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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

Room-temperature photodeposition of conformal transition metal based cocatalysts on BiVO4 for enhanced photoelectrochemical water splitting

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Nano Research 2020年第1期13卷 231-237页

作者： Lu Wang Tao Zhang Jinzhan Su Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy&Power EngineeringXi’an Jiaotong UniversityXi’an710049China

Photoelectrochemical(PEC)water splitting using semiconductors offers a promising way to convert renewable solar energy to clean hydrogen ***,due to the sluggish reaction kinetics of water oxidation,significant charge recombination occurred at the photoanode/electrolyte interface and cause decrease of its PEC *** reduce the surface recombination,we deposit different transition metal complexes on BiVO4 nanocone arrays by a versatile light driven in-situ two electrode photodeposition approach without applied *** cobalt phosphate“Co-Pi”,nickel borate“Ni-Bi”and manganese phosphate“Mn-Pi”complexes were deposited on BiVO4 nanocone arrays to form core-shell structure photoanode,all of which lead to enhanced photoelectrochemical *** photocurrent of the Co-Pi/BiVO4 photoanode under front-side illumination for 5 min is increased by 4 folds comparing to that of bare BiVO4 photoanode at 0.6 V ***,reaching a hole transfer efficiency as high as 94.5%at 1.23 V *** proposed photodeposition strategy is simple and efficient,and can be extended to deposite cocatalyst on other semiconductors with a valence band edge located at a potential more positive than the oxidation potential of transition metal ion in the cocatalyst.

关键词： bismuth vanadate photoelectrochemcial water splitting conformal photodeposition cocatalyst

Analysis of Gas-Cooled Micro Modular Reactor (MMR) Fuel

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SSRN 2024年

作者： Deng, Chaoqun Zhu, Siyang He, Yanan Wu, Yingwei He, Kai Zhang, Jing Su, Guanghui 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 China Nuclear Power Engineering Co. Ltd. Beijing100840 China

The gas-cooled micro modular reactor (MMR) is a novel concept with compact fuel form consists of thousands of tri-isotropic fuel (TRISO) particles dispersed in silicon carbide matrix. The MMR fuel is high volume packing fraction and horizontally placed within graphite channels. Due to the complexity of the fuel structure and the challenges involved in simulation, a multi-scale and multi-physics coupled analyses method of MMR fuel was realized in this work by implementing physical models into the open-source finite element platform MOOSE. Though the simulation of the typical design MMR fuel during normal operation, the thermal-mechanical analysis and the failure analysis were conducted. The results show that the arrangement of MMR fuel horizontally within graphite channels resulted in non-uniform gap between the fuel and graphite brick, leading to an "off-center" temperature distribution within the fuel, the peak temperature is about 1314 K. Higher-temperature sub-zones exhibit greater internal pressure within TRISO and show greater tensile stress in the Chemical Vapor Deposited Silicon Carbide (CVD-SiC) layer. Regarding fuel failure analysis, this work found limited impact from Pd penetration and kernel migration. Pressure-induced particle failure, closely linked with stress in CVD-SiC, emerges as the primary failure criterion. The overall probability of fuel failure remains relatively low, with a maximum probability of 4.1×10-5. Statistical data reveals that a significant majority (71%) of TRISO particles exhibit a failure probability below 2×10-5, while only 8.8% reach 4×10-5 © 2024, The Authors. All rights reserved.

关键词： Graphite

Study on the Aerodynamic Characteristics of Vertical Axis Wind Turbines Based on Omnidirectional Guide Grids

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SSRN 2023年

作者： Zhou, Ye Xiandong, Li Hao, Yu Renhao, Ruan School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

In order to analyze the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine, a combination of the inclination angle, relative distance, and thickness of the blade grid was designed to compare the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine under various tip speed ratio conditions. The results show that the wind power utilization rate and moment coefficient of the wind turbine under the effect of the omnidirectional deflector grille tend to increase and then decrease as the inclination angle increases, and the best effect on the wind turbine aerodynamic performance is achieved when the inclination angle is 0°, the wind turbine moment is greatly increased, and the range of effective operating conditions is expanded. When the inclination angle is 0° at all relative distances, the omnidirectional deflector grid can improve the pressure distribution of wind turbine blades, and the corresponding pneumatic performance improvement increases with the relative distance. When the relative distance is 2.6, the best effect on the wind turbine's aerodynamic performance is achieved. By changing the number of deflector blades and chord length to adjust the grid consistency, the vertical axis wind turbine aerodynamic performance curve under the action of the omnidirectional deflector shifts toward the direction of the large tip speed ratio as the grid consistency increases, and the corresponding wind energy utilization rate and torque coefficient peak are increasing and then decreasing when the chord length is 374mm (grid consistency is 0.267). When the chord length is 374mm (the blade thickness is 0.267), the best effect on the aerodynamic performance of the vertical axis wind turbine is achieved. © 2023, The Authors. All rights reserved.

关键词： Vertical axis wind turbine

Estimation of particle depth from two defocused images using the Fourier transform

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Particuology 2020年第2期18卷 48-54页

作者： Wu Zhou Xu Luo Benting Chen Yukun Zhang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Depth from defocus is one technology for depth *** estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging *** images are processed with the Fourier transform to obtain the characteristic parameter(i.e.,the standard deviation of the relative blur kernel of these two defocused images).First,we theoretically analyze the functional relationship between the object depth and the standard deviation or variation of the relative blur ***,we verify the relationship *** analyze the influence of particle size,window size and image noise on the calibration curves using both numerical simulations and *** obtain the depth range and accuracy of this measurement system *** the verification experiments,we use a sample of glass microbeads and the irregularly-shaped dust particles on a microscope *** of these experiments present a suitable depth measurement ***,we apply the measuring system to the depth estimation of drops from a small anti-fogging *** results show that our system and image processing algorithm are robust for different types of particles,facilitating the in-line three-dimensional positioning of particles.

关键词： Depth from two defocused images Fourier transform Standard deviation of relative blur kernel Drops depth measurement Sensitivity and accuracy analysis

Numerical Study of Multi-Factor Coupling Effects on Energy Conversion Performance of Nanofluidic Reverse Electrodialysis

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Frontiers in Heat and Mass Transfer 2025年第2期23卷 507-528页

作者： Hao Li Cunlu Zhao Jinhui Zhou Jun Zhang Hui Wang Yanmei Jiao Yugang Zhao School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing211816China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xi’an Jiaotong UniversityXi’an710049China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing210016China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai200093China Key Laboratory of Icing and Anti/De-icing China Aerodynamics Research and Development CenterMianyang621000China

Based on the rapid advancements in nanomaterials and nanotechnology,the Nanofluidic Reverse Electrodialysis(NRED)has attracted significant attention as an innovative and promising energy conversion strategy for extracting sustainable and clean energy fromthe salinity gradient ***,the scarcity of research investigating the intricate multi-factor coupling effects on the energy conversion performance,especially the trade-offs between ion selectivity and mass transfer in nanochannels,of NRED poses a great challenge to achieving breakthroughs in energy conversion *** numerical study innovatively investigates the multi-factor coupling effect of three critical operational factors,including the nanochannel configuration,the temperature field,and the concentration difference,on the energy conversion processes of *** this work,a dimensionless amplitude parameter s is introduced to emulate the randomly varied wall configuration of nanochannels that inherently occur in practical applications,thereby enhancing the realism and applicability of our *** results reveal that the application of a temperature gradient,which is oriented in opposition to the concentration gradient,enhances the ion transportation and selectivity simultaneously,leading to an enhancement in both output power and energy conversion ***,the increased fluctuation of the nanochannel wall from s=0 to s=0.08 improves ion selectivity yet raises ion transport resistance,resulting in an enhancement in output power and energy conversion efficiency but a slight reduction in ***,with increasing the concentration ratio cH/cL from 10 to 1000,either within a fixed temperature field or at a constant dimensionless amplitude,the maximumpower consistently attains its optimal value at a concentration ratio of 100 but the cation transfer number experiences amonotonic decrease across this entire range of concentration ***,uponmodifying the ope

关键词： Salinity gradient energy nanofluidic reverse electrodialysis energy conversion nanochannel configuration multi-factor coupling effect

Anchoring Single Nickel Atoms on Carbon-vacant Carbon Nitride Nanosheets for Efficient Photocatalytic Hydrogen Evolution

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Chemical Research in Chinese Universities 2022年第5期38卷 1243-1250页

作者： LIN Zhi ZHANG Zhengqi WANG Yiqing PENG Zhiming WANG Xinxin WANG Ruizhe HUANG Yu-Cheng MENG Fanqi LI Mingtao DONG Chung-Li ZHANG Qinghua GU Lin SHEN Shaohua International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049P.R.China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanP.R.China Institute of Physics Chinese Academy of SciencesBeijing 100190P.R.China

Polymeric carbon nitride(PCN)has emerged as a promising candidate for photocatalytic hydrogen evolution,but its dependence on scarce and high-cost noble metal co-catalysts severely limits its extensive *** will be of great promise to develop non-noble metal single-atom co-catalysts with low-cost and high atom utilization to improve the photocatalytic performance over ***,single Ni atoms are successfully anchored onto carbon-vacant PCN nanosheets(CCN-SANi)via a two-step ammonia thermal treatment and photo-deposition *** calculations and experimental results demonstrate that the optical absorption property and the charge transfer ability of CCN-SANi have been significantly improved with the introduction of single Ni atoms to form Ni-N3 *** comparison to carbon-vacant PCN(CCN)loaded with Ni clusters,the obtained CCN-SANi exhibits 11.4 times increased photocatalytic performance,with the highest hydrogen evolution rate reaching 511μmol/(g·h),which is even 1.7 times higher than that of CCN loaded with Pt *** research proposes an inspiring and reliable strategy to design novel single-atom semiconducting polymers with electronic structures manipulated for efficient photocatalysis.

关键词： Photocatalytic hydgogen evolution Single metal atom Polymeric carbon nitride

Supercritical Co2 -Promoted Degradation of Polystyrene to Aromatic Oils with Nio@C Catalyst

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SSRN 2024年

作者： Liu, Yanbing Shi, Jinwen Zhuang, Zitong Kang, Xing Mao, Liuhao Li, Yi Jin, Hui Zhao, Qiuyang Guo, Liejin International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 28 West Xianning Road Shaanxi Xi’an710049 China

Exploring new system for chemical recycling of plastic is an effective way to convert plastic waste into energy. Herein, the use of supercritical CO2 (Sc-CO2) to promote the catalytic degradation of polystyrene (PS) with high yield of aromatic oils was proposed. Sc-CO2 provided a homogeneous environment for the reaction, which not only facilitated the swelling of PS, but also inhibited the formation of coke, beneficial for the degradation of PS to aromatic oils. Importantly, CO2 was be consumed as an oxidant to generate new product and reduce greenhouse gas emission. The doped carbon material in NiO, which was stable in Sc-CO2 and had a simple preparation process, enriched the porous structure and increased the acidic sites, thus improving the catalytic activity. Under the co-action of Sc-CO2 and NiO@C, the yield of aromatic oils produced from PS was up to 89.3 ± 0.6 wt% at 300oC with a reaction time of 2 h and a catalyst loading amount of 10 wt%. Moreover, the NiO@C catalyst were used for three cycles without obvious change in the catalytic performance. The efficient catalytic degradation of PS to aromatic oils by Sc-CO2 promoted NiO@C catalysis provides a potential route for simultaneously recycling plastic and sequestering carbon. © 2024, The Authors. All rights reserved.

关键词： Carbon dioxide

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

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

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