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Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

Nuclear Science and Techniques 2009年第2期20卷 118-123页

作者： TIAN Wenxi SU Guanghui WANG Gaopeng QIU Suizheng XIAO Zejun State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi＇an Jiaotong University Xi＇an 710049 China National Key Laboratory of Bubble Physics ＆ Natural Circulation Nuclear Power Institute of China Chengdu 610041 China

The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup *** motion of check valve disc was simulated using inertial valve *** parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc *** been *** results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel *** induced maximum pressure vibration amplitude is up to 5.0 *** scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water *** has been numerically approved to be an effective approach.

关键词：止回阀建设部事件水锤泵给水系统启动过程压力振动瞬态参数

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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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Functional expression of proton pumps in Rhodobacter sphaeroides enhanced energy supply and photo-fermentative hydrogen production

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Bioresource Technology 2025年 432卷

作者： Xuefang Mu Yuntong Xu Yu Ma Zixuan Gao Jiali Feng Minmin Wang Wen Cao Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xianning West Rood Xi’an 710049 PR China College of Biology and Oceanography Weifang University Weifang 261061 Shandong PR China

Photo-fermentative hydrogen production by Rhodobacter sphaeroides ( R. sphaeroides ) is an energy-consuming process. In this study, a proton-pumping channel (Proteorhodopsin (PR) or Gloeobacter rhodopsin (GR)) was introduced into R. sphaeroides HY01. The results indicated that PR could enhance the biomass of the strain during periods of resource scarcity. The cumulative hydrogen yield of mutant strains (HY01-PR and HY01-GR) increased by 66 % and 75 % compared with HY01 when glucose was fed, respectively. Notably, HY01-GR demonstrated tolerance to high acetate concentrations (93 mM). Moreover, the introduction of proton-pump resulted in a reduction of catabolism carbon flow and the accumulation of various metabolites. This study also confirmed that proton pump overexpression generated more ATP in the late stages of fermentation by coupling ATP synthase. Overall, these findings suggest that proton pumps could potentially be applied to photosynthetic organisms to regulate growth metabolism and enhance the production of valuable compounds.

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THE FLEXIBILITY ENHANCEMENT OF SUBCRITICAL COAL-FIRED power PLANTS: CONTROL STRATEGY OPTIMIZATION FOR LIVE AND REHEAT STEAM TEMPERATURE

THE FLEXIBILITY ENHANCEMENT OF SUBCRITICAL COAL-FIRED POWER ...

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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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Study on iterative algorithm of full plate cross-flow and counter-flow printed circuit heat exchanger for fluoride-salt-cooled high-temperature advanced reactor

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International Journal of Advanced Nuclear Reactor Design and Technology 2023年第2期5卷 86-96页

作者： Li, Xinze Zhang, Dalin Li, Xinyu Tian, Wenxi Qiu, Suizheng Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

In the concept of Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR), the Printed Circuit Heat Exchanger (PCHE) is mainly considered in its supercritical carbon dioxide (S–CO2) Brayton cycle secondary loop. The design of the PCHE is based on the property of working fluid provided by the Brayton cycle system design. Therefore, a fast and iterative PCHE design method is required. In this study, a mathematical model based on Picard's iterative method is proposed. The model can solve full plate temperature field with complex boundary conditions and initial values including cross-flow and counter-flow PCHE in parallel. Based on FuSTAR Brayton cycle design conditions, three sizes of cross-flow and counter-flow PCHEs are simulated respectively by the mathematical model. Compared with Computational Fluid Dynamics (CFD) models, a one and three-dimensional coupling model and a three-dimensional model, the mathematical model reduced the computing time from 1 to 10 h to 1–10 s, and the maximum temperature mean deviation is 18.6% for the smallest size case because of the edge effect and local disturbance, but 8.4% for other size. Taking secondary loop recuperator design as example, the computing speed and accuracy of the mathematical model can meet the design requirements of FuSTAR PCHE. © 2023 Xi'an Jiaotong University

关键词： Carbon dioxide

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Optimization of the concentration field in a suspended photocatalytic reactor with the periodically changing solar irradiation

Optimization of the concentration field in a suspended photo...

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

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

Feasibility of the solar photocatalysis has been validated theoretically and experimentally. Main concerns on the solar photocatalysis in the solutions are: the mass transfer limitation between the photocatalyst and the solution, and the concentration or radiation distribution in the photoreactors. Most researches concentrated their research on one aspect. There is limited research considering variable catalysis concentrations together with the changing solar radiation. However, outdoor solar photocatalysis devices, i.e. for hydrogen production or waste water degradation, would practically face this phenomenon. In the present study, the photon absorption in a suspended photocatalytic reactor was simulated by adopting Monte Carlo method and the six-flux radiation absorption-scattering model. Different photocatalyst concentrations were taken into account. Simulation results indicated that the photon absorption had a close relationship with the concentration distribution of the photocatalysts, and that there is an optimal concentration gradient in the photoreactor leading to the maximum photon absorption. Accordingly, the concentration field is optimized according to the changing solar irradiation. The present work is expected to be of effective value for obtaining the optimal operating parameters for industrial solar photocatalytic applications.

关键词： Solar radiation

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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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state-of-the-art progress in overall water splitting of carbon nitride based photocatalysts

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Frontiers in Energy 2021年第3期15卷 600-620页

作者： Bing LUO Yuxin ZHAO Dengwei JING School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Converting solar energy into hydrogen(H_(2))by photocatalytic water splitting is a promising approach to simultaneously address the increasing energy demand and environmental *** decade has passed since the discovery of photo-induced water splitting phenomenon on TiO_(2)photoanode,while the solar to H_(2) efficiency is still around 1%,far below the least industrial ***,developing efficient photocatalyst with a high energy conversion efficiency is still one of the main tasks to be *** carbon nitride(g-C_(3)N_(4))is just such an emerging and potential ***,in this review,the state-of-the-art advances in g-C_(3)N_(4)based photocatalysts for overall water splitting were summarized in three sections according to the strategies used,and future challenges and new directions were discussed.

关键词： photocatalysis overall water splitting carbon nitride hydrogen

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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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Preliminary study on FROBA-SCO2 with transient models and its application for Reactivity Initiated Accident and loss of flow accident

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International Journal of Advanced Nuclear Reactor Design and Technology 2022年第3期4卷 101-108页

作者： Yang, T.A. Zhang, K. Yang, H.K. Tian, W.X. Qiu, S.Z. School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

As a coolant enabling the reactor with a high efficiency and low volume, the supercritical CO2 has becoming a hot topic nowadays. However, the fuel rod behaviors under accidents are not studied thoroughly, especially the interaction between the coolant and the cladding. With the previous study of fuel rod behaviors analysis of supercritical CO2 cooled nuclear reactor under steady state operation, transient state models are implemented and the upgraded code can be used to predict the fuel rod behaviors under RIA and LOFA. After the comparation of the calculation results with SACOS-SCO2, the tendency and numerical value are close, so the accuracy is warranted. The upgraded FROBA-SCO2 is used to predict the fuel rod behaviors under RIA and LOFA conditions and the results indicate that the maximum temperature of cladding and fuel is within safety limits. © 2022

关键词： Coolants

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