anode Zinc dendrite Simulated dendrite growth Inhibit dendrite growth Phase-field model