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ASME 2024 Power Conference, POWER 2024

作者： Liu, Zefeng Wang, Chaoyang Liu, Ming Yan, Junjie State Key Laboratory of Multiphase Flow Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791888186

Switching between wet and dry states occurs frequently when the ultra-supercritical coal-fired power plant operates between 15% and 30% rated load. How to keep wet-state operation stable and switching between wet and dry states rapidly becomes an increasing concern. This study established a detailed dynamic model of a 660MW ultra-supercritical coal-fired power plant, including the boiler recirculation system in low-load. During the state conversion process, the boiler components' safe operation limitations were also considered as boundary conditions. Based on the developed model, the change trends of the key parameters were simulated when the wet-state operation and the energy distribution characteristics were analyzed during the conversion process. The results show that the temperature of separated recirculation water is greater than that of feedwater before converging, which has great potential to shorten the conversion time. The control scheme of recirculation water was revised by reconstructing the curve between the water level of the separator storage tank and the opening of the recirculation valve. The subcooling degree of feedwater entering the water wall decreased by regulating the recirculation of separated water on time and reasonably. The duration required for saturation decreased considerably with a constant water flow rate. By implementing the optimized control scheme, the operating mode switches from wet to dry in advance, and the corresponding unit load can decrease from 24.5% to 23.1% rated load. Based on the boiler components' safe operation, the state-conversion time can be shortened by 30% at most. This research will guide the low-load flexibility and safe operation optimization. Copyright © 2024 by ASME.

关键词： Fossil fuel power plants

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Uncertainty and sensitivity analysis of in-vessel phenomena under severe accident mitigation strategy based on ISAA-SAUP program

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Nuclear Science and Techniques 2024年第1期35卷 108-123页

作者： Hao Yang Ji-Shen Li Zhi-Ran Zhang Bin Zhang Jian-Qiang Shan School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The phenomenology involved in severe accidents in nuclear reactors is highly ***,integrated analysis programs used for severe accident analysis heavily rely on custom empirical parameters,which introduce considerable ***,in recent years,the field of severe accidents has shifted its focus toward applying uncertainty analysis methods to quantify uncertainty in safety assessment programs,known as“best estimate plus uncertainty(BEPU).”This approach aids in enhancing our comprehension of these programs and their further development and *** study concentrates on a third-generation pressurized water reactor equipped with advanced active and passive mitigation *** an Integrated Severe Accident Analysis Program(ISAA),numerical modeling and uncertainty analysis were conducted on severe accidents resulting from large break loss of coolant *** uncertainty parameters of the ISAA program were meticulously *** Wilks'formula,the developed uncertainty program code,SAUP,was employed to carry out Latin hypercube sampling,while ISAA was employed to execute batch *** analysis was then conducted on two figures of merit,namely hydrogen generation and the release of fission products within the pressure *** calculations revealed that hydrogen production and the fraction of fission product released exhibited a normal distribution,ranging from 182.784 to 330.664 kg and from 15.6 to 84.3%,*** ratio of hydrogen production to reactor thermal power fell within the range of 0.0578–0.105.A sensitivity analysis was performed for uncertain input parameters,revealing significant correlations between the failure temperature of the cladding oxide layer,maximum melt flow rate,size of the particulate debris,and porosity of the debris with both hydrogen generation and the release of fission products.

关键词： Gen-III PWR Severe accident mitigation Wilks’formula Hydrogen Fission products Uncertainty and sensitivity analysis

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Synergistic effect of oxygen species and vacancy for enhanced electrochemical CO_(2) conversion to formate on indium oxide

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eScience 2024年第3期4卷 134-141页

作者： Tengfei Ma Zihao Jiao Haoran Qiu Feng Wang Ya Liu Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Indium-based oxides are promising electrocatalysts for producing formate via CO_(2) reduction reaction,in which*OCHO is considered the key ***,we identified that the*COOH pathway could be preferential to produce formate on In_(2)O_(3)of In/In_(2)O_(3) heterojunction due to the synergistic effect of oxygen species and ***,*CO_(2) and *COOH were observed on In_(2)O_(3) and related to formate production by in situ Raman *** theoretical calculations further demonstrated that the energy barrier of the*COOH formation on In_(2)O_(3) was decreased in the presence of oxygen vacancy,similar to or lower than that of the*OCHO formation on the In *** a result,a formate selectivity of over 90%was obtained on prepared In/In_(2)O_(3) heterojunction with 343±7mAcm^(-2) partial current ***,when using a Si-based photovoltaic as an energy supplier,10.11%solar-to-fuel energy efficiency was achieved.

关键词： Electrocatalytic CO_(2)reduction Formate In_(2)O_(3) Oxygen species Oxygen vacancy

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Development of a fan-stirred constant volume combustion chamber and turbulence measurement with PIV

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Frontiers in Energy 2022年第6期16卷 973-987页

作者： Haoran ZHAO Jinhua WANG Xiao CAI Zhijian BIAN Hongchao DAI Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

A fan-stirred combustion chamber is developed for spherically expanding flames,with P and T up to 10 bar and 473 K,*** characteristics are estimated using particle image velocimetry(PIV)at different initial pressures(P=0.5-5 bar),fan frequencies(ω=0-2000 r/min),and impeller diameters(D=100 and 114 mm).The flame propagation of methanol/air is investigated at different turbulence intensities(u′=0-1.77 m/s)and equivalence ratios(f=0.7-1.5).The results show that u′is independent of P and proportional toω,which can be up to 3.5 m/s at 2000 r/min.L_(T)is independent of P and performs a power regression withω*** turbulent field is homogeneous and isotropic in the central region of the chamber while the inertial subrange of spatial energy spectrum is more collapsed to-5/3 law at a high Re_(T).Compared to laminar expanding flames,the morphology of turbulent expanding flames is wrinkled and the wrinkles will be finer with the growth of turbulence intensity,consistent with the decline of the Taylor scale and the Kolmogorov *** determined S_(L)in the present study is in good agreement with that of previous *** S_(L)and S_(T)of methanol/air have a non-monotonic trend with f while peak S_(T)is shifted to the richer side compared to S_(L).This indicates that the newly built turbulent combustion chamber is reliable for further experimental study.

关键词： fan-stirred combustion chamber turbulence characteristics particle image velocimetry(PIV) methanol turbulent expanding flames

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Numerical simulation of local and global mixing/segregation characteristics in a gas–solid fluidized bed

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Chinese Journal of Chemical Engineering 2022年第4期35卷 72-86页

作者： Zhen Wan Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Researches on solids mixing and segregation are of great significance for the operation and design of fluidized bed *** this paper,the local and global mixing and segregation characteristics of binary mixtures were investigated in a gas–solid fluidized bed by computational fluid dynamics-discrete element method(CFD-DEM)coupled approach.A methodology based on solids mixing entropy was developed to quantitatively calculate the mixing degree and time of the *** mixing curves of global mixing entropy were acquired,and the distribution maps of local mixing entropy and mixing time were also *** comparing different operating conditions,the effects of superficial gas velocity,particle density ratio and size ratio on mixing/segregation behavior were *** showed that for the partial mixing state,the fluidized bed can be divided into three parts along the bed height:complete segregation area,transition area and stable mixing *** areas showed different mixing/segregation *** gas velocity promoted the local and global mixing of binary *** increase in particle density ratio and size ratio enlarged the complete segregation area,reduced the mixing degree and increased the mixing time in the stable mixing area.

关键词： Discrete element method Solids mixing Binary mixtures Fluidized bed

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Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

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Particuology 2023年第6期77卷 128-135页

作者： Chao Zhang Zhichao Zhang Longxiang Bu Yang Yang Wei Xiong Yueshe Wang School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai200093China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol ***,knowledge on the morphology of surfactant particles after the adsorption of water is *** this study,the interaction between water and particles composed of surface active malonic acid(MA)or adipic acid(AA)are simulated based on the molecular dynamics *** key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium *** show that demixed structure 1 with the adsorption of water clusters on acid grain,mixed structure and demixed structure 2 with acids coating on water droplet can be *** temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then *** the standard atmospheric temperature(280-330 K),the surface propensity of MA and AA increases with increasing water content and alkyl group,and its sensitivity to temperature and water content varies ***,all surfactants at the particle surface orient their hydrophobic groups toward the *** findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

关键词： Aerosol particles Surfactant Surface propensity Hygroscopic growth Molecular dynamics

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Optimization of cold-end system of thermal power plants based on entropy generation minimization

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Frontiers in Energy 2022年第6期16卷 956-972页

作者： Yue FU Yongliang ZHAO Ming LIU Jinshi WANG Junjie YAN State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power *** enhance the efficiency of thermal power plants,multi-pressure condensers have been applied in some large-capacity thermal power ***,little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be ***,the design optimization methods of coldend systems with single-and multi-pressure condensers are developed based on the entropy generation rate,and the genetic algorithm(GA)is used to optimize multiple *** parameters,including heat transfer area of multi-pressure condensers,steam distribution in condensers,and cooling water mass flow rate,are optimized while considering detailed entropy generation rate of the cold-end *** results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is ***,the economic performance can be improved with the adoption of the multi-pressure cold-end *** compared with the single-pressure cold-end system,the excess revenues gained by using dual-and quadruplepressure cold-end systems are 575 and 580 k$/a,respectively.

关键词： cold-end system entropy generation minimization optimization economic analysis genetic algorithm(GA)

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Solar fuel production through concentrating light irradiation

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Green Energy & Environment 2024年第10期9卷 1550-1580页

作者： Yiwei Fu Yi Wang Jie Huang Kejian Lu Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase FlowXi'an Jiaotong UniversityXi'anShaanxi710049China Suzhou Academy of Xi'an Jiaotong University SuzhouJiangsu215123China

The climate crisis necessitates the development of non-fossil energy *** solar energy for fuel production shows promise and offers the potential to utilize existing energy ***,solar fuel production is in its early stages of development,constrained by low conversion efficiency and challenges in scaling up *** solar energy(CSE)technology has matured alongside the rapid growth of solar thermal power *** review provides an overview of current CSE methods and solar fuel production,analyzes their integration compatibility,and delves into the theoretical mechanisms by which CSE impacts solar energy conversion efficiency and product selectivity in the context of photo-electrochemistry,thermochemistry,and photo-thermal co-catalysis for solar fuel *** review also summarizes approaches to studying the photoelectric and photothermal effects of ***,it explores emerging novel CSE technology methods in the field of solar fuel production.

关键词： Concentrated solar energy Solar fuel Photo-electrochemistry Thermochemistry Photo-thermal co-catalysis

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Fluidization of particles in SCW fluidized bed:Voidage distribution of emulsion phase

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Particuology 2022年第4期20卷 60-75页

作者： Hao Wang Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

Supercritical water(SCW)fluidized bed reactors convert biomass to fuels without pollutants *** this work,experimental studies were carried out to investigate voidage distribution in an SCW fu-idized bed by capacitance *** sands with different particle sizes were fluidized by SCW under system pressure of 20-27 MPa and temperature of 410-570℃.The effect of operation conditions on voidage distributions of the emulsion phase(*** voidage and probability density)is discussed.A predicting correlation between voidage and superficial velocity in emulsion phase is *** relative error of the correlation is within+25%.These research results provide useful guidance for the optimization of supercritical water gasification technology.

关键词： Supercritical water fluidized bed Capacitance probe measurement system Voidage distribution

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THERMAL-HYDRAULIC ANALYSIS OF THE COOLING WALL IN ULTRA SUPERCRITICAL COAL-FIRED GENERATION PLANTS DURING DEEP PEAKING

THERMAL-HYDRAULIC ANALYSIS OF THE COOLING WALL IN ULTRA SUPE...

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ASME 2024 Power Conference, POWER 2024

作者： Wang, Dengliang Zhao, Yongliang Chen, Weixiong Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

ISBN: (纸本)9780791888186

Due to increasingly severe environmental and climate concerns currently, renewable energy is highly penetrated around the world. However, given the intermittency and instability of renewable energy, coal-fired generation plants urgently need to undertake deep peak shaving tasks, resulting in the frequent load cycling transient processes of units. It will have a significant effect on the safe operation of the boiler components, especially for the hydrodynamic instability of cooling wall within the boiler. This paper takes a 1100 MW ultra-supercritical primary reheat coal-fired generation plants as the research object. In accordance with the heating load distribution characteristics of cooling wall, a hydrodynamic characteristic calculation model of cooling wall within the boiler is constructed based on the mass conservation, momentum conservation and energy conservation equations, which introduces numerous empirical correlations available for heat transfer and hydraulic resistance calculation at the same time. The working fluid temperature in the direction of cooling wall height at 100% THA, 75% THA, 50% THA, 40% THA and 30% THA, as well as the metal temperature of the inner, outer and fin tube walls are analyzed. The changes in metal wall temperature of cooling wall under different load cycling rates are obtained during the low load operating range of 50% THA to 30% THA. Ultimate load cycling rates of the coal-fired generation plants without causing the overtemperature issue of cooling wall is obtained. Finally, when the revised fuel supply control strategy is adopted, it is able to significantly reduce the maximum metal wall temperature during the rapid load cycling process. The maximum load cycling rate is increased from 2.5% Pe/min to 3.0% Pe/min for the loading up process. Copyright © 2024 by ASME.

关键词： Coal

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