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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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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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Flocculation of suspended cohesive particles in Rayleigh-Bénard turbulence

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Physical Review Fluids 2025年第2期10卷 024305-024305页

作者： Han Huang Shuaiqi Zhao Rui Zhang Binbin Pei Kunpeng Zhao Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Key Laboratory of Mechanics on Disaster and Environment in Western China The Ministry of Education of China Lanzhou University Lanzhou 730000 China

We employ a four-way coupled numerical approach to investigate the dynamics of suspended cohesive particles in Rayleigh-Bénard turbulence. The Stokes drag, cohesive, and direct contact forces between primary particles are captured in detail, yielding the phenomena of flocs' aggregation, breakage, and deformation. The momentum and thermal exchange between primary particles and the fluid are considered based on the Source-in-Cell method. We found that the initial increase of the average floc size indicates a temporary flocculation phase, which is followed by an equilibrium phase where the average floc size becomes stable, reflecting the balance between aggregation and breakage. Different from the traditional perspective, which attributed the local accumulation of particles to their gravity, we found that the suspended particles still tend to accumulate in the bottom hot boundary layer region. This accumulation is primarily driven by the temperature-induced variation in aggregation strength and the nonuniform spatial distribution of floc inertia. Additionally, the stronger cohesion yields a reduction in momentum intensity of the thermal plumes, primarily due to the more pronounced weakening of fluid momentum by the larger flocs.

关键词： Momentum

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Operational flexibility enhancement of a combined heat and power plant supplying industrial steam: The integration of sensible or sensible-latent heat storage system

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Journal of Energy Storage 2025年 117卷

作者： Tang, Haiyu Liu, Ming Zhang, Kezhen Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Xi'an Thermal Power Research Institute Co. Ltd. Xi'an710054 China

The increasing penetration of renewable energy requires greater operational flexibility of thermal power plants, as dispatchable power sources are essential to balance the power supply and demand sides. However, the CHP plant has restricted load cycling range due to its heat dominated operation mode. The Integration of a high-temperature heat storage system is a potential solution to enhance the operational flexibility of the CHP plant that cogenerates industrial steam and power. However, the optimal design of the heat storage system integrated within a CHP plant is complicated due to the changing operation conditions and various heat exchanging mediums. In this study, the design method of the sensible or sensible-latent heat storage system integrated with a CHP plant supplying industrial steam was proposed. The simulation, exergy analysis and economic analysis models were developed, and a case study of 350 MW CHP plant was conducted. The maximum CHP plant output power decrement is 13.59 MW when the heat of flue gas and main steam is stored in the sensible or sensible-latent heat storage system. The exergy-to-exergy efficiencies of sensible and sensible-latent heat storage systems are 71.60 % and 77.76 %, respectively. However, the economic analysis results show that the sensible heat storage system is more cost-effective than the sensible-latent heat storage system. © 2025 Elsevier Ltd

关键词： Latent heat

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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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Effect of Surfactant Concentration on the Behavior of Single Oxygen Bubble in Photoelectrochemical Water Splitting

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Langmuir 2025年

作者： Yang, Zihan Xu, Qiang Luo, Xinyi Nie, Tengfei Li, Jinfeng Wang, Mengsha Guo, Liejin Jiangxi Provincial Key Laboratory of Particle Technology Jiangxi University of Science and Technology Ganzhou341000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The control of bubble growth and departure during the process of photoelectrochemical water splitting is crucial for enhancing gas production efficiency. By introducing varying concentrations of surfactants into the electrolyte and using a synchronous measurement system, we examined how the change in surfactant concentration affects bubble nucleation and growth characteristics. The results indicate that bubbles’ critical nucleation potentials initially decrease and subsequently increase with increasing surfactant concentration, reaching a minimum value when the concentration is 1 × 10-7 M. In contrast, bubble growth periods and departure diameters reach their maximum values. Further analysis shows that the gas production rate and the average gas evolution efficiency reach their maximum when the surfactant concentration is 1 × 10-7 M, indicating that adding an appropriate amount of surfactant is advantageous for gas production. In addition, a force equilibrium model incorporating the Marangoni force at various surfactant concentrations was developed to predict oxygen bubbles’ departure diameter. The predicted values exhibit excellent concurrence with the experimental data. The solutal Marangoni force is the primary determinant that affects bubble departure diameter when the surfactant concentrations are below approximately 4 × 10-6 M, while the thermal Marangoni force assumes precedence when concentrations exceed about 4 × 10-6 M. © 2025 American Chemical Society.

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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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Chromium Promoted the Efficient and Stable Catalytic Degradation of Propane Over Pt/Hzsm-5 Catalyst: Optimization and Reaction Mechanism

SSRN

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SSRN 2025年

作者： Jian, Yanfei Xu, He Wang, Yao Wang, Jingjing Xia, Lianghui Liu, Yujie Yu, Yanke He, Chi State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China National Engineering Laboratory for VOCs Pollution Control Material and Technology University of Chinese Academy of Sciences Beijing101408 China Yunnan University China

Light alkanes are a class of ubiquitous volatile organic compounds (VOCs), which bring great environmental hazards and health risks. However, low-temperature degradation of light alkanes is still a great challenge. Herein, a series of Pt/HZSM-5 catalysts without/with additives of Cr were fabricated. Catalytic performance of the catalyst for C3H8 low temperature combustion was investigated. It was found that Cr element had a significant effect on the activity of Pt/HZSM-5. Pt/Cr1/HZSM-5 performed the best activity for C3H8, excellent high temperature stability and water resistance. Characterization results of catalysts indicated that the introduction of Cr element could fix Pt site to promote the dispersion of Pt on the support. Moreover, the interaction between Cr and Pt produced more active Pt species, surface active lattice oxygen and acidic sites, which could promote the activation of C-H bonds in C3H8. Theoretical calculations showed that the interface between Pt and Cr had stronger adsorption for O2 and C3H8, which could accelerate propane oxidation. In this study, the effect of transition metal elements on the promotion of noble metal catalysts in the low-temperature degradation of light alkanes was discussed in depth, and it provided a reference for the design of efficient noble metal molecular sieve catalysts. © 2025, The Authors. All rights reserved.

关键词： Molecular sieves

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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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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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