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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

Insight into the selective separation of CO_(2)from biomass pyrolysis gas over metal-incorporated nitrogen-doped carbon materials:a first-principles study

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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

Dynamic Modeling of Key Operating Parameters for Supercritical Circulating Fluidized Bed Units based on Data-Knowledge-Driven Method

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Journal of Thermal Science 2024年第3期33卷 1216-1230页

作者： YU Haoyang GAO Mingming ZHANG Hongfu CHEN Jiyu LIU Jizhen YUE Guangxi The State Key Laboratory of Alternate Electrical power System with Renewable energy Sources School of Control and Computer EngineeringNorth China Electric Power UniversityBeijing102206China CHN energy New energy Technology Research Institute Co. Ltd.Beijing102209China Department of energy and power Engineering Tsinghua UniversityBeijing100084China

To address the pressing need for intelligent and efficient control of circulating fluidized bed(CFB)units,it is crucial to develop a dynamic model for the key operating parameters of supercritical circulating fluidized bed(SCFB)***,data-knowledge-driven dynamic model of bed temperature,load,and main steam pressure of the SCFB unit has been ***,a knowledge-driven method is employed to develop a dynamic model for key operating parameters of SCFB *** model parameters are determined based on the operating data of the unit and continuously optimized in real ***,Bidirectional Long Short-Term Memory combined with Convolutional Neural Network and Attention Mechanism is utilized to build the dynamic model of bed temperature,load,and main steam ***,a collaboration and integration method based on the critic weight method and the variation coefficient method is proposed to establish data-knowledge-driven model of key operating parameters for SCFB *** model displays great accuracy and fitting ability compared with other methods and effectively captures the dynamic characteristics,which can provide a research basis for the design of intelligent flexible control mode of SCFB unit.

关键词： circulating fluidized bed dynamic model data-knowledge-driven method deep learning power plant

Assessment and Enhancement of FRC of power Systems Considering Thermal power Dynamic Conditions

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CSEE Journal of power and energy Systems 2024年第4期10卷 1371-1383页

作者： Feng Hong Yalei Pang Weiming Ji Lu Liang Fang Fang Junhong Hao Jizhen Liu State Key Laboratory of Alternate Electric power System with Renewable energy Sources and School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Alternate Electric power System with Renewable energy Sources School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China

Frequency stability and security have been a vital challenge as large-scale renewable energy is integrated into power *** contrast,the proportion of traditional thermal power units decreases during the decarbonization transformation process,resulting in poor frequency *** paper aims to explore the potential of frequency regulation support,dynamic assessment,and capacity promotion of thermal power plants in the transition *** the dynamic characteristics of the main steam working fluid under different working conditions,a nonlinear observer is constructed by extracting the main steam pressure and valve opening degree *** real-time frequency modulation capacity of thermal power units can provide a dynamic state for the power grid.A dynamic adaptive modification for primary frequency control(PFC)of power systems,including wind power and thermal power,is proposed and *** power dynamic allocation factor is adaptively optimized by predicting the speed droop ratio,and the frequency modulation capability of the system is improved by more than 11%under extreme ***,through the Monte Carlo simulation of unit states of the system under various working conditions,the promotion of the frequency regulation capacity with high wind power penetration(WPP)is verified.

关键词： Dynamic evaluation frequency regulation power system predictive modeling wind penetration

Multi-Objective Multi-Variable Large-Size Fan Aerodynamic Optimization by Using Multi-Model Ensemble Optimization Algorithm

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Journal of Thermal Science 2024年第3期33卷 914-930页

作者： XIONG Jin GUO Penghua LI Jingyin School of energy and power Engineering Xi’an Jiaotong UniversityXi’an710049China

The constrained multi-objective multi-variable optimization of fans usually needs a great deal of computational fluid dynamics(CFD)calculations and is *** this study,a new multi-model ensemble optimization algorithm is proposed to tackle such an expensive optimization *** multi-variable and multi-objective optimization are conducted with a new flexible multi-objective infill *** addition,the search direction is determined by the multi-model ensemble assisted evolutionary algorithm and the feature extraction by the principal component analysis is used to reduce the dimension of optimization ***,the proposed algorithm and other two optimization algorithms which prevail in fan optimizations were compared by using test *** the same number of objective function evaluations,the proposed algorithm shows a fast convergency rate on finding the optimal objective function ***,this algorithm was used to optimize the rotor and stator blades of a large axial fan,with the efficiencies as the objectives at three flow rates,the high,the design and the low flow ***-two variables were included in the optimization *** results show that compared with the prototype fan,the total pressure efficiencies of the optimized fan at the high,the design and the low flow rate were increased by 3.35%,3.07%and 2.89%,respectively,after CFD simulations for 500 fan candidates with the constraint for the design *** optimization results validate the effectiveness and feasibility of the proposed algorithm.

关键词： multi-objective optimization surrogate-assisted evolutionary algorithm axial fan computational fluid dynamics aerodynamic optimization

An Overview of Sequential Approximation in Topology Optimization of Continuum Structure

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 43-67页

作者： Kai Long Ayesha Saeed Jinhua Zhang Yara Diaeldin Feiyu Lu Tao Tao Yuhua Li Pengwen Sun Jinshun Yan State Key Laboratory of Alternate Electrical power Systemwith Renewable energy Sources North China Electric Power UniversityBeijing102206China Faculty of Materials and Manufacturing Beijing University of TechnologyBeijing100124China New energy and energy Storage division China Southern Power Grid Technology Co.Ltd.Guangzhou510080China School of Mechanical Engineering Inner Mongolia University of TechnologyHohhot010051China College of energy and power Engineering Inner Mongolia University of TechnologyHohhot010051China

This paper offers an extensive overview of the utilization of sequential approximate optimization approaches in the context of numerically simulated large-scale continuum *** structures,commonly encountered in engineering applications,often involve complex objective and constraint functions that cannot be readily expressed as explicit functions of the design *** a result,sequential approximation techniques have emerged as the preferred strategy for addressing a wide array of topology optimization *** the past several decades,topology optimization methods have been advanced remarkably and successfully applied to solve engineering problems incorporating diverse physical *** comparison to the large-scale equation solution,sensitivity analysis,graphics post-processing,etc.,the progress of the sequential approximation functions and their corresponding optimizersmake sluggish ***,particularly novices,pay special attention to their difficulties with a particular ***,this paper provides an overview of sequential approximation functions,related literature on topology optimization methods,and their *** from optimality criteria and sequential linear programming,the other sequential approximate optimizations are introduced by employing Taylor expansion and intervening *** addition,recent advancements have led to the emergence of approaches such as Augmented Lagrange,sequential approximate integer,and non-gradient approximation are also *** highlighting real-world applications and case studies,the paper not only demonstrates the practical relevance of these methods but also underscores the need for continued exploration in this ***,to provide a comprehensive overview,this paper offers several novel developments that aim to illuminate potential directions for future research.

关键词： Topology optimization sequential approximate optimization convex linearization method ofmoving asymptotes sequential quadratic programming

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

Nanostructured AlFeO_(3) thin films as a novel photoanode for photoelectrochemical water splitting

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Nano Research 2024年第3期17卷 1075-1085页

作者： Xin Sun Min Wang Qi Geng Shuailin Chen Xiaojun Lv Xunlei Ding Meicheng Li State Key Laboratory of Alternate Electrical power System with Renewable energy Sources School of New EnergyNorth China Electric Power UniversityBeijing 102206China School of Mathematics and Physics North China Electric Power UniversityBeijing 102206China

The earth-abundant and robust aluminum ferrite,AlFeO_(3)(AFO),is mainly studied in the context of ***,we demonstrate that AFO can be used as a stable solar absorber in photoelectrochemical cells for solar water splitting,exhibiting attractive *** is the first report on the photoelectrochemical activity of *** thin-film photoelectrodes prepared by solution-processing methods are composed of vertically oriented thin nanosheets,featuring the rhombohedral symmetry(R3c)and n-type *** as-prepared AFO photoanodes generate a photocurrent density of+0.78 mA·cm^(-2) at 1.23 V *** hydrogen electrode(RHE)with the photocurrent _(onset) potential(U_(onset))close to the flat band potential of 0.5 V *** in the presence of hole ***,the U_(onset) of AFO for solar water splitting coincides with the flat band potential as well,which is rare in n-type inorganic *** also report other properties of AFO associated with photoelectrochemical *** films exhibit a band gap energy of 2.31 eV and positive band edges with low ***,the carrier lifetimes in AFO films are up to millisecond timescales under the mediation of defect *** on the photoelectrochemical behavior and optoelectronic properties,we believe that AFO has great potential for application in photoelectrochemical cells.

关键词： AlFeO_(3) photoanode nanosheets photoelectrochemistry onset potential

Crystallization management of CsPbI_(2)Br perovskites by PbAc_(2)-incorporated twice spin-coating process for efficient and stable CsPbI_(2)Br perovskite solar cells

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Journal of energy Chemistry 2024年第10期97卷 419-428,I0008页

作者： Yu Liu Kun Lang Huifang Han Huijing Liu Yao Fu Pengchen Zou Yinhui Lyu Jia Xu Jianxi Yao State Key Laboratory of Alternate Electrical power System with Renewable energy Sources Beijing Key Laboratory of Energy Safety and Clean UtilizationNorth China Electric Power UniversityBeijing 102206China

CsPbI_(2)Br perovskite solar cell has been extensively studied due to its exceptional thermal stability and relatively stable perovskite phase ***,the presence of bromine leads to a rapid crystallization rate of CsPbI_(2)Br films,resulting in small grain size and high defect ***,CsPbI_(2)Br demonstrates poor light absorption due to its wide ***,it is crucial to control the crystallization rate and increase the film thickness to reduce defect density,enhance light absorption,and improve photovoltaic *** this study,we utilized a PbAc_(2)-incorporated twice spincoating(PTS) process to address these ***,PbAc_(2) was added to the CsPbI_(2)Br precursor solution to form a CsPbI_(2)Br film,which was then coated with the CsPbI_(2)Br precursor solution to produce the PTS film,Ac^(-)can delay the perovskite crystallization,leading to the formation of thicker and denser CsPbI_(2)Br ***,lone-pair electrons of the oxygen atom provided by Ac^(-)formed coordination bonds with under-coordinated Pb~(2+) ions to fill halogen ion vacancies,thereby reducing the defect ***,the PTS CsPbI_(2)Br device achieved a peak power conversion efficiency(PCE) of 16.19% and maintained 96.7% of its initial PCE over 1500 h at room temperature under 25% relative humidity without any encapsulation.

关键词： CsPbI_(2)Br Twice spin-coating process PbAc_(2) Crystallization management Perovskite solar cells