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Toward the influence of fluid convection on filtered drag force in fluidized gas-particle flows

Powder Technology 2025年 460卷

作者： Jiang, Ju Yuan, Shouzheng Chen, Xiao Yang, Bolun Zhou, Qiang School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Mesoscale drag modeling for gas-solid flows is typically based on fully-periodic systems where fluid convection is insignificant. This study examines a series of 2D sudden-expanded fluidized beds (SEFBs) to investigate the effects of fluid convection on the filtered drag force. A priori analysis indicates that the volumetric force induced by convection has a notable impact on the filtered drag force, and correlations of drag force using traditional markers (such as solid volume fraction, slip velocity, and filter size) fail to provide accurate predictions. In contrast, the gas-phase pressure gradient shows a good correlation with drag force when strong convection is present. Posterior tests in the SEFBs with several existing drag models reveal that the predictive capacity of drag models constructed with traditional markers declines under conditions with strong convection, whereas the drag model incorporating the gas-phase pressure gradient still performs well. © 2025 Elsevier B.V.

关键词： Drag coefficient

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Electrochemical evolution of a metal oxyhydroxide surface on two-dimensional layered metal phosphorus trisulfides enables the oxidation of amine to nitrile

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Carbon Energy 2025年第3期7卷 133-147页

作者： Binglan Wu Karim Harrath Marshet Getaye Sendeku Tofik Ahmed Shifa Yuxin Huang Jing Tai Fekadu Tsegaye Dajan Kassa Belay Ibrahim Xueying Zhan Zhenxing Wang Elisa Moretti Ying Yang Fengmei Wang Alberto Vomiero State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijingChina CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology(NCNST)BeijingChina Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of EducationCollege of Chemistry&Materials ScienceNorthwest UniversityXi'anChina State Key Laboratory of Multiphase Flow in Power Engineering International Research Center for Renewable EnergyXi'an Jiaotong UniversityShaanxiChina Fundamental Science Center of Rare Earths Ganjiang Innovation AcademyChinese Academy of ScienceGanzhouChina Ocean Hydrogen Energy R&D Center Research Institute of Tsinghua University in ShenzhenShenzhenChina Department of Molecular Sciences and Nanosystems Ca'Foscari University of VeniceVenezia MestreItaly Testing and Analysis Center Institute of Chemistry Chinese Academy of SciencesBeijingChina Department of Engineering Sciences and Mathematics Division of Materials ScienceLuleåUniversity of TechnologyLuleåSweden

Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of ***,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))***,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)*** calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.

关键词： 2D layered materials benzylamine oxidation metal phosphorus trichalcogenides surfacereconstructed heterostructure

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Prediction of acoustic agglomeration enhanced by solid seed particles using the DSMC method

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Advanced Powder Technology 2025年第6期36卷

作者： Su, Junxu Wu, Zhihao Fan, Fengxian Hu, Xiaohong Su, Mingxu 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 University of Shanghai for Science and Technology Shanghai200093 China

Acoustic agglomeration enhanced by large-sized solid seed particles is investigated using the direct simulation Monte Carlo (DSMC) method. The process of acoustic agglomeration is revealed in terms of temporal evolution of velocities, diameters, and number weights of simulated particles, as well as normalized concentration and average diameter of small particles. Furthermore, the enhancement of acoustic agglomeration by the solid seed particles is evaluated at varying parameters. The results show that the agglomeration performance is enhanced within a shorter residence time when the solid seed particles are present. Increasing acoustic intensity or solid seed particle concentration leads to more efficient acoustic agglomeration, while the acoustic frequency, particularly beyond 2 kHz, has little effect on agglomeration performance. Moreover, a noticeable increase in agglomeration efficiency is observed when the seed particle diameter increases from 20 to 40 µm. However, once it exceeds 40 µm, the increase in agglomeration efficiency diminishes. © 2025 The Society of Powder Technology Japan.

关键词： Agglomeration

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Molecular dynamics study on bubble nucleation characteristics on rectangular Nano-Grooved surfaces

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Journal of Molecular Liquids 2025年 420卷

作者： Li, Zhibin Lou, Jiacheng Wu, Xiaoyi Li, Xujun Chang, Fucheng Wang, Hengyuan Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China

The micro/nanoscale structures on metal surfaces are of significant research interest for boiling heat transfer and exhibit great application potential in the thermal management of high-power electronic devices. This study employs the molecular dynamics simulation method to investigate the boiling heat transfer characteristics of hydrophilic rectangular shallow nano-groove structures, comparing them with the smooth surface. The phase transition heat transfer characteristics of liquid films on the smooth surface, single rectangular groove (SRG) surface, and overlapping rectangular groove (ORG) surface are revealed by analyzing the variations of parameters such as energy contour diagrams, bubble volume, liquid film temperature, and average potential energy. The research results indicate that water molecules are in a solid-like state within shallow grooves, while the nucleation sites of initial bubbles form randomly outside the grooves. During the initial heating and bubble growth, the initial nucleation time and bubble growth rate of ORG are slower than those of SRG, due to the small rectangular groove on ORG that diminishes the energy transfer efficiency. During bubble formation and growth, the average kinetic energy within the liquid film fluctuates at the nucleation moment in the critical nucleation region, and the average potential energy rises from −0.083 eV. These findings provide a theoretical basis for the micro/nanoscale structure design of vapor-liquid phase transition thermal management devices. © 2024 Elsevier B.V.

关键词： Kinetic energy

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Molecular dynamics revealing the non-monotonic variation of oil–water interfacial tension under the effect of cations and asphaltenes

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Journal of Molecular Liquids 2025年 431卷

作者： Zhang, Faxue Wen, Boyao Lu, Xi Wang, Haibo Luo, Zhengyuan Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Petroleum Exploration and Production Research Institute of Sinopec Beijing China

The cations can significantly affect the interfacial dynamics of asphaltene molecules, which greatly change the mechanics of oil–water interfaces and thus have a remarkable impact on the chemical flooding process of heavy oil. However, Due to the weak amphiphilic property of asphaltene, the effects of cations on the interfacial behaviors of asphaltene as well as the interfacial mechanics are still unclear. Here, we study the effects of different types and concentrations of cations (Na+, Ca2+ and Mg2+) on the interfacial tension of oil–water systems with different asphaltenes (C5Pe) concentrations by using molecular dynamics simulations. As asphaltene concentration rises, the stronger interactions between cation and asphaltene induce an interfacial enrichment of asphaltenes, resulting in a decrease of interfacial tension. The cations have a more prominent impact on the interfacial tension when the oil–water interfaces reach supersaturated adsorption state of asphaltene molecules. The interfacial tension shows a non-monotonic variation with cation concentration increasing, which has a minimum at intermediate cation concentrations in our simulations. We explain this non-monotonic dependence of interfacial tension on cation concentration by a coupling effect of cations and asphaltene molecules. Under low cation concentrations, the interaction between cations and asphaltenes gradually enhances with cation concentration increasing, leading to a weaker π–π interaction between asphaltenes. Consequently, the asphaltene aggregates disperse and individual asphaltene molecules can easily migrate to the interface. The surface density of asphaltene thus increases, causing a reduction in interfacial tension. At high cation concentrations, cations strongly shield the electrostatic attraction between asphaltene and water molecules, so that the adsorption ability of asphaltenes at interface will weaken or even desorb, thus the interfacial tension elevate. Our results reveal the under

关键词： Adsorption Aggregation Asphaltenes Cations Interfacial tension Molecular dynamics

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Dissolution characteristics of mixed inorganic salts under supercritical water gasification of oily wastewater for hydrogen production

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International Journal of Hydrogen Energy 2025年 140卷 563-572页

作者： Siqi Rong Fengyuan Yang Anlan Xie Ruoyu Wang Han Jiang Pengyuan Zhao Yong Huang Yunan Chen Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an 710049 China Science and Technology on Plasma Dynamics Laboratory Air Force Engineering University Xi'an Shanxi 710038 China

In this study, the solubility characteristics of mixed inorganic chloride salts in supercritical water gasification are investigated experimentally to provide theoretical guidance for the optimization of the design of anti-blockage deposition in the SCWG process of oily wastewater and other high-salt organics. At present, there is a lack of experimental studies on the solubility of mixed inorganic salts in supercritical water, so this study investigates the solubility characteristics of mixed inorganic chloride salts containing NaCl, KCl, and CaCl 2 in supercritical water through real supercritical water experimental conditions. The solubility of the mixed inorganic chloride salts in supercritical water was analyzed in the parameter ranges of 673∼823 K and 22.5–30 MPa, mainly for the experimental conditions. It is found that the solubility of mixed inorganic salts is primarily affected by the temperature, and the solubility decreases with the increase of temperature, while the solubility of each component of mixed inorganic salts has a competitive relationship with each other, and the stronger the ionic bonding ability of inorganic salt ions, the lower the solubility of the mixed supercritical water solution. Finally, the simulation of real oil-containing wastewater with high mineralization found that the non-polarity of the supercritical water system further increased under the environment containing organic matter, which made the solubility of polar inorganic salts decrease.

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Hydrocarbon generation reaction kinetics study on supercritical water conversion of centimeter sized medium and low maturity organic-rich shale

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Petroleum Science 2025年

作者： Xie, Tian Zhao, Qiu-Yang Jin, Hui Wang, Ye-Chun Guo, Lie-Jin College of New Energy Xi'an Shiyou University Shaanxi Xi'an710065 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China

Accurate prediction of the composition of pyrolysis products is the prerequisite for achieving directional regulation of organic-rich shale pyrolysis and conversion products. In this paper, the classical segmented pyrolysis kinetics model and a new refined pyrolysis kinetics model were used to forecast the composition distribution of hydrocarbon generation products co-heated by supercritical water and medium and low maturity organic-rich shale. The prediction accuracy of the two reaction kinetics models for the composition of pyrolysis products of organic-rich shale was compared. The reaction path of hydrocarbon generation in centimeter sized organic-rich shale under the action of supercritical water was identified. The results show that the prediction accuracy of the classical segmented pyrolysis kinetics model was poor at the initial stage of the reaction, and gradually increased with increasing time. The prediction error can reach less than 25% when the reaction time was 12 h. The new refined model of reaction kinetics established is better than the classical reaction kinetics model in predicting the product distribution of pyrolysis oil and gas, and its prediction error is less than 14% in this paper. The reaction paths of hydrocarbon generation in centimeter sized organic-rich shale under supercritical water conversion mainly include organic-rich shale directly generates asphaltene and saturated hydrocarbon, asphaltene pyrolysis generates saturated hydrocarbon, aromatic hydrocarbon and resin, saturated hydrocarbon, aromatic hydrocarbon and resin polymerization generates asphaltene, and saturated hydrocarbon, resin and asphaltene generates gas. The reason for the difference of centimeter sized and millimeter sized medium and low maturity organic-rich shales hydrocarbon generation in supercritical water is that the increase of shale size promotes the reaction path of polymerization of saturated hydrocarbon and aromatic hydrocarbon to asphaltene. © 2025 The Author

关键词： Crystallization kinetics

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Water effect on ignition delay times of ethanol/iso-octane mixtures at elevated pressures

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Fuel 2025年 398卷

作者： Jiang, Xue Zhang, Tianqi Lin, Zefeng Zhang, Yingjia Huang, Zuohua Zhu, Wei Xu, Linxun Xu, Suxian State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China Shandong Chambroad New Energy Holding Development Co. Ltd. Binzhou 256600 China

The effect of water addition on the ignition delay times of ethanol/iso-octane mixtures was measured in a shock tube at pressures of 1.2 and 10 atm, temperatures from 943 to 1383 K, an equivalence ratio of 1.0, and water contents of 0 % to 40 % (mole fraction in total component). Results indicate that water addition non-monotonically affects ignition delay times at 1.2 atm, while at 10 atm, it has contrasting effects across different temperature ranges. Simulations from five representative literature models were compared with experimental data. Chemical kinetic analysis was conducted using both the Modified LLNL 2021 model and RWTH 2015 model at 10 atm and temperatures of 1300 K and 950 K. Reaction pathway analysis indicates that increased water content in the ambient enhances H-atom abstraction pathways by OH radicals during the ignition of both ethanol and iso-octane. Sensitivity analysis indicated that reactions involving hydrogen chemistry significantly influences ignition. Rate of production analysis identified consumption rates and pathways of H atom as key factors affecting temperature dependence after water addition. The fictitious diluent gas method was introduced to isolate thermal and chemical kinetics effects after water addition. © 2025

关键词： Water content

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Quantitative detection of alkali metal Na based on laser-induced breakdown spectroscopy technology

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Meitan Xuebao/Journal of the China Coal Society 2025年第4期50卷 2262-2270页

作者： Shen, Sijie Li, Chi Zhou, Wangzheng Wang, Zhenzhen Yan, Junjie Hou, Zongyu Wang, Zhe Deguchi, Yoshihiro School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Power System Operation and Control Tsinghua University Beijing100084 China Institute for Carbon Neutrality Tsinghua University Beijing100084 China Department of Energy and Power Engineering Tsinghua University Beijing100084 China Shanxi Research Institute for Clean Energy Tsinghua University Taiyuan030032 China Graduate School of Technology Industrial and Social Sciences Tokushima University Tokushima770-8506 Japan

The alkali metal compounds released from high alkali fuels such as low-quality coal during thermal utilization can affect the normal operation of thermal equipment. Therefore, rapid online detection of alkali metal content in low-quality coal is of great significance for controlling alkali metal release during combustion. The alkali metal Na element is used as the detection object, and the mixed samples of graphite and sodium chloride powder with different ratios are used as experimental samples. The influencing factors of measuring Na element in samples using laser induced breakdown spectroscopy (LIBS) technology are studied. The impact of two signal strength calculation methods on signal stability is compared. The influence of experimental parameters on signal strength and signal-to-noise ratio is analyzed. The quantitative calculation models for Na element have been established. Research has shown that the characteristic spectral lines of Na element, Na I 588.995 nm and Na I 589.592 nm, are suitable as the main analytical spectral lines. Using the area intensity of the dual line characteristic spectral lines of Na element as the signal intensity can effectively improve signal stability. When the laser energy is 60 mJ and the delay time is 1 000 ns, the relative standard deviation of spectral signal intensity is low and the signal-to-noise ratio is high. The quantitative calculation models are established using traditional calibration method, partial least squares (PLS) method, and support vector machine (SVR) with spectral signal intensity as the input and Na element addition in the sample as the output. The accuracy of each model is compared and analyzed. The results indicate that the PLS model may exhibit overfitting when the sample size is small and the input quantity is large. The fitting accuracy of the SVR model is 0.978 3, the root mean square percentage error of the training set is 13.42%, and the root mean square percentage error of the test set is 13.51

关键词： Sodium chloride

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Development of a two-phase flow solver with two-fluid model based on OpenFOAM: Validation against two-phase boiling flow

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Annals of Nuclear Energy 2025年 220卷

作者： Wu, Wenqiang Huang, Tao Du, Peng Feng, Zhenyu Zhang, Dalin Zhou, Lei Song, Gongle Deng, Jian Qiu, Zhifang Tian, Wenxi Qiu, Suizheng Su, Guanghui 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 Shaanxi Xi'an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China

The continuous advancement in computer technology and mathematical-physical models has significantly propelled the development of numerical reactor technology. There is a growing focus on high-fidelity, multi-scale, and multi-physics coupling within a unified framework. OpenFOAM, based on the finite volume method, has emerged as a promising tool for addressing this challenge. This study explores its capabilities in system-level scales, successfully developing a two-fluid, six-equation solver. The realistic closure models cover flow and heat transfer scenarios within vertical channels under pre-CHF conditions. A virtual thermal structure accounts for conjugate heat transfer between the fluid and the solid. Furthermore, the solver adheres to the discretization and solution principles within the OpenFOAM framework. The developed solver has been extensively validated against experimental data for two-phase boiling flow, with results showing good agreement, thereby demonstrating the solver's success. This work builds upon previous efforts involving the drift-flux solver and indicates that OpenFOAM can effectively handle one-dimensional or system-level scale calculations. It provides robust support for future endeavors in multi-scale and multi-physics coupling technologies. © 2025 Elsevier Ltd

关键词： Finite volume method

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