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SSRN 2023年

作者： Ge, Hui Huang, Yong Liu, Zhaozheng Liu, Fan Chen, Yu-Nan Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The hydrophilicity of lignocellulosic biomass hinders the application of a high concentration slurry for supercritical water gasification, thereby reducing the efficiency of gasification and energy self-sufficiency. A pretreatment method of alkaline pulping with KOH and NaOH was proposed considering initial pressure to prepare high concentration slurry. In this study, bark as lignocellulosic biomass specimen, whose 30wt% and 40wt% slurries, with favorable rheology and stability, was prepared via alkaline pulping successfully. The most economical conditions were 180 °C and 24% KOH addition. The bark macromolecules were restructured due to the hydrolysis of cellulose and lignin by breaking down the hydrogen bond and ether bond with trivial hydrocarbon matrix loss. The scattered crystal growth being created and a reduction of hydrophilic groups facilitated the uniform premixing of bark and water, which is improved by a stable charge system furtherly. Additionally, metal ions could be deposited onto the bark surface during alkaline pulping. The chemical modification leading by alkaline pulping achieved the premixing of feedstock and water to form bark slurry. The conversion barrier was decreased to fulfill the ordered conversion. Consequently, the commendable catalytic effect of 95.66% gasification efficiency was displayed for 40wt% bark slurry with trivial coke yield. The functional groups of organic matter in the slurry were significantly converted into the gas phase, and lattice oxygen was produced in the solid product. The maximum alkali recovery of 80% was achieved at 580 °C. The successful completion of this research affirms the dominance of the pulping-alkali recovery-gasification method for expanding the application of SCWG of lignocellulosic biomass in large engineering projects. © 2023, The Authors. All rights reserved.

关键词： Chemical modification

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Experimental and Numerical Study of Hydraulic Characteristics and Pressurization Deterioration Mechanism of a Three-Stage Mixed-flow Multiphase Pump Under Gas Liquid Condition

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SSRN 2023年

作者： Dai, Xiaoyu Xu, Qiang Yang, Chenyu Su, Xiaobin Chang, Liang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Shanghai Institute of Satellite Engineering Shanghai201109 China

The mixed-flow multiphase pump may experience pressurization deterioration due to the high Gas Volume Fraction, resulting in pressurization failure and posing a threat to the pressurization unit's safety. In this paper, a three-stage mixed-flow multiphase pump with closed impeller structure is designed and developed. The hydraulic characteristics and pressurization deterioration mechanism of the multiphase pump were investigated at various rotational speeds and inlet conditions using the experiment and simulation. As the liquid flow rate rises, the multiphase pump experiences a 'three-stage' downward trend in pressurization. The first booster stage has a greater capacity for pressurizing the liquid phase. The gas-liquid pressurization exhibits a wave-shaped downward trend due to significant deterioration in stage-wise pressurization when the liquid flow rate is low. Once the Inlet Gas Volume Fraction reaches the initial critical Gas Volume Fraction, the gas aggregates on the impeller’s suction surface is removed at the impeller outlet, creating an annular air mass. When this mass of air meets the fluid behind it, it creates a chaotic vortex that absorbs the fluids' kinetic energy. As a result, the first booster stage experiences a significant reduction in its pressurization ability, causing an abrupt decrease in the pressurization curve. © 2023, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Experimental and numerical investigation of two phase ejector performance with the water injected into the induced flow

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International Journal of Advanced Nuclear Reactor Design and Technology 2020年 2卷 15-24页

作者： Chen, WeiXiong Huang, ChenXi Bai, YuPing Chong, DaoTong Yan, JunJie Liu, JiPing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

When injectors are used in petroleum industries or sea water desalination system, it is a special case that the induced gas is accompanied by water, the ejector is in two-phase operation. In the present study, the ejector performance at two phase flow is investigated experimentally and numerically. The results indicate that: the entrainment ratio would decrease when the water is injected into the induced flow, as well as the pressure ratio. The maximum decrement of entrainment ratio is around 40.5% at sub-critical mode when the motive pressure is 1.0 MPa, the induced pressure is 0.2 MPa, liquid-air ratio is 22%. For the pressure ratio, the maximum decrement is 62.5% when the motive pressure is 1.0 MPa, the induced pressure is 0.5 MPa, liquid-air ratio is 2.87%. However, the lower the induced pressure is, the more obvious the effect of mass flow rate on entrainment rate is, while the effect on pressure ratio is just opposite. Moreover, the performance becomes worse in sub-critical mode than that in critical mode. The effect of NXP on ejector performance also has been analyzed. There exists an optimum NXP whether the two phase flow ejector is in critical mode or sub-critical mode. The optimum NXP for entrainment ratio enlarges from 3.6 mm to 4.4 mm with the increase of water mass flowrate, and is bigger than that of single phase ejector (the optimum NXP is 2.8 mm). This study may provide a beneficial reference for the operation of supersonic ejectors on two phase flow. © 2020 Xi'an Jiaotong University

关键词： Two phase flow

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Experimental investigation on heat transfer characteristics of high temperature air in round tube

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 200-205页

作者： Qin, Hao Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, Guanghui Department of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi'an710049 China Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi'an Jiaotong University China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

Air is widely utilized as working fluid in heat exchangers with high heat flux and high temperature, and the empirical correlations for predicting local and total heat transfer coefficients are indispensable for thermal design and optimization of the heat exchange applications. Experimental investigation on heat transfer characteristics of high temperature air in round tube is conducted. The experimental system is designed and constructed. The data processing method for obtaining wall temperature and heat transfer coefficient is introduced. The measured local and total heat transfer coefficients are compared with the widely adopted correlations, including Taylor's correlation and Gnielinski's correlation. The suggested empirical correlations obtained from the experimental data are presented, which may contribute to the design of heat exchangers concerning with high temperature air. © 2021 Xi'an Jiaotong University

关键词： Heat transfer coefficients

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Non-Hermitian Delocalization in a Two-Dimensional Photonic Quasicrystal

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Physical Review Letters 2024年第26期132卷 263801-263801页

作者： Zhaoyang Zhang Shun Liang Ismaël Septembre Jiawei Yu Yongping Huang Maochang Liu Yanpeng Zhang Min Xiao Guillaume Malpuech Dmitry Solnyshkov Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP F-63000 Clermont-Ferrand France International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Department of Physics National Laboratory of Solid State Microstructures and School of Physics 75231 Paris France

Theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localization due to the fractal spectrum and to the transition to diffusive bands via exceptional points, respectively. Here, we present an experimental study of a dodecagonal photonic quasicrystal based on electromagnetically induced transparency in a Rb vapor cell. First, we observe the suppression of the wave packet expansion in the Hermitian case. We then discover a new regime, where increasing the non-Hermiticity leads to delocalization, demonstrating that the behavior in non-Hermitian quasicrystals is richer than previously thought.

关键词： Electromagnetically induced transparency Localization Photonics Non-Hermitian systems Quasicrystals

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Thermodynamic optimization of closed air Brayton cycle and air-ORC combined cycle

Thermodynamic optimization of closed air Brayton cycle and a...

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International Conference on power engineering 2021, ICOPE 2021

作者： Qian, Yiran Zhang, Zhuohua Yi, Jingwei Chen, Weixiong Liu, Ming Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Nuclear Power Institute of China Chengdu610213 China

In order to improve the flexibility and adaptability of small mobile nuclear power systems, air is considered as an optional working fluid of nuclear Brayton cycle system. It can avoid the shortage of working fluid under extreme conditions, and ensure the system operation with tight working fluid supply. In this study, simple regenerative cycle (SRC), intercooling regenerative cycle (IRC) and corresponding air-ORC combined cycle (SRCC and IRCC) are proposed and modeled. Thermodynamic analysis of key parameters is conducted. Genetic algorithm (GA) is applied for multi-parameter optimization to achieve the maximum cycle efficiency. With the increase of pressure ratio (PR), the efficiency of SRC increases firstly and then decreases. Pressure ratio corresponding to the maximum cycle efficiency increases gradually with turbine inlet temperature. The efficiency of IRC is slightly lower than that of SRC in low pressure ratio region, but IRC maintains a higher efficiency in high pressure ratio region. For SRCC, isobutane has the best performance among three selected organic working fluids. The multi-parameter optimization result indicates that the IRCC has lower cycle efficiency comparing with SRCC, and SRCC shows the optimal performance among the four configurations. © 2021 The Japan Society of Mechanical Engineers.

关键词： Efficiency

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Study on the Dynamic Characteristics, Control Strategy and Load Variation Rate of the Concentrated Solar power Plant

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SSRN 2023年

作者： Li, Gen Du, Guanghan Liu, Guixiu School of Electric Power Engineering South China University of Technology Guangzhou510641 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

With more and more wind power and photovoltaic power connected to the electric power system, it has brought great challenges to the stability of the power grid. Concentrated solar power (CSP) plant as one form of solar power generation can undertake the task of load regulation and frequency regulation in power grid to balance the electricity demand and generation. However, the maximum load variation rate of the CSP plant is not known, which limits sufficient utilization of its advantages. In this study, a dynamic simulation model of the CSP plant was built using the APROS, and the dynamic characteristics were investigated by applying the step disturbances to molten salt flowrate, molten salt temperature, and the opening of steam regulating valve. Based on the results of dynamic characteristics, the control strategies were developed with the consideration of thermal storage in system and the feedforward signal of set load and load variation rate. Then, the maximum load increase and reduction rates within different load ranges were studied. The results indicated that the steam regulating valve could be used to control turbine power, molten salt flowrate could be used to control steam pressure, and the molten salt temperature could be used to control steam temperature. The designed control system could effectively follow the load variation, with the load deviation less than 0.3 MW and the steam temperature deviation less than 1.2 ℃ in the condition of load variation rate at 3% Pe·min-1. The maximum load increase and reduction rates were 11.57% Pe·min-1 and 8.94% Pe·min-1 within the load range of 75%THA-100%THA, and they were 10.42% Pe·min-1 and 7.46% Pe·min-1 within the load range of 50%THA-75%THA, respectively. © 2023, The Authors. All rights reserved.

关键词： Concentrated solar power

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Research on load characteristics of floating VAWT considering coupling of aerodynamics and hydrodynamics 32nd

Research on load characteristics of floating VAWT considerin...

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32nd International Ocean and Polar engineering Conference, ISOPE 2022

作者： Liu, Weiqin Luo, Wenping Li, Ye Zhang, Ding Departments of Ocean Engineering School of Naval Architecture Ocean and Energy Power Engineering Wuhan University of Technology Hubei Wuhan China Laboratory of Multiple Function Towing Tank State Key Laboratory of Ocean Engineering Shanghai Jiaotong University Shanghai China Marine design and research Institute of China Shanghai China

ISBN: (纸本)9781880653814

Vertical Axial Wind Turbine (VAWT) has advantages to utilize wind energy at vertical wind section and to adapt changeful wind direction so that VAWT becomes latest wind turbine type for deep-open sea. In order to discuss load characteristics of floating VAWT caused by coupling movement of blade and platform, a deep-sea floating H-type VAWT is regarded as the research object. A large platform based on computational fluid dynamic (CFD) was used to calculate the load of VAWT in the gas-liquid two-phase flow field, sliding and overset mesh were used to simulate the motion of the rotating blades and platform, the VOF method was used to accurately capture the position of the free liquid surface, and the load characteristics of the VAWT were obtained by combining the multi-grid refining technology. This method was validated by experiment data and used to simulate the load and motion of VAWT under a series of working conditions, and the aerodynamic and hydrodynamic performance of the floating VAWT and its variation with wave height and wave length are found by analyzing the simulation results. © 2022 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Hydrodynamics

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Thermodynamic Performance of Cacl2 Absorption Heat Pump Thermal Energy Storage System with Triple Storage Tanks

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SSRN 2023年

作者： Chen, Jinsen Zhou, Yuan Liu, Jiping Zhao, Yongliang Zhang, Shunqi Yan, Junjie MOE Key Laboratory of Thermal Fluid Science Engineering Xi'an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Absorption thermal energy storage has the characteristics of high thermal energy storage density (ESD) and low heat loss for long-term storage. To solve the coal-fired combined heat and power plant heat-power-coupling problem, in this work, an absorption heat pump thermal energy storage system (AHPTES) using CaCl2-water solution as the working fluid is proposed. A steady-state thermodynamic model of the system was constructed using Aspen Plus. Under the design conditions, the AHPTES system requires a tank volume of 464.61 m3 for one hour of operation, an ESD of 29.81 kW·h/m3, a thermal energy storage ratio of 46.50%, and a heating ratio of 53.54%. Compared to the dual-tank thermal energy storage system with H2O and CaCl2-water solutions as working fluids, the AHPTES system has 1.43 and 1.25 times higher ESD and 0.7 and 0.8 times lower tank volume, respectively. Then, the effects of CaCl2 mass fraction, driving pressure, evaporator outlet temperature, preheating temperature, and condensing temperature on the system performance are simulated. Improving the CaCl2 mass fraction, lowering the evaporator outlet temperature, and raising the condensing temperature and preheating temperature can boost the system's performance. At the optimal system performance, the required tank volume for one hour of system operation is 439.56m3, ESD can reach up to 37.39 kW·h/m3, heating ratio to 44.83%, and the energy storage ratio to 55.17%. Besides, raising the mass fraction of CaCl2 to 52% and decreasing the evaporator outlet temperature to 30 °C at 50% mass fraction resulted in crystallization of the system. © 2023, The Authors. All rights reserved.

关键词： Thermal energy

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Influence of Bentonite on Copper Corrosion in Simulated Repository Electrolyte

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SSRN 2024年

作者： Ning, Zhiyuan Zhou, Qulan Li, Na Macdonald, Digby D. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States

The impact of bentonite on the corrosion of oxygen-free copper (OF-Cu) and oxygen-free phosphorous copper (OFP-Cu) in prototypical groundwater environments (standard reference electrolyte, SRE) simulating the storage of copper High-Level Nuclear Waste (HLNW) cannisters in granitic rock repositories is explored. At low corrosion potentials (-0.1VSCE), bentonite suppresses copper corrosion in SRE through the anion-exclusion effect, with its inhibitory impact intensifying at higher bentonite concentrations. As the corrosion potential rises, bentonite’s enhanced adsorption of metal cations increases the corrosion current. Additionally, bentonite hydrolysis producing silicate ions that accelerates pitting corrosion, culminating in passive film breakdown. This dual mechanism may amplify intergranular corrosion. In environments where bentonite exacerbates corrosion, OFP-Cu demonstrates superior corrosion resistance, though the introduction of phosphorus may influence the acceleration of intergranular corrosion following passivity breakdown. © 2024, The Authors. All rights reserved.

关键词： Bentonite

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