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A volume of fluid simulation of the steady deformation and the drag of a single droplet in a flowing gas

Journal of Hydrodynamics 2021年第2期33卷 334-346页

作者： Zhi-bin Wang Zhong-wei Yang Lie-jin Guo Ren-jie Zhao State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChendu 610500China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

A method is proposed to investigate the steady deformation and the drag of a single droplet in a flowing gas at a high Reynolds *** volume of fluid(VOF)method is used to model the droplet surface *** direct numerical simulation(DNS)method is used to model the gas flow *** order to avoid the effect of the droplet acceleration on the drag and reduce the computation cost,a body force is added to the droplet to make it fixed at a constant *** body force is determined by using the Newton iteration *** simulated droplet aspect ratio and the drag coefficient agree well with the published experimental ***,the sources of the drag are analyzed and the effect of the Reynolds number and the Weber numbers on the droplet deformation and the drag are *** drag mainly comes from the pressure difference between the droplet-leading zone and the trailing zone,and the turbulence wake would increase the drag.

关键词： Droplet deformation steady drag volume of fluid(VOF) turbulent flow drag force

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Cobalt oxide and carbon modified hematite nanorod arrays for improved photoelectrochemical water splitting

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Chinese Chemical Letters 2017年第12期28卷 2207-2211页

作者： Miao Wang Meng Wang Yanming Fu Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an fiaotong UniversityXi'on 710049China

Given the proper band gap, low cost and good stability, hematite （α-Fe2O3） has been considered as a promising candidate for photoelectrochemical （PEC） water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide （COOx） and carbon （C） for the improved PEC performance, with a photocurrent density at 1.6V （vs. reversible hydrogen electrode, RHE） increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.

关键词： Hematite nanorodsSurface modificationPhotoelectrochemical water splittingWater oxidationElectrochemical impedance spectroscopy

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An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical sliding-pressure operation once-through boiler

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 300-304页

作者： TANG Renhu YIN Fei WANG Haijun CHEN Tingkuan The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Within the pressure range of 9-28 MPa,mass 200-500 kW/m2,experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees,a maximum outer diameter of 38.1 mm,and a thickness of 7.5 *** on the experiments,it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical ***,the heat transfer enhancement decreased near the critical *** supercritical pressure,the temperature difference between the wall and the fluid increased near the pseudo-critical temperature,but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical *** pressure is closer to the critical pressure,the temperature difference between the wall and the fluid increased greatly near the pseudo-critical *** transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat *** the rotational flow of the internal groove reduced the effect of natural convection,the internal wall temperature of internally ribbed tube uniformly distributed along the *** maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/*** the effect of acute variety of the fluid property on heat transfer,the correlation of heat transfer coefficient on the top of the internally ribbed tube was orovided.

关键词： thermal power engineering heat transfer supercritical pressure boiler internally ribbed tube departure from nucleate boiling

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Simulation of horizontal slug-flow pneumatic conveying with kinetic theory

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中国高等学校学术文摘·能源与动力工程 2007年第3期1卷 336-340页

作者： GU Zhengmeng GUO Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Wavelike slug-flow is a representative flow type in horizontal pneumatic *** theory was introduced to establish a 3D kinetic numerical model for wavelike slug gas-solid flow in this *** motion of particulate slugs in horizontal pipes was numerically *** formation and motion process of slugs and settled layer were *** characteristics of the flow,such as pressure drop,air velocity distribution,slug length and settled layer thickness,and the detailed changing characteristics of slug length and settled layer thickness with air velocity were *** results indicate that kinetic theory can represent the physical characteristics of the non-suspension dense phase flow of wavelike slug pneumatic *** experiment in this paper introduced a new idea for the numerical calculation of slug-flow pneumatic conveying.

关键词： slug-flow pneumatic conveying kinetic theory simulation

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Best estimate plus uncertainty analysis of the China advanced large-scale PWR during LBLOCA scenarios

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International Journal of Advanced Nuclear Reactor Design and Technology 2020年 2卷 34-42页

作者： Chang, Yuhao Wang, Mingjun Zhang, Jing Tian, Wenxi Qiu, Suizheng Su, G.H. Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

China advanced large-scale Pressurized Water Reactor (PWR) implements series of passive safety systems to provide core cooling and decay heat removal in case of some unexpected accidents. The development of reactor best estimate system analysis codes has realized the transition from conservative safety analysis to Best Estimate plus Uncertainty (BEPU) analysis for the purpose of achieving more realistic results and digging larger safety margins. The BEPU analysis during Large Break Loss of Coolant Accident (LBLOCA) has been widely used for the licensing application of Nuclear power Plants (NPPs). In this paper, the BEPU analysis of China advanced large-scale PWR was performed under the conditions of LBLOCA scenarios employing RELAP5 code. The models of reactor coolant system with all the passive safety systems were established and the influence of uncertainties of important parameters on the Peak Cladding Temperature (PCT) was evaluated. The results show the obtained PTC (1314 K) through the BEPU analysis is far below the 10CFR50.46 PCT acceptance criteria (1477 K) in case of LBLOCA and is also lower than the conservative calculation value (1348 K), indicating a larger safety margin. This work provides a meaningful evaluation method for China advanced large-scale PWR safety assessment. © 2020 Xi'an Jiaotong University

关键词： Pressurized water reactors

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Novel flow behaviors induced by a solid particle in nanochannels: Poiseuille and Couette

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Chinese Science Bulletin 2014年第20期59卷 2478-2485页

作者： Cheng-Zhen Sun Wen-Qiang Lu Bo-Feng Bai Jie Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University College of Physical Sciences University of Chinese Academy of Sciences

We conducted a molecular dynamics(MD)simulation to address the novel flow behaviors induced by a solid particle in *** basic flows,i.e.,Poiseuille and Couette,are involved in this *** Poiseuille flow,the distribution of number density exhibits fluctuations in the center of channel and near the walls,which are caused by the strong interactions from the atoms of particle and *** stronger external driving forces,the fluid atoms move toward the center of channel and some cavities appear in the fluidic *** external driving forces and bigger particles make the fluid moving quickly in *** Couette flow,the particle rotates under the velocity difference among particle atoms in the shear *** fluid atoms near the walls become infrequent and move to the center of *** velocities of the centrally-located fluid atoms decrease owing to the particle,resulting in an untypical non-linear Couette *** summary,the solid particle brings new fluid–solid interface and interactions,which induce several novel behaviors in nanochannel flows.

关键词：流动行为纳米通道固体粒子 Poiseuille流诱发 Couette流强相互作用固体颗粒

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Hydrogen production by catalytic gasification of cellulose in supercritical water

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Frontiers of Chemical Science and engineering 2008年第2期2卷 176-180页

作者： Yu GUAN Aixia PEI Liejin GUO State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K_(2)CO_(3) and Ca(OH)2 were selected as the catalysts(or promoters).The temperature was kept between 450uC and 500uC while pressure was maintained at 24–26 *** reaction time was 20 *** results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each *** 0.2 g K_(2)CO_(3) was added,the hydrogen yield could reach 9.456 mol?kg21 which was two times of the H2 amount produced without *** 1.6 g Ca(OH)2 was added,the H2 yield was 8.265 mol?kg21 which is lower than that obtained using K_(2)CO_(3) as catalyst but is still 1.7 times that achieved without *** with the results obtained using K_(2)CO_(3) or Ca(OH)2 alone,the use of a combination of K_(2)CO_(3) and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25%and 45%more than that obtained using K_(2)CO_(3) and Ca(OH)2 alone,*** was found that methane was the dominant product at relatively low *** the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.

关键词： biomass hydrogen production supercritical water gasification hydrogen

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Proposal and thermodynamic analysis of a steam methane reforming system integrated with thermochemical energy storage and a SCO₂ brayton cycle

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Journal of Energy Storage 2025年 127卷

作者： Fu, Yu Liu, Ming Wang, Zhu Xie, Tao Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Institute of Industrial Catalysis School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an 710049 China

Solar energy is a promising alternative to fossil fuels for providing heat in steam methane reforming (SMR) hydrogen production. However, the variability of solar energy requires effective storage solutions. This study presents a new SMR hydrogen production system that integrates thermochemical energy storage (TCES) utilizing a CaO/CaCO₃ cycle with a SCO₂ Brayton cycle. The system converts fluctuating solar energy into the stable chemical energy of CaO by calcinating CaCO₃ in the solar calciner, with the SMR reaction mainly heated by the exothermic reaction of CaO and CO₂. The SCO₂ Brayton cycle efficiently recovers heat from the high-temperature SMR products. Comprehensive thermodynamic analysis and evaluation models are developed. Results show that the proposed system performs well, achieving energy and exergy efficiencies of 73.49 % and 78.46 %, respectively, under benchmark conditions. The energy storage efficiency of TCES is 81.55 %, and the solar-to-chemical energy efficiency is 48.21 %. Integrating TCES significantly enhances the system's steady operation under fluctuating solar energy conditions. The calciner accounts for the largest share of exergy destruction at 31.63 %, followed by the carbonator at 17.50 %. Sensitive analyses of key operating parameters indicate that higher CaO conversion rate and storage temperature enhance energy storage, energy, and exergy efficiencies. Besides, the energy and exergy efficiencies decrease with the increasing SMR reaction pressure but increase with rising reaction temperature. When the S/C is 2.0, these efficiencies reach their maximum values of 75.42 % and 78.63 %, respectively. © 2025 Elsevier Ltd

关键词： Hydrogen production SCO2 Brayton cycle Solar energy Steam methane reforming Thermochemical energy storage

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Evaluation of frictional pressure drop correlations for air-water and air-oil two-phase flow in pipeline-riser system

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Petroleum Science 2024年第2期21卷 1305-1319页

作者： Nai-Liang Li Bin Chen School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049ShaanxiChina

Accurate prediction of the frictional pressure drop is important for the design and operation of subsea oil and gas transporting system considering the length of the pipeline. The applicability of the correlations to pipeline-riser flow needs evaluation since the flow condition in pipeline-riser is quite different from the original data where they were derived from. In the present study, a comprehensive evaluation of 24prevailing correlation in predicting frictional pressure drop is carried out based on experimentally measured data of air-water and air-oil two-phase flows in pipeline-riser. Experiments are performed in a system having different configuration of pipeline-riser with the inclination of the downcomer varied from-2°to-5°to investigated the effect of the elbow on the frictional pressure drop in the riser. The inlet gas velocity ranges from 0.03 to 6.2 m/s, and liquid velocity varies from 0.02 to 1.3 m/s. A total of885 experimental data points including 782 on air-water flows and 103 on air-oil flows are obtained and used to access the prediction ability of the correlations. Comparison of the predicted results with the measured data indicate that a majority of the investigated correlations under-predict the pressure drop on severe slugging. The result of this study highlights the requirement of new method considering the effect of pipe layout on the frictional pressure drop.

关键词： Frictional pressure drop Pipeline-riser Gas-liquid two-phase flow Severe slugging Correlation

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Performance of vertical axis water turbine with eye-shaped baffle for pico hydropower

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Frontiers in Energy 2022年第4期16卷 683-696页

作者： Zhuohuan HU Dongcheng WANG Wei LU Jian CHEN Yuwen ZHANG Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 20093China Department of Mechanical and Aerospace Engineering University of MissouriColumbiaMO 65211USA

t A series of inline pico hydropower systems,which could be used in confined space,especially for water distribution networks(WDNs),was designed and *** turbine with an eye-shaped vertical water baffle was developed to evaluate the hydraulic performance.A three-dimensional dynamic mesh was employed and the inlet velocity was considered as the inlet boundary condition,whereas the outlet boundary was set as the ***,numerical simulations were conducted and the standard k-εturbulence model was found to be the best capable of predicting flow features through the comparison with the experimental *** effects of the opening diameter of the water baffle and installation angle of the rotor on the flow field in the turbine were *** results suggested that the water baffle opening at d=30 mm and the rotor at a 52°angle could achieve the highest efficiency of 5.93%.The proper eye-shaped baffle not only accelerates the fluid flow and generates positive hydrodynamic torque,but also eliminates the flow *** scheme proposed in this paper can be exploited for practical applications in the water pipelines at various conditions and power requirements.

关键词： vertical axis water turbine eye-shaped vertical water baffle pico hydropower

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