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The influence of peak wave-channel clearance on performance characteristics of traveling wave pump

Energy 2025年 325卷

作者： Li, Gucheng Zhu, Qianming Gu, Qingqing School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

Pumped storage plays a significant role in addressing the intermittency associated with solar and wind energy. The research on pumped storage is vital for sustainable development, with the pump serving as a key component. Achieving efficient energy conversion necessitates advancements in pumped storage technology, specifically through the development of novel pump designs that overcome limitations such as cavitation and vibration associated with conventional pumps. This study introduces a traveling wave pump that utilizes a traveling wave motion mechanism within a vertical rectangular flow channel to lift water to higher elevations. A simplified two-dimensional traveling wave plate model is employed to examine the influence of peak wave-channel clearance on pump performance using numerical simulations. The findings indicate that reducing the clearance causes a linear increase in time-averaged efficiency and a corresponding decrease in volumetric loss. Under high head conditions, pump performance is particularly sensitive to variations in clearance. A reduction in clearance accelerates high-speed fluid flow above the contraction point while reducing the low-speed zone below it. Furthermore, it weakens the intensity of the high-speed vortex at the leading edge of the traveling wave plate and the leakage vortex beneath the contraction point. © 2025 Elsevier Ltd

关键词： Vortex flow

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On revised mixture fraction describing multi-stream mixing

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Combustion and Flame 2025年 277卷

作者： Wang, Ziqi Zhang, Weijie Huang, Hai Wang, Jinhua Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Multi-stream mixing is common in practice but cannot be modeled using the traditional Bilger mixture fraction defined for only two streams. This work was intended to define the multi-stream mixture fractions that can be adopted in flamelet-tabulated combustion models to simulate the multi-stream mixing and combustion. These mixture fractions are expressed as linear combinations of species mass fractions like the Bilger mixture fraction. The present definition is special as the new mixture fractions are nonconservative and can include the preferential diffusion (PD) effects which were often ignored before. Meanwhile, it can be appliable for any number of inlet streams. The multi-stream mixture fractions are derived based on some basic conserved scalars, like the element mass fractions, enthalpy, and transported scalars. Governing equations for the multi-stream mixture fractions are also presented. © 2025 The Combustion Institute

关键词： Volume fraction

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Experimental Study on Heat Transfer Characteristics of Supercritical Carbon Dioxide in a Vertical Circular Tube

SSRN

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SSRN 2025年

作者： Yang, Haikuo Nie, Ruishan Zhang, Kui Tian, Wenxi State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Supercritical carbon dioxide (S-CO2) nuclear energy and power systems have garnered significant attention for flow and heat transfer experiments because of their compact design, advanced circulation methods, and high thermal efficiency, aligning with future trends in nuclear power plant development. However, the dramatic change in physical properties of S-CO2 near its pseudo-critical point can lead to heat transfer deterioration (HTD) in heat exchangers, potentially damaging the S-CO2 Brayton system. This paper presents an experimental study on the HTD of S-CO2 in a vertical circular tube under forced circulation, examining how heat flux, inlet temperature, and system pressure influence *** analysis delves into the mechanisms of HTD, focusing on the buoyancy and flow acceleration effects. Additionally, the study explores the impact of heat flux and system pressure on S-CO2 natural circulation. Ultimately, the research summarizes the flow and heat transfer characteristics of S-CO2 and proposes a new heat transfer correlation formula, demonstrating an error margin within ±25%, which meets practical engineering requirements. This experimental study contributes valuable data to the understanding of flow and heat transfer phenomena in S-CO2, offering significant insights for future applications. © 2025, The Authors. All rights reserved.

关键词： Nuclear energy

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

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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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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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