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Additional interfacial force in lattice Boltzmann models for incompressible multiphase flows

Physical Review E 2012年第2期85卷 026704-026704页

作者： Q. Li K. H. Luo Y. J. Gao Y. L. He Energy Technology Research Group School of Engineering Sciences University of Southampton Southampton SO17 1BJ United Kingdom Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China Department of Zoology University of Cambridge Cambridge CB2 3EJ United Kingdom National Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The existing lattice Boltzmann models for incompressible multiphase flows are mostly constructed with two distribution functions: one is the order parameter distribution function, which is used to track the interface between different phases, and the other is the pressure distribution function for solving the velocity field. In this paper, it is shown that in these models the recovered momentum equation is inconsistent with the target one: an additional force is included in the recovered momentum equation. The additional force has the following features. First, it is proportional to the macroscopic velocity. Second, it is zero in every single-phase region but is nonzero in the interface. Therefore it can be interpreted as an interfacial force. To investigate the effects of the additional interfacial force, numerical simulations are carried out for the problem of Rayleigh-Taylor instability, droplet splashing on a thin liquid film, and the evolution of a falling droplet under gravity. Numerical results demonstrate that, with the increase of the velocity or the Reynolds number, the additional interfacial force will gradually have an important influence on the interface and affect the numerical accuracy.

关键词： COMPUTER simulation LATTICE Boltzmann methods multiphase flow INCOMPRESSIBLE flow (Fluid mechanics) DISTRIBUTION (Probability theory) MOMENTUM (Mechanics)

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Experimental Study on the Performance Difference of Pulsating Heat Pipe Using R170 and R134a as Working Fluids

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SSRN 2023年

作者： Song, Yuxin Chen, Xi Zhan, Jingru Zhang, Hua School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China

The pulsating heat pipe (PHP), as a type of heat pipes, is a flexible heat transport device with highly efficient conduction, which is widely used in many fields including aerospace, waste heat recovery, cryogenic refrigerator and so on. The working fluids have an important effect on the thermal performance of PHPs. This study experimentally compares a PHP with R170 and R134a as the working fluids, respectively, examining temperature fluctuations, thermal resistance, and temperature differentials. Findings indicate that R170 PHP exhibits sensitivity to heat input (HI), with temperature fluctuations stagnating at 70 W. Increasing the filling ratio (FR) from 30% to 60% results in a steady rise in R170 PHP thermal resistance. While R170 PHP thermal resistance increases with higher inclination angles (IAs), it does so to a lesser extent compared to R134a PHPs. In the temperature region of -20 ℃ to 0 ℃, both R170 and R134a perform similarly. However, as the working temperature (WT) decreases, R170 PHP outperforms R134a PHP. Overall, the thermal performance of R170 PHP is superior to R134a PHP. This study provides reference value for the future research of PHPs in the temperature region of -60 ℃ to 0 ℃. © 2023, The Authors. All rights reserved.

关键词： Heat resistance

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High-Entropy (Cocrfemnni)3o4 Catalysts for Propane Catalytic Destruction: Effect of the Precipitation Agent

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SSRN 2023年

作者： Ma, Yue Zhang, Yun Jian, Yanfei Jiang, Zeyu Chai, Shouning Li, Lu Xia, Lianghui 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 Department of Physics and Information Technology Baoji University of Arts and Sciences Shaanxi Baoji721016 China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing101408 China

Efficient catalytic destruction of light alkane with ultra-stable and highly symmetric structure is still an intractable issue. High entropy oxides (HEOs) with high chemical disorder and lattice distortion and superior stability have shown great potential in heterogeneous thermocatalysis. Herein, spinel-type HEOs are synthesized via a scalable co-precipitation method with different precipitants (NaOH, Na2CO3, and NaHCO3) and firstly adopted in catalytic destruction of propane. Results demonstrate that the HEO-NaOH possesses the best activity, achieving 90% of propane conversion at 325 °C with an apparent activation energy of 56 kJ·mol-1. Compared with other two HEOs, HEO-NaOH system has larger quantities of surface oxygen vacancies and easily forming several reactive oxygen species (OOH-, O2-, and OH-, etc.), which significantly contribute to the catalytic performance. Moreover, the excellent water resistance of HEOs is verified due to their high conformational entropy and structural stability. Reaction mechanism reveals that OOH- and O2- are the key species in the oxidation of C3H8, which break C-H and C-C bonds in sequence, and are then converted to oxygenated compounds via oxygen oxidation before the final mineralization. The present work provides new insights into the fabrication of efficient catalysts for light alkane destruction as well as other thermocatalytic applications. © 2023, The Authors. All rights reserved.

关键词： Sodium hydroxide

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Effects of A‐Site Replacement (Sm, Y, and Pr) on Catalytic Performances of Mullite Catalysts for No Oxidation

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SSRN 2022年

作者： Chen, Lei Zhang, Chen Wu, Tiantian Huang, Boqiang Zhang, Jinping Guan, Guowei Zhang, Zaoxiao Hou, Xiaoke Hu, Chao Lu, Qiang School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'An710049 China School of Chemistry Xi'an Jiaotong University Xi'An710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An China National Engineering Research Center of New Energy Power Generation North China Electric Power University Beijing China

Mullite is one of the most promising NO-SCO catalyst alternatives to the commercial Pt/Al 2 O 3 , and deciphering its intrinsic properties that affecting the catalytic performance is a great challenge but critical to the development of mullite catalysts. Herein, a series of Mn-based mullite nanofibers with different A‐site cations are synthesized by electrospinning method and used for catalytic NO oxidation. Activity tests show that SmMn 2 O 5 exhibits a better NO conversion rate (77.8%) than these of PrMn 2 O 5 (63.3%) and YMn 2 O 5 (57.5%) under typical experimental conditions ( GHSV=120 000 h -1 , T =325 °C ). To investigate the factors influencing the catalytic activity, various techniques including XRD, N 2 adsorption, SEM, TEM, EDX, XPS, H 2 -TPR and O 2 -TPR are employed, and the results show that abundant surface adsorbed oxygen species and good reducibility contribute greatly to the catalytic performance of SmMn 2 O 5 . DFT calculations revealed that A-site cation played the decisive role in the Fermi level relative to the Mn 3d-band centre, thus affecting the adsorption and dissociation of O 2 molecule. The present synthetic strategy offers a new viable route for the large-scale preparation of metal oxide catalysts with remarkable NO oxidation performance for practical application. © 2022, The Authors. All rights reserved.

关键词： Positive ions

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Enhanced Hydrogen Production of Acidified Ruddlesden-Popper Type Perovskite Oxides in Water and Seawater by Coupled Piezo-Photocatalysis

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SSRN 2022年

作者： Ma, Xinyu Gao, Yangfei Yang, Bian Lou, Xiaojie Huang, Jianbing Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi'An710049 China School of Materials Science and Engineering Xi’an University of Technology Xi’an Xi'An710048 China

Photocatalytic water splitting for hydrogen production is more sustainable than traditional desalination and electrocatalysis, because of avoiding electrode corrosion and other problems. Two-dimensional perovskite oxide materials have multiple characteristics such as ferroelectric, piezoelectric and pyroelectric properties, demonstrating good light response and chemical stability, which provides a broad prospect in photo-chemical conversion. In this study, acidified La2NiO4 can greatly improve the amount of hydrogen evolution by coupling its piezocatalysis and photocatalysis. Under the full-spectrum illumination assisted with ultrasonic vibration in seawater, a recordable hydrogen production activity of 1315.44 μmol·g-1·h-1 was obtained in acidified La2NiO4 by 0.006 mol/L HCl, which more than 200 times higher than that of pure La2NiO4 (6.89 μmol·g-1·h-1) in methanol solution. It is found that the significant hydrogen production of La2NiO4 samples treated with acidification lies in the fast separation of charge carriers in comparison with those without acidification. In addition, the hydrogen production efficiency of seawater is higher than that of pure water, because the inorganic salt acts as a sacrificial agent and changes the surface charge of the catalyst. This work contributes to the in-depth understanding of piezo-photocatalysis and thus provides a new solution for improving the performance of multi-field coupling hydrogen production. © 2022, The Authors. All rights reserved.

关键词： Hydrogen production

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Enhanced Hydrogen Production of Acidified La2nio4 in Water and Seawater by Coupled Piezo-Photocatalysis

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SSRN 2022年

作者： Ma, Xinyu Gao, Yangfei Yang, Bian Lou, Xiaojie Huang, Jianbing Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi’an710049 China School of Materials Science and Engineering Xi’an University of Technology Xi’an710048 China

关键词： Hydrogen production

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Bactericidal Action of the Reactive Species Produced by Gas-Discharge Nonthermal Plasma at Low Pressure

Bactericidal Action of the Reactive Species Produced by Gas-...

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9th Asia-Pacific Conference on Plasma Science and Technology (APCPST) and 21st Symposium on Plasma Science for Materials (SPSM)第9届亚太等离子体科学与技术国际会议暨第21届等离子体材料科学研讨会

作者： H.X.Liu J.R.Chen J.L.Zhao Department of Environmental Science and Engineering Xi''an Jiaotong University Xi''an.710049.China State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an.710049.China Department of Environmental Science and Engineering Xi''an Jiaotong University Xi''an.710049.China

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On Dynamic Behavior of Triangular Shaped Cantilevers in MEMS Sensors: Effect of Curvature

On Dynamic Behavior of Triangular Shaped Cantilevers in MEMS...

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2010 10th IEEE International Conference on Solid-state and Integrated Circuit Technology(第十届固态和集成电路技术国际会议 ICSICT-2010)

作者： Guo-Ying Yuan En-Ze Huang Gui-Ming Zhang Zhuang-De Jiang Li-Bo Zhao Yong Li Zhi-Gang Liu State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 State Key Laboratory of Tribology Tsinghua University Beijing 100084 China State Key Lab of Multiple Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781424457977

A study on the effect of curvature of triangular shaped cantilevers in MEMS sensors was presented. 3-D models were performed by using the SolidWorks software. And modal analysis and harmonic response analysis were carried out on different types of geometrically configured triangular shaped cantilevers using ANSYS software. The results included the variation of natural frequencies of cantilevers and maximum equivalent von mises strain on the cantilevers with respect to radius of curvature of triangular shaped cantilevers. According to the finite element analysis results, the curvature did affect dynamic behavior of triangular shaped cantilevers in MEMS sensors. Usually, the curvature is induced by the surface stress due to microprocessing or any change of temperature, etc. Therefore, in order to achieve a steady state of strain for the MEMS sensors, it's better to eliminate the surface stress and make the cantilever transform from a curved cantilever to a straight cantilever.

关键词： CANTILEVER Curvature Surface stress Triangular Microelectromechanical systems Sensors Microtechnology Response analysis

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Experimental study on potassium catalyzed gasification of large particle size biomass with CO2

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Journal of the Energy Institute 2023年 111卷

作者： Huang, Xiaole Li, Yuhang Ren, Jiyun Yang, KaiXuan Li, Ruiyu Bai, Yang Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China Xi'an Thermal Power Research Institue Co. Ltd. Xi'an710032 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai 200240 China Shunde Institue of Inspection Guangdong Institue of Special Equipment Inspection and Research Foshan528300 China

Candlenut wood with large particle size is selected to investigate the biomass gasification catalyzed by potassium. The sample pore structure, the spatial distribution of potassium, and the effects of potassium salt species on the biomass gasification with CO2 are examined. The results show that the large particle candlenut wood exhibits obvious spatial anisotropy and that the pore structure is mainly distributed along the axial direction. Large particle candlenut wood has a more uniform distribution of potassium salts along the axial direction. Part of the potassium salt releases outward during the gasification, which reduces the potassium salt content in the sample center. The average potassium contents of sample loaded with KCl and biochar of sample loaded with KCl are 9.273% and 7.745%, respectively. The synthesis of polycyclic aromatic hydrocarbons in tar could be inhibited by potassium, which could also catalyze the gasification and methane removal reactions of biochar and facilitate the formation of CO and H2. Compared to raw sample (28.99%), the syngas yields from the gasification of sample loaded with KCl, sample loaded with K2CO3, and sample loaded with K2SO4 are 40.22%, 52.16%, and 41.72%, separately. The catalysis of potassium is closely related to its occupation of the active sites on biochar. The chemical bonds formed by potassium and biochar are repeatedly broken and formed during the gasification, which promotes the decomposition of organic matter. Compared with KCl and K2SO4, K2CO3 has a better catalytic effect. © 2023 Energy Institute

关键词： Biomass

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Prediction of Pressure Drop in Heavy Oil-Water Ring Two-Phase flow Based on Modified Two-Fluid Model

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SSRN 2024年

作者： Fu, Jiqiang Du, Mingjun Jing, Jiaqiang Sun, Jie Liu, Huichao Chen, Yongjiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Petroleum Engineering & Construction Corp North Company Heibei Renqiu062552 China School of Oil & Natural Gas Engineering Southwest Petroleum University Sichuan Chengdu610500 China

Accurate prediction of pressure drop of the heavy oil-water ring flow in pipeline is of great significance for establishing an optimal drag reduction model and ensuring safe production. The effects of different factors on the flow pattern and pressure drop of heavy oil-water annular two-phase flow were systematically analyzed, and a standard two-fluid pressure drop prediction model for annular flow was established. By modifying the shear stress equation of oil-water interface and introducing the wave-flow theory to modify the shear stress equation of water wall, a pressure drop prediction model for the generalized concentric water ring was obtained to calculate the periodic fluctuations of oil phase. Furthermore, by introducing the comprehensive Reynolds number expression of eccentric water ring, the pressure drop prediction model for the generalized eccentric water ring was obtained to calculate the periodic fluctuations of oil phase. The results show that the pressure drop prediction accuracy of the concentric water ring for ultra-heavy oil is improved by 80 % by using the modified pressure drop prediction model. The comprehensive Reynolds number expression of eccentric water ring can effectively reflect the influence of eccentric effect on shear stress of water wall and the calculation error is less than 20 % by predicting the pressure drop of the generalized eccentric water ring with different density differences. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

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