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Wall-to-bed heat transfer in supercritical water fluidized bed using CFD-DEM

Particuology 2021年第3期19卷 113-123页

作者： Tianning Zhang Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi’an Jiaotong UniversityXi’anShaanxi 710049PR China

Supercritical water fluidized bed(SCWFB)reactors are designed to gasify biomass or coal with high *** this paper,the wall-to-bed heat transfer characteristics in SCWFB are studied using the computational fluid dynamics and discrete element method(CFD-DEM)coupled with a constant heat flux *** different methods are considered to deal with the multiphase heat flux boundary in CFD-DEM because there is currently no single widely accepted ***’s method predicts a more accurate wall-to-bed heat transfer coefficient in SCWFB than Lattanzi’s method according to comparisons of the simulation results with an empirical *** influences of temperature,pressure,velocity,and the solid phase properties,such as the particle diameter,particle heat capacity,particle thermal conductivity,and particle density,on the SCWFB wall-to-bed heat transfer characteristics are studied based on Zhang’s *** simulation results help reveal the SCWFB heat transfer characteristics.

关键词： Supercritical water Fluidized bed Heat transfer DEM-CFD Constant heat flux

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Operational efficiency improvement in a water supply network: Machine learning-enhanced leakage identification and water resource conservation

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Journal of Water Process engineering 2025年 75卷

作者： Liu, Hongbo Zhang, Junbo An, Wenhui Chen, Yang Yuan, Xiang Zhang, Guosheng Lichtfouse, Eric Ma, Jiale Huang, Jin Tu, Yiqian School of Environment and Architecture University of Shanghai for Science and Technology 516 Jungong Road Shanghai 200093 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China Shanghai Urban Construction Design and Research Institute (Group) Co. Ltd. Shanghai 200125 China

Pipeline ruptures in water supply networks can induce significant water loss and may pose risks of water quality deterioration, including potential contamination by pathogens and pollutants. This issue can be addressed by predicting the location of leakage points in the pipeline network and controlling the leakage. Here we designed a hydraulic model for leakage localization using a genetic algorithm-backpropagation neural network, to predict the leakage points in the water supply system of an exposition area consuming 117,211 m³ of water per day in Eastern China. Then, using the model results, pressure-regulating valves were installed in areas with lower network safety. Results show that the error in predicting the leakage points localization ranged from 14.48 m to 121.69 m. The installation of pressure-regulating valves, reduced the average water pressure from 33.54 m to 32.64 m (2.7 %) and, in turn, decreased the simulated background leakage by 9684 m³ of water per day. Compared to traditional acoustic-based methods, the proposed machine learning approach enables more accurate leak localization by leveraging pressure variation features. © 2025 Elsevier Ltd

关键词： Pipeline leakage Point leakage model Pressure monitoring Pressure regulating valve Supply water

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Rapid modeling of transient processes in hydrogen-blended natural gas pipelines featuring injection and withdrawal points

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International Journal of Hydrogen Energy 2025年

作者： Gong, Junhua Zhou, Chaoqun Wang, Yanxin Deng, Yajun Chen, Yujie Wang, Peng Yu, Bo Chen, Bin Yu, Zhipeng Wang, Bohong School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China Changqing Oil and Gas Transportation Branch of Northwest Company of PipeChina Xingqing District Ningxia Yinchuan City750004 China PipeChina Engineering Technology Innovation Co.Ltd Tianjin300450 China School of Petroleum Engineering Yangtze University Wuhan430100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National & Local Joint Engineering Research Center of Harbor Oil & Gas Storage and Transportation Technology/Zhejiang Key Laboratory of Pollution Control for Port-Petrochemical Industry Zhejiang Ocean University Zhoushan316022 China

Blending hydrogen into natural gas pipelines enables the large-scale delivery and application of hydrogen, contributing to carbon emission reduction and promoting the transition to cleaner energy sources. Accurate and efficient predictions of transient processes in such pipelines are critical for effective management and operation. This study proposes a Fourier Neural Operator (FNO)-based model for the rapid prediction of transient processes in hydrogen-blended pipelines with injection and withdrawal points. The model is trained using numerical simulation data of pressure and flow dynamics, with initial conditions, boundary conditions, and the hydrogen blending ratio as inputs to predict hydraulic parameters along the pipeline over time. By optimizing data preprocessing and neural network hyperparameters, the model achieves high accuracy and efficiency in predicting hydraulic states. The FNO model achieves average Root Mean Squared Errors (RMSEs) of 1.06 × 10−3, 1.64 × 10−3, and 7.40 × 10−4 for pressure, flow rate, and density, respectively, with the Coefficient of Determination (R2) exceeding 0.99 for all three variables. Furthermore, the model demonstrates strong generalization capabilities, accurately predicting hydraulic states for pipeline topologies and scenarios beyond the training data. In these cases, the RMSE remains in the order of 10−3 or smaller. For a 100 km pipeline, the computational efficiency of the FNO model is at least 969 times higher than that of traditional numerical methods, with the maximum efficiency improvement reaching 5168 times as the number of pipeline cases simultaneously predicted increases. These results highlight the potential of the FNO model for real-time applications in hydrogen-blended natural gas pipeline management. © 2025 Hydrogen Energy Publications LLC

关键词： Mean square error

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Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

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Particuology 2023年第6期77卷 128-135页

作者： Chao Zhang Zhichao Zhang Longxiang Bu Yang Yang Wei Xiong Yueshe Wang School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai200093China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol ***,knowledge on the morphology of surfactant particles after the adsorption of water is *** this study,the interaction between water and particles composed of surface active malonic acid(MA)or adipic acid(AA)are simulated based on the molecular dynamics *** key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium *** show that demixed structure 1 with the adsorption of water clusters on acid grain,mixed structure and demixed structure 2 with acids coating on water droplet can be *** temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then *** the standard atmospheric temperature(280-330 K),the surface propensity of MA and AA increases with increasing water content and alkyl group,and its sensitivity to temperature and water content varies ***,all surfactants at the particle surface orient their hydrophobic groups toward the *** findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

关键词： Aerosol particles Surfactant Surface propensity Hygroscopic growth Molecular dynamics

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Extension of the pressure correction method to zero-Mach number compressible flows

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Science China(Technological Sciences) 2009年第6期52卷 1583-1595页

作者： HE YaLing HUANG Jing TAO YuBing TAO WenQuan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy&Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

In the present paper,the classical pressure correction method was extended into low Mach number compressible flow regime by integrating equation of state into SIMPLE *** self-developed code based on this algorithm was applied to predicting the lid-driven cavity flow and shock tube prob-lems,and the results showed good agreement with benchmark solutions and the Mach number can reach the magnitude of as low as *** attenuation of sound waves in viscous medium was then *** results agree well with the analytical solutions given by theoretical *** demonstrated that the present method could also be implemented in acoustics field simulation,which is crucial for thermoacoustic simulation.

关键词： thermoacoustic engine pressure correction method low Mach number compressible flow

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Ferrites boosting photocatalytic hydrogen evolution over graphitic carbon nitride: a case study of(Co, Ni)Fe_2O_4 modification

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Science Bulletin 2016年第4期61卷 292-301页

作者： Jie Chen Daming Zhao Zhidan Diao Miao Wang Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

The charge cartier separation and surface catalytic redox reactions are of primary importance as elementary steps in photocatalytic hydrogen evolution. In this study, both of these two processes in photocatalytic hydrogen evolution over graphitic carbon nitride （g-C3N4） were greatly promoted with the earth-abundant ferrites （Co, Ni）Fe2O4 modification. CoFe2O4 was further demonstrated to be a better modifier for g-C3N4 as compared to NiFe2O4, due to the more efficient charge carrier transfer as well as superior surface oxidative catalytic activity. When together loading CoFe2O4 and reductive hydrogen production electrocatalyst Pt onto g-C3N4, the obtained Pt/g-C3N4/CoFe2O4 photocatalyst achieved visible-light （2 〉 420 nm） hydrogen production rate 3.5 times as high as Pt/g-C3N4, with the apparent quantum yield reaching 3.35 % at 420 nm.

关键词： Graphitic carbon nitride FerritesPhotocatalytic water splitting Solar hydrogenconversion

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Experimental and kinetic study on ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures by shock tube

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Chinese Science Bulletin 2011年第26期56卷 2853-2861页

作者： ZHANG YingJia HUANG ZuoHua WEI LiangJie NIU ShaoDong State Key Laboratory of Multiphase Flow in Power Engineering Xi' an Jiaotong University Xi'an 710049 China

Ignition delay times of methane/hydrogen/oxygen/nitrogen mixtures with hydrogen amount-of-substance fractions ranging from 0–20% were measured in a shock tube *** ambient temperature varied from 1422 to 1877 K and the pressure was maintained at 0.4 MPa behind the reflected shock *** experiments were conducted at an equivalence ratio of *** fuel mixtures were diluted with nitrogen gas so that the nitrogen amount-of-substance fraction was 95%.The experimental ignition delay time of the CH4/H2 mixture decreased as the hydrogen amount-of-substance fraction *** enhancement of ignition by hydrogen addition was weak when the ambient temperature was >1750 K,and strong when the temperature was <1725 *** ignition delay time of 20% H2/80% CH4 was only one-third that of 100% CH4 at 1500 K.A modified model based on GRI-Mech 3.0 was proposed and used to calculate the ignition delay times of test *** calculated results agreed with the experimental ignition delay *** sensitivity analysis showed that HO·+H2 →H·+H2O was the main reaction for the formation of the H· at 1400 *** the hydrogen amount-of-substance fraction increased,chain branching was enhanced through the reaction H·+O2→O·+HO·,and this reduced the ignition delay *** 1800 K,the methyl radical (H3C·) became the key species that influenced the ignition of the CH4/H2/O2/N2 mixtures,and sensitivity coefficients of the chain termination reaction 2H3C·(+M)→C2H6(+M),and chain propagation reaction HO2+H3C·→HO·+CH3O decreased,which reduced the influence of hydrogen addition on the ignition of the CH4/H2 mixtures.

关键词：点火延迟时间混合物动力学激波管氢气实验氮气甲烷

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Supersonic shear layer characteristics of two fluids with a splitter plate

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 1-10页

作者： Bai, Yuping Hong, Yibo Zhao, Quanbin Chen, Weixiong Chong, Daotong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Supersonic shear layer development affects mixing between the primary and secondary fluids in a supersonic ejector substantially. The splitter plate plays a key role in shear layer development in the near-trailing-edge region. In this paper, supersonic shear layers with various splitter plate thicknesses are calculated and analyzed. Two types of instability modes are found when various splitter plate thicknesses are used. The shock wave strength and absolute unstable region determine the instability modes. Shock waves can limit instability development but an absolute unstable region promotes instability development. Velocity thickness growth rates are found to be the result of the merging process between two or more adjacent vortices in the transition region. The number of vortices that merge depends on the ratio of the vortex shedding and nature frequencies. The velocity thickness growth rates are larger under the local instability mode than under the global instability mode since three vortices merge under the former mode but two vortices merge under the latter. This study may provide a helpful reference for the design of supersonic ejectors. © 2021 Xi'an Jiaotong University

关键词： Vortex flow

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Measurement of laminar burning velocities and analysis of flame stabilities for hydrogen-air-diluent premixed mixtures

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Chinese Science Bulletin 2009年第5期54卷 846-857页

作者： HU ErJiang HUANG ZuoHua HE JiaJia JIN Chun MIAO HaiYan WANG XiBin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The laminar burning velocities and Markstein lengths of the hydrogen-air-diluent mixtures were meas-ured at different equivalence ratios (0.4―1.5), different diluents (N2, CO2 and 15%CO2+85%N2) and di-lution ratios (0, 0.05, 0.10 and 0.15) by using the outwardly expanding flame. The influences of flame stretch rate on the flame propagation characteristics were analyzed. The results show that both the laminar burning velocities and the Markstein lengths of the hydrogen-air-diluent mixtures decrease with the increase of dilution ratio. The decrease in Markstein lengths means that adding diluents into the hydrogen-air mixtures will decrease the diffusional-thermal instability of the flame front. For a specified dilution ratio, the laminar burning velocities give their maximum values at an equivalence ratio of 1.8. The Markstein lengths increase with the increase of the equivalence ratio monotonously regardless of the diluents. The study shows that CO2 as the diluent has a greater impact on the laminar flame speed and the flame front stability than N2 as the diluent.

关键词：氢气空气混合火焰特性燃烧速度稳定性

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Evaluating the chemical kinetics of aluminium/alumina/water reactions using molecular dynamics

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Computational Materials Science 2025年 257卷

作者： Zhao, Hao Zhang, Yingjia Liu, Yuncong Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Shaanxi Xi'an710049 China

Strength of aluminium in generating heat and hydrogen through water reaction highlight its potential as a green hydrogen carrier, but the formation of a passive oxide layer (alumina) inhibits further reactions thus hydrogen yield. This study employs reactive molecular dynamics (MD) simulations with the ReaxFF force field to investigate interactions between water and alumina-coated aluminium surfaces at temperatures ranging from 1000 K to 2500 K. Analysis of diffusion-driven reaction kinetics shows that hydrogen generation is primarily controlled by hydrogen atom diffusion within the aluminium bulk. Higher temperatures significantly accelerate both diffusion and reaction rates, shifting the mechanism from diffusion-limited to chemically controlled. Atomic-level reaction pathway analysis, using an in-house atom status tracing code, reveals the dynamic evolution of aluminium atom states. The results emphasize the roles of hydrogen and oxygen diffusion and indicate that O–H bond cleavage mainly proceeds through internal atomic diffusion. These findings offer detailed atomic-scale insight into the aluminium-water reaction, capturing both oxidizer diffusion and thermal effects. The study highlights the importance of thermal activation in enhancing reaction efficiency and safety, reinforcing aluminium's potential for green hydrogen production in carbon–neutral energy systems. © 2025 Elsevier B.V.

关键词： Rate constants

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