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ASME 2024 power Conference, power 2024

作者： Chen, Chen Liu, Ming Wang, Chaoyang Zhao, Yongliang Yan, Hui Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791888186

With the increasing penetration of renewable power, flexible power sources are urgently required by the power grid to balance the supply and demand sides. Therefore, the operational flexibility of subcritical coal-fired power plants should be further enhanced. In this study, dynamic models of a reference 330MW subcritical coal-fired power plant were developed and validated. The load ramp performances of the reference plant were simulated. The maximum ramp rates during loading down processes were 2%Pe/min and 1.5%Pe/min in 75% -50% and 50% -40% load cycling ranges, respectively, and the maximum ramp rate during loading up processes is 1.5%Pe/min. That the live steam and reheat steam temperatures exceeding their thresholds limits for the load ramp rates. The subcritical power unit has a steam drum, serving as a substance and energy storage device, and allows partial decoupling of feedwater flow and coal flow. Consequently, an enhanced steam temperature control strategy, facilitated by adjusting the feedwater flow rate during the load ramp processes, was proposed. The feedwater flow rate is appropriately regulated during load cycling dynamic processes to assist the control of live steam and reheat steam temperatures. The models to obtain the live steam and reheat steam temperature variations influenced by the feedwater flow rates are developed, and implemented in the control strategy. Then, simulations on the reference power plant with the enhanced control strategy were conducted, and the temperature overshoots have been effectively suppressed. As a result, the load ramp rate is increased. For example, in the load cycling range of 75%-40%, the overall unit ramp rate is increased by 1%Pe/min, achieving an enhancement in the operational flexibility of subcritical units. Copyright © 2024 by ASME.

关键词： Coal

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STRESS ANALYSIS AND LIFE ASSESSMENT OF THE STEAM TURBINE ROTOR DURING PEAK SHAVING TRANSIENT PROCESSES

STRESS ANALYSIS AND LIFE ASSESSMENT OF THE STEAM TURBINE ROT...

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ASME 2024 power Conference, power 2024

作者： Fan, Mengyang Zhao, Yongliang Liu, Ming Wang, Chaoyang Wang, Zhu Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

ISBN: (纸本)9780791888186

To achieve the net-zero emissions targets, the global share of renewable energy is rapidly increasing. The high penetration of intermittent and variable renewable power necessitates that coal-fired power plants enhance their operational flexibility for peak shaving and frequency regulation. Frequent and rapid start-ups, shutdowns, and peak shaving processes pose significant safety challenges to the steam turbine rotors. This paper investigates the impact of flexible operation on rotor stress. Firstly, an online monitoring model was developed and verified using a finite element model of a steam turbine high-medium pressure rotor. Secondly, the online calculation model was integrated with a dynamic coal-fired unit model developed using the JTopmeret software on the GSE platform, a well-established dynamic simulation tool for nuclear and fossil fuel power plants. Finally, a rotor low-cycle fatigue life assessment model was developed, and the von Mises stress and fatigue life loss under various load variation rates and ranges were determined. As the load variation rate increases, the life loss increases significantly, with maximum von Mises stress amplitudes of 5.2, 6.5 and 7.8 MPa at 1%, 2% and 3% Pe min−1 load variation rates, respectively. Conversely, as the load variation range increases, the life loss decreases substantially, with maximum von Mises stress amplitudes of 9.2 and 5.0 MPa during load variation processes of 50%-75% and 75%-100% THA, respectively. This study provides detailed guidance for optimizing the safe operation and control strategies of coal-fired power plants. Copyright © 2024 by ASME.

关键词： Steam turbines

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NUMERICAL SIMULATION OF FLUID-STRUCTURE COUPLING FOR THE MAIN PUMP OF LEAD COOLED FAST REACTOR 30

NUMERICAL SIMULATION OF FLUID-STRUCTURE COUPLING FOR THE MAI...

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30th International Conference on Nuclear engineering, ICONE 2023

作者： Xiang, Zutao Li, Liangxing Zhao, Jiayuan Xu, Xiangyang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9784888982566

The main pump blades of lead cooled fast reactor have complex mechanical characteristics, and there are complex fluid-structure coupling problems in the structural analysis of the impeller. In this paper, CFX software is mainly used for numerical simulation to carry out one-way fluid-structure coupling research on the moving blade of the main pump. Generally, three kinds of materials as Ti3SiC2, T91 steel and 304 stainless steel are considered for the moving blade of main pump and the deformation distribution and equivalent stress distribution of the three models under the three moving blade materials are analyzed respectively. Finally, the modal analysis of the moving blade of the main pump is carried out. The results show that the resistance to deformation of moving blade made in Ti3SiC2 is better than those of T91 steel and 304 stainless steel;The equivalent stress on the pressure surface of Ti3SiC2 is slightly higher than those of T91 steel and 304 stainless steel, and the maximum equivalent stress on the pressure surface of moving blade occurs on the inner edge of the blade. This research can provide reference for the design of moving blades, and help to improve the service life of the main pump. © 2023 by JSME.

关键词： Numerical models

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Study on factors of combustion characteristics of coals with thermo-balance

Study on factors of combustion characteristics of coals with...

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International Conference on power engineering 2013, ICOPE 2013

作者： Fu, Jiapeng Luo, Qinlan Chang, Yan Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 China

With the experimental system of thermo-balance, the combustion characteristics of powders of different kinds of coals under various experimental conditions are studied by using the method of thermo-gravimetric analysis and differential scanning calorimetry. Different factors such as heating rate, particle size and additives on the combustion characteristics are investigated. The results show that, with the raise of heating rate , coal combustion TG and DTG curves of different kinds of coal move to higher temperature zone and the combustion rate increases while the characteristics of ignition and burnout is strengthened. With the sample weight increasing, the ignition temperature and coal combustion rate decreases and the burnout temperature increases. With the decrease of particle size of coal powder, combustion characteristics are commonly enhanced firstly and wakened later. Additives such as K2CO3, Ca(OH)2, Fe(NO3)3·9H2O, FeSO4 can promote coal combustion in the low temperature zone(573∼723K).

关键词： Heating rate

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Measurement of laminar burning velocities and Markstein lengths for diethyl ether-air mixtures at different initial pressure and temperature 7

Measurement of laminar burning velocities and Markstein leng...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Di, Yage Huang, Zuohua Zhang, Ni Gu, Xiaolei Zheng, Bin Zhang, Zhiyuan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

Measurement of laminar burning velocities and Markstein lengths were made for the diethyl ether-air mixtures at different equivalence ratios, initial temperatures and pressures by using spherically propagating flame and schlieren photography method. The results show that the stretched flame propagation speeds and unstretched laminar burning velocities are increasing with the increase of the initial temperature. While the Markstein lengths are decreased with the increase of the initial temperature. The stretched flame propagation speeds, the unstretched laminar burning velocities and Markstein lengths are decreased with the increase of the initial pressure. The Markstein lengths are decreased with the increase of the equivalence ratio. Based on the experimental data, a correlation is obtained for the unstretched laminar burning velocity versus the initial temperature and pressure over wide range of equivalence ratios. © 2009 Combustion Institute. All rights reserved.

关键词： Mixtures

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Combustion characteristics and particulate emission in a natural-gas direct-injection engine: Effects of the injection timing and the spark timing

Combustion characteristics and particulate emission in a nat...

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作者： Liu, Y.-F. Liu, B. Liu, L. Zeng, K. Huang, Z.-H. State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an China

In the present study, the effects of injection timing and spark timing on combustion characteristics and particle emission were investigated. The particulate number concentration and size distribution were measured using an electrical low-pressure impactor. The combustion parameters were calculated from the cylinder pressure data. The results indicate that the combustion versus the injection timing is primarily dependent on the mixing quality of the air-fuel mixture. The particulate number concentration increases as the fuel injection is advanced but the particle size distribution is not affected significantly with different injection timings. This is probably related to the in-cylinder combustion. The initial combustion duration increases as the spark timing is advanced and the fastest rapid combustion duration is obtained at the maximum brake torque spark timing. As the fuel injection timing and spark timing are advanced, the particle number levels are increased but the particle size distribution shows few variations. Most of the particulates are in the nanoparticle size range. The amounts of nitrogen oxide and hydrocarbon emissions increase with advanced fuel injection timing and spark timing, and the carbon monoxide concentration experiences small variations under all operation conditions.

关键词： Time measurement

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Numerical simukation of nitrogen condensation flow in acryogeni nozzle 24

Numerical simukation of nitrogen condensation flow in acryog...

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24th IIR International Congress of Refrigeration, ICR 2015

作者： Wan, Sun Guoqing, Liu Lu, Niu Shuangtao, Chen Yu, Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 China

ISBN: (纸本)9782362150128

2-D numerical simulations on the nitrogen expansion flow with spontaneous condensation in a nozzle were conducted based on the equilibrium model and the non-equilibrium model respectively. In the equilibrium model, the mass transfer between the liquid and vapor is determined by the saturation enthalpies of the liquid and vapor phases. The pressure distribution of the nozzle could be influenced slightly by the condensation process. In the non-equilibrium model, the classical nucleation model is used for the droplets formation. The flow is heated by the latent heat and consequently the decrease of pressure and the increase of Mach number are delayed. Meanwhile, due to the requirement of a certain supercooling level, the condensation onset point is pushed away from the nozzle inlet, and the nozzle outlet wetness fraction becomes smaller. Then, the influence of the nozzle inlet temperature and inlet pressure on gas supercooling, nucleation rate and wetness are analyzed.

关键词： Nucleation

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Design and simulation of a novel geothermalsolar combined chimney power plant

Design and simulation of a novel geothermalsolar combined ch...

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26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013

作者： Cao, Fei Ma, Qiuming Zhao, Liang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

The solar chimney power plant (SCPP) is dominated by the solar radiation, and therefore its discontinuous operation is an unavoidable problem. In this paper, low temperature geothermal energy is introduced into the SCPP for overcoming this problem. Based on a developed mathematical model, theoretical analyses are carried out to investigate the performance of the geothermal-solar chimney power plant (GSCPP) with main dimensions the same as the Manzanares prototype in Spain. It is found that the GSCPP can attractively run in the full geothermal mode to deliver power continuously, which could solve the problem of the SCPP's running without sunlight in a long time, including at night. In addition, the introducing of geothermal energy into the SCPP can highly improve its power capacity.

关键词： Geothermal energy

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Manipulating metal-oxygen local atomic structures in singlejunctional p-Si/WO_(3) photocathodes for efficient solar hydrogen generation

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Nano Research 2021年第7期14卷 2285-2293页

作者： Wu Zhou Chung-Li Dong Yiqing Wang Yu-Cheng Huang Lingyun He Han-Wei Chang Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityShaanxi 710049China Department of Physics Tamkang UniversityTamsui 25137TaiwanChina

Self-passivation in aqueous solution and sluggish surface reaction kinetics significantly limit the photoelectrochemical(PEC)performances of silicon-based ***,a WO_(3) thin layer is deposited on the p-Si substrate by pulsed laser deposition(PLD),acting as a photocathode for PEC hydrogen *** to bare p-Si,the single-junctional p-Si/WO_(3) photoelectrodes exhibit excellent and stable PEC performances with significantly increased cathodic photocurrent density and exceptional anodic shift in onset potential for water *** is revealed that the WO_(3) layer could reduce the charge transfer resistance across the electrode/electrolyte interface by eliminating the effect of Fermi level pinning on the surface of *** importantly,by varying the oxygen pressures during PLD,the collaborative modulation of W–O bond covalency and WO6 octahedral structure symmetry contributes to the promoted charge carrier transport and ***,a large band bending at the p-Si/WO_(3) junction,induced by the optimized O vacancy contents in WO_(3),could provide a photovoltage as high as~500 mV to efficiently drive charge transfer to overcome the water reduction ***,by manipulating W–O local atomic structures in the deposited WO_(3) layer,a great improvement in PEC performance could be achieved over the singlejunctional p-Si/WO_(3) photocathodes for solar hydrogen generation.

关键词： silicon local atomic structure water splitting photocathodes hydrogen generation

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A calculation method for evaluating thermal loss of solar cavity receiver

A calculation method for evaluating thermal loss of solar ca...

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2009 Asia-Pacific power and Energy engineering Conference, APPEEC 2009

作者： Jiabin, Fang Jinjia, Wei Xunwei, Dong Yueshe, Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9781424424870

One of the most important components of solar thermal power system is the solar central receiver, which performance is in direct relation to the efficiency of the whole power generation system. The calculation of internal surface heat flux and thermal efficiency of receiver therefore plays a very important role in receiver design. A calculation method of heat loass of a cavity receiver is put forward in this paper. The first step of this method is to use the Monte Carlo method to simulate the track of solar beam and compute surface heat flux inside the receiver. The second step is to employ the correlations of flow boiling heat transfer to figure out the convective heat transfer coefficient inside the tubes and then the wall temperature of the boiling tubes laid inside the receiver. The last step is to simulate the air flow field inside the receiver to calculate convective thermal loss of the receiver. As every step can not be independently done, all steps are coupled and an iterative scheme is needed. Internal surface heat flux and thermal efficiency of the receiver can be finally gained with this method, and the result can provide theoretical guide for receiver design. © 2009 IEEE.

关键词： Monte Carlo methods

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