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Dye visualization of the wake of a near-wall particle in response to a periodic oscillation

Measurement: Sensors 2021年 13卷

作者： Li, Xing Zhang, Haibin Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'anShaanxi710049 China

In turbulent dispersed multiphase flows, the interaction between the particle wake and the ambient turbulent fluctuation can be crucial for the change of the multiphase system. This issue is extremely complex due to the chaotic nature of the turbulence. In this paper, the ambient turbulent fluctuation of certain frequency is simulated by the Karman vortex street behind a horizontally placed cylinder, and the response of the wake of a stationary near-wall particle to the oncoming oscillation is investigated. The dye visualization is used to mark the vortex structures of the wake and the oncoming oscillation, respectively, and power spectrum analysis is conducted to reveal the features in the frequency domain. Results show that at relatively low Rep, the oncoming oscillation has little effect on the wake. As Rep increases, the response of the wake to the oncoming oscillation is evident. High-frequency fluctuation dissipates very fast and only exists near the particle. On the contrary, the life span of the low-frequency fluctuation lasts for a much longer period and exists far downstream. In addition, the self-induced vortex shedding is not notable and is overwhelmed by the oncoming oscillation. © 2020 The Author(s)

关键词： Wakes

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Multi-Objective Optimization Design of a Solar-powered Integrated Multi-Generation System Based On Combined Sco 2 Brayton Cycle and Orc Using Machine Learning Approach

SSRN

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SSRN 2024年

作者： Zhang, Junyi Wang, Jiangfeng Liu, Wenxing Hu, Bin Lou, Juwei Zhao, Pan Institute of Turbomachinery State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Nuclear Power Institute of China No. 328 Section 1 Changshun Avenue Sichuan Chengdu610213 China DongFang Electric Engineering& Consulting Co. Ltd 18 Xixin Avenue High-tech West Zone Sichuan Chengdu611731 China

With the rapid development of technology and the accelerated degradation of the global environment, there is an urgent need to find a clean and efficient energy solution to replace traditional fossil fuels for energy production. Additionally, this solution should also meet the growing demand for various energy products for energy user. In particular for remote areas such as islands, coastal regions and deserts which are far from the power grid, regular resources such as power, freshwater, and cooling are all scarce. Therefore, integrating freshwater and cooling subsystems into the power generation system to create a multi-generation system can facilitate achieving energy self-sufficiency in remote regions. This paper proposes an integrated multi-generation system powered by a solar power tower (SPT) according to the principle of cascading energy utilization, which includes a supercritical CO2 (SCO2) Brayton cycle, an Organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), and a reverse osmosis (RO) unit. A mathematical model is established to analyze the system performance from the perspectives of energy, exergy and economics. Different machine learning algorithms including back propagation neural network (BPNN), support vector regression (SVR), random forest (RF) are used to develop prediction models of the system performance. By comparing and analyzing the predictive performance of different machine learning models, the optimal machine learning model is obtained as a surrogate model for the thermodynamic model of the proposed system to accelerate the optimization process. The results show that the BPNN model demonstrates the highest predictive accuracy and the lowest relative error fluctuation, maintaining a relative error of less than 1% for over 97.5% of the data in the testing set. When comparing the multi-objective optimization results of the BPNN model with those of the thermodynamic model from multiple perspectives, it can be observed that the res

关键词： Neural network models

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Zif-8 Loaded Ag/Zno Electrospun Nanofibers Enabling High-Performance H2 Gas Sensing for Battery Safety Early Warning

SSRN

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SSRN 2024年

作者： Wang, Ze Zhu, Lei Zhang, Jiaxin Wang, Jingzhao Cui, Xiangming Chen, Xin Liu, Wenbiao Ma, Hang Wang, Jianan Yan, Wei Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an710049 China School of Physics and Electrical Engineering Weinan Normal University Chaoyang Street Weinan714099 China Center of Research & Development Yunnan Yuntianhua Co. LTD 1417 Dianchi Road Kunming650228 China

Safety issues triggered by battery thermal runaway have become the most crucial obstacle to the future development of the high-energy-density energy storage systems. As hydrogen (H2) will be inevitably generated along with heat release caused by the side reactions in the early stages of battery thermal runaway, rapid monitoring of trace H2 is considered as an effective measure enabling the battery safety early warning. Herein, to develop high-performance H2 sensing materials to monitor of low-concentration H2 leakage, ZIF-8 loaded Ag/ZnO electrospun nanofibers (ZAZ NFs) were designed by electrospinning and self-sacrificial template methods. Benefiting from all the enrichment and sieving effects of ZIF-8 shell, the catalytic and sensitization effects of Ag and abundant active sites provided by Ag and ZIF-8 loading, the ZAZ sensor enables ppb-level limit of detection toward H2, fast response (9 s), high selectivity and excellent humidity resistance (36.1 to 100 ppm H2 at 95% RH). Furthermore, this ZAZ sensor also enabled the safety early warning (67.79 s before battery bulge) for practical pouch lithium cells, highlighting its great application potential in future advanced battery safety management system. © 2024, The Authors. All rights reserved.

关键词： Organometallics

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Investigations on affinity law under gas–liquid conditions in multistage radial and mixed-flow multiphase pumps

International Journal of Fluid Engineering

引用

International Journal of Fluid engineering 2024年第1期1卷 56-70页

作者： Liang Chang Chenyu Yang Xiaobin Su Xiaoyu Dai Qiang Xu Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Affinity laws have been widely used in pump design and simulation under high-temperature and corrosive *** applying such laws,it is possible to shorten development cycles and reduce test ***,current applications of affinity laws are still limited to liquid *** this paper,expressions for affinity laws and their applicability are investigated for multistage radial and mixed-flow multiphase pumps under gas–liquid conditions.A high-pressure(30 MPa)gas–liquid experimental platform is constructed,and three-stage and 25-stage radial pumps and a 15-stage mixed-flow pump are investigated,with specific speeds of 107 and *** gas compressibility taken into account,the gas–liquid two-phase flow rate,head,and power,and the corresponding dimensionless hydraulic coefficients,are defined for multiphase *** deterioration of gas–liquid pressurization performance is found to be divided into three processes with different dynamic mechanisms,corresponding to three flow *** inlet gas volume fraction of pump is used to judge dynamic *** the same inlet gas volume fractionsλ_(1)=λ_(2),when the gas–liquid flows in two pumps have the same flow pattern,dynamic similarity will be *** affinity law that is established shows good applicability to the three-stage radial multiphase pump,with goodness of fit R^(2)larger than 0.9 for the two-phaseΨ_(m)–Φ_(m)andΠ_(m)–Φ_(m)performance ***,experimental results indicate that the affinity law also has good applicability to multiphase pumps with different stage numbers and blade structures under gas–liquid conditions.

关键词： flow law radial

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Experimental investigation on the vibration characteristics induced by severe slugging in a pipeline S-shaped riser system

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Journal of Fluids and Structures 2025年 137卷

作者： Yuwen Li Qiang Xu Yeqi Cao Bo Huang Haiyang Yu Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China

The investigation of the severe slugging characteristics and its induced vibration is an important basis for effectively avoiding fatigue damage or excessive stress in the offshore riser system. In this paper, a non-invasive optical method is used to study the vibration induced by severe slugging in a pipeline S-shaped riser system. Based on the image data of the gas-liquid interface structure and differential pressure fluctuation, severe slugging is classified into three sub-flow patterns (SS1, SS2, and SS3), and the flow characteristics and dynamic response of the riser are investigated at three sub-flow patterns. The two peaks in the spectral of the riser vibration response correspond to the fluctuation frequency of the differential pressure and the first natural frequency of the riser, respectively, and then a correlation for predicting the response frequency induced by severe slugging is established. The vibration amplitude of the riser is strongly related to the bubble length and the liquid slug velocity in the gas blowdown stage. The in-plane vibration responses of the riser are dominated by the first and second modes. The two modes coexist and switch over time due to the continuous change of slug characteristic parameters.

关键词：

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flow and residence time distribution characteristics in continuous hydrothermal reactor under different heating schemes

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Chemical engineering Science 2025年 316卷

作者： Yi Li Junying Wang Xiaoyu Li Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi 710049 PR China

Residence time distribution (RTD) is of significance for reflecting materials or intermediate products dispersion and actual reaction time inside continuous hydrothermal reactors of supercritical water gasification technology. Generally, RTD is strictly related to flow field, which can be affected by wall heating schemes. In order to propose methods to regulating RTD, effects of different heating schemes on flow and RTD characteristics are investigated and compared by numerical simulation. The results indicate that increasing heat flux, interrupting boundary flow by interlace heating, and setting cooling walls can significantly regulate RTD. By analyzing the correspondence of flow and RTD, the mechanisms of increasing materials and intermediate products dispersion can be attribute to the increase of flow instability and the generation of additional vortices. For example, in the cases of present work, the narrow-strip double-vortex generated by mixing between thermal boundary flow and branch flow may significantly increase average residence time and materials distribution range from 10.93 s and 1.00 to 22.83 s and 1.51. In the region above branch inlet without time-averaged vortex structure, the increasing of flow instability caused by wall heating is observed to widen materials distribution range from 0.75 to 0.99. Heating scheme customized according to these mechanisms can regulating RTD as expected, proving the feasibility and significance of regulating RTD by heating schemes.

关键词： Reaction intermediates

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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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Investigations on affinity law under gas-liquid conditions in multistage radial and mixed-flow multiphase pumps

国际流体工程（英文）

引用

国际流体工程（英文） 2024年第1期1卷 52-66页

作者： Liang Chang Chenyu Yang Xiaobin Su Xiaoyu Dai Qiang Xu Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Affinity laws have been widely used in pump design and simulation under high-temperature and corrosive *** applying such laws,it is possible to shorten development cycles and reduce test ***,current applications of affinity laws are still limited to liquid *** this paper,expressions for affinity laws and their applicability are investigated for multistage radial and mixed-flow multiphase pumps under gas-liquid conditions.A high-pressure(30 MPa)gas-liquid experimental platform is constructed,and three-stage and 25-stage radial pumps and a 15-stage mixed-flow pump are investigated,with specific speeds of 107 and *** gas compressibility taken into account,the gas-liquid two-phase flow rate,head,and power,and the corresponding dimensionless hydraulic coefficients,are defined for multiphase *** deterioration of gas-liquid pressurization performance is found to be divided into three processes with different dynamic mechanisms,corresponding to three flow *** inlet gas volume fraction of pump is used to judge dynamic *** the same inlet gas volume fractions λ1=λ2,when the gas-liquid flows in two pumps have the same flow pattern,dynamic similarity will be *** affinity law that is established shows good applicability to the three-stage radial multiphase pump,with goodness of fit R2 larger than 0.9 for the two-phaseΨm-Φm andΠm-Φm performance ***,experimental results indicate that the affinity law also has good applicability to multiphase pumps with different stage numbers and blade structures under gas-liquid conditions.

关键词： conditions radial affinity gas-liquid investigations mixed-flow multiphase multistage pumps under

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Catalytic combustion of methane over a highly active and stable Ni0/Ce02 catalyst

引用

Frontiers of Chemical Science and engineering 2020年第4期14卷 534-545页

作者： Xiuhui Huang Junfeng Li Jun Wang Zeqiu Li Jiayin Xu School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China Shanghai MCC20 Construction Co.Ltd Shanghai 201999China

In the last decades,many reports dealing with technology for the catalytic combustion of methane(CH4)have been ***,attention has increasingly focused on the synthesis and catalytic activity of nickel *** this paper,a NiO/CeO2 catalyst with high catalytic performance in methane combustion was synthe-sized via a facile impregnation method,and its catalytic activity,stability,and water-resistance during CH4 com-bustion were investigated.X-ray diffraction,low-tempera-ture N2 adsorption,thermogravimetric analysis,Fourier transform infrared spectroscopy,hydrogen temperature programmed reduction,methane temperature programmed surface reaction,Raman spectroscopy,electron paramag-netic resonance,and transmission electron microscope characterization of the catalyst were conducted to determine the origin of its high catalytic activity and stability in *** incorporation of NiO was found to enhance the concentration of oxygen vacancies,as well as the activity and amount of surface *** a result,the mobility of bulk oxygen in CeO2 was *** presence of CeO2 prevented the aggregation of NiO,enhanced reduction by NiO,and provided more oxygen species for the combustion *** results of a kinetics study indicated that the reaction order was about 1.07 for CH4 and about 0.10 for O2 over the NiO/CeO2 catalyst.

关键词： methane combustion NiO/CeO2 catalyst interaction oxygen vacancy kinetic study

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Experimental Study of Liquid Immersion Cooling for Different Cylindrical Lithium-Ion Batteries Under Rapid Charging Conditions

SSRN

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SSRN 2022年

作者： Li, Yang Bai, Minli Zhou, Zhifu Lv, Jizu Hu, Chengzhi Gao, Linsong Peng, Chunyang Li, Yulong Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

In this study, the fluorinated liquid immersion cooling scheme has been proposed and tested for cooling the six different types of cylindrical lithium-ion batteries (LIBs) under fast charging conditions. SF33, with the boiling point of 33.4 °C, is chosen as the fluorinated liquid for the immersion cooling. Firstly, the voltage and temperature responses of LIBs under fast charging conditions with natural convection and SF33 immersion cooling were explored. It is found that the SF33 immersion cooling has a significant advantage over natural convection on controlling the battery temperature, thus ensuring the stability and safety of LIBs in the fast charging process. Subsequently, the high-speed photography was used to observe the bubble behaviors in the cooling process of SF33, and the heat transfer mechanism in the two-phase heat transfer process corresponding to immersion cooling of LIB was preliminary analyzed and discussed. It can be concluded that when the charging current is higher, the phenomenon of subcooled boiling as well as saturation boiling is generated in the SF33. The transition from single-phase convective heat transfer to boiling heat transfer greatly increases the heat transfer coefficient. © 2022, The Authors. All rights reserved.

关键词： Liquids

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