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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryton Cycle Coaxial Integrated Unit

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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryto...

Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Xiaokang Xu Yi Yang Jiangfeng Wang Juwei Lou Liangqi Chen State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and Technology National University of Defense Technology Changsha China

The rotor system plays a very important role in supercritical carbon dioxide Brayton cycle system, and its dynamic problem will directly affect the motion stability and safety of the whole unit. In this paper, the rotor dynamic model of supercritical CO 2 coaxial unit is established by finite element method, and the critical speed, modal shape and unbalance response of the rotor are studied. The first seven critical speed of the rotor and the first seven natural frequency of the rotor at the working speed are calculated. The bending modal of the rotor and the position where the rotor amplitude is the largest are analyzed, which can provide reference for the optimization design of the rotor stability. The influences of mass unbalances at the operational speed of rotor are analyzed. The research can provide some suggestions for the optimal design and actual operation of the supercritical CO 2 coaxial integrated unit.

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Navigating the Dual Pathways of Ion Removal in flow-Electrode Capacitive Deionization: Capacitive Trapping vs. Electrodialytic Migration

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SSRN 2025年

作者： Gu, Haibo Hou, Chengsi Mao, Yunfeng Wu, Deli School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science & Engineering Tongji University Shanghai200092 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Shanghai Institute of Pollution Control and Ecological Security Shanghai200092 China

By introducing flowing electrodes, FCDI enables desalination through dual mechanisms of electrodialytic and capacitive effects. Clarifying their distinct roles is essential to advance tailored system design and performance enhancement. This work elucidates the antagonistic interplay between capacitive trapping and electrodialytic migration in flow-electrode capacitive deionization (FCDI) through both electrochemical characterization and multiphysics modeling. Experimental analyses reveal that elevated flow rates enhance electrodialytic migration but impair capacitive adsorption. Multivariate parametric studies demonstrate that capacitive dominance prevails at high current densities and low electrolyte concentrations, whereas electrodialytic effects peak under high electrolyte concentration and moderate flow rates. The balance between the effects of electrodialysis (ED) and capacitive deionization (CDI) is greatly impacted by convective mass transfer, which is caused by the electrode flow rate. While higher solid weight percentages in the flow electrode improve the CDI effect by increasing the number of active sites for salt adsorption, increased electrode flow rates maximize the ED effect by encouraging ion transport in the electrolyte. In short words, strategies to promote free ions dispersing in the electrolyte would enhance the electrodialytic contribution, whereas the concentration polarization would benefit the capacitive contribution. This work opens the door for the exploration of upgrading FCDI architectures and optimizing operation parameters while providing insights into the intricate interactions within the system. © 2025, The Authors. All rights reserved.

关键词： Desalination

Experiments and predictions for severe slugging of gas-liquid two-phase flows in a long-distance pipeline-riser system

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Ocean engineering 2024年 301卷

作者： Chang, Yingjie Xu, Qiang Zou, Suifeng Zhao, Xiangyuan Wu, Quanhong Wang, Yechun Thévenin, Dominique Guo, Liejin Shaanxi Key Laboratory of New Transportation Energy and Automotive Energy Saving Chang'an University Xi'an710064 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg Magdeburg39106 Germany

Experiments concerning the flow regimes observed in gas-liquid two-phase flows in a long-distance pipeline-riser system were carried out and analyzed in this paper. The test loop with 0.075 m inner diameter consisted of a 314 m horizontal pipeline, followed by a 25 m downward-inclined pipe, and finally a 21.5 m riser pipe. An industrial-scale global flow regime map including 5 flow regimes was derived from differential pressure measurements in the riser and was used as a reference for improvements. Electrical capacitance volume tomography installed in the horizontal section was used to reconstruct the phase interface and calculate the average gas void fraction (GVF). An appropriate model for this system was selected by comparing the experimental GVF with different, widely used models. The occurrence of severe slugging flow (SS) can be predicted accurately using an improved model involving additional corrections that consider pipeline length, accurate GVF calculation, and gas density. This study supports the development of a suitable SS prediction model enabling safe design, operation, and control of practical systems. © 2024 Elsevier Ltd

关键词： Pipelines

Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus

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Simulation Study on Heat Exchangers Characteristics of Solar...

Algorithms, High Performance Computing and Artificial Intelligence (AHPCAI), International Conference on

作者： Pengfei Chen Kang Chen Huaiwu Peng Yanlong Zhang Baercheng Bawaa Qiuyang Zhao Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises.

关键词： Water Temperature Costs Oils Simulation Water heating Solar heating

Transient Analysis of Cryogenic Cooling Performance for High-power Semiconductor Lasers Using Flash-Evaporation Spray

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SSRN 2022年

作者： Tian, Jiameng Li, Bufa Wang, Junfeng Chen, Bin Zhou, Zhifu Wang, Hai School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Focusing on the cryogenic cooling for the high-power semiconductor lasers to improve their output performance, this work conducted an experimental investigation on analyzing the transient cooling performance using a pulsed two-phase flash-evaporation spray with the environmental cryogen R32. A heat flux estimation methodology that considers an imposed heat flux as a boundary condition, was first developed to assist the transient heat transfer analysis. The results provided further insight into phase-change heat transfer on the hot surface from high-temperature to cryogenic regimes through coupling the heat transfer measurements with observations of hydrodynamic liquid film formation and development. The moderate spurt duration (Δ t = 30 s) that produced a large temperature drop (109.5 °C) and high time-averaged cooling rate (24.1 W/cm2) was preferable. The significant losses in droplets’ momentum and mass contributed to the fast decrease in cooling effect as spray distance (Z) increased. Specifically, shortening Z from 50 to 10 mm not only increased the maximum surface heat flux from 19.6 to 73.6 W/cm2, but also broadened the temperature region with high heat flux. The nozzle with a smaller orifice diameter (0.5 mm) produced a lower cooling rate. Whereas surprisingly, its lower flow rate resulted in the lesser coolant accumulation and splashing on the hot surface, which elevated its thermal efficiency. Spurt duration that can produce a specific temperature drop almost remained unchanged or slightly raised as the input heating power increased, implying that the fluid supply is excess and the liquid flow rate could be reduced to save liquids. © 2022, The Authors. All rights reserved.

关键词： Heat flux

Analysis on the Thermal Behaviour of the Latent Heat Storage System Using S-Co2 and H-Pcm

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SSRN 2022年

作者： Nan, Wenguang Ming, Zhu Wang, Yueshe School of Mechanical and Power Engineering Nanjing Tech University Nanjing211816 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Energy storage and utilization of CO2 have attracted increasing attention due to international zero carbon plan. Here, the latent heat storage system using high-temperature phase change material (H-PCM) and supercritical CO2 (S-CO2) is analysed by using CFD simulation, in which the tube containing S-CO2 is submerged in a tank containing the salt with high melting temperature. A new and combined phase transition model is developed to describe the dynamics of PCM in different phase state, and it is validated against experimental data in literature. The dynamics of natural convection is focused, and its effects on the heat storage system are analysed, including maximum natural convection velocity, phase interface, and melting pattern. The results show that natural convection has a great influence on the melting process of the H-PCM in the charging process. The melting pattern of H-PCM could be contrary between the cases with and without considering natural convection. During the discharging process, natural convection has little effect on the heat transfer of energy release due to its short duration. With the increase of ratio between the S-CO2 tube and H-PCM tank, the strength of the natural convection of melting H-PCM is enhanced, especially the duration of natural convection. © 2022, The Authors. All rights reserved.

关键词： Natural convection

A kinetics and dynamics study on the auto-ignition of dimethyl ether at low temperatures and low pressures 38th

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A kinetics and dynamics study on the auto-ignition of dimeth...

38th International Symposium on Combustion, 2021

作者： Huang, Wenlin Zhao, Qian Huang, Zuohua Curran, Henry J. Zhang, Yingjia State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Combustion Chemistry Centre School of Chemistry Ryan Institute MaREI Nui Galway Ireland

Dimethyl ether (DME)/air mixtures at various equivalence ratios from lean (0.5) to extremely rich (5.0) were ignited behind reflected shock waves at a fixed pressure (3.0 atm) over the temperature range 625 K– 1200 K. The ignition behavior was different from that at high-pressures, with a repeatable ignition delay time fall-off feature observed experimentally in the temperature transition zone from the negative temperature coefficient (NTC) regime to the high-temperature regime. The fall-off behavior showed strong equivalence ratio dependence and disappeared completely at an equivalence ratio of 5.0. A local ignition kernel postulate was implemented numerically to quantifiably examine the inhomogeneous premature ignition. At low temperature, no pre-ignition occurs in the mixture. A conspicuous discrepancy was observed between the measurements and constrained UV simulations at temperatures beyond the NTC regime. A third O₂ addition reaction sub-set was incorporated into AramcoMech 3.0, together with related species thermochemistry calculated using the G3/G4/CBS-APNO compound method, to explore the low-temperature deviation. The new reaction class did not influence the model predictions in IDT, but the updated thermochemistry does. Sensitivity analyses indicated that the decomposition of hydroperoxy-methylformate plays a critical role in improving the low-temperature oxidation mechanism of DME.

关键词： Ethers

Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

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Energy & Environmental Materials 2021年第3期4卷 434-443页

作者： Yuhan Li Zongjie Sun Dongyu Liu Shiyao Lu Fei Li Guoxin Gao Min Zhu Mingtao Li Yanfeng Zhang Huaitian Bu Zhiyu Jia Shujiang Ding Department of Applied Chemistry School of ChemistryXi’an Key Laboratory of Sustainable Energy Materials ChemistryMOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterState Key Laboratory of Electrical Insulation and Power EquipmentXi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Materials and Nanotechnology SINTEF IndustryForskningsveien 1Oslo 0373Norway School of Chemistry and Chemical Engineering MOE Key Laboratory of Cluster ScienceBeijing Institute of TechnologyBeijing 100081China

The development of metallic lithium anode is restrained by lithium dendrite growth during *** solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite *** prepare the high-performance solid polymer electrolyte,the environment-friendly and cheap bacterial cellulose(BC)is used as filler incorporating with PEO-based electrolyte owing to good mechanical properties and Li salts ***/Li TFSI/BC composite solid polymer electrolytes(CSPE)are prepared easily by aqueous mixing in *** lithium ion transference number of PEO/Li TFSI/BC CSPE is 0.57,which is higher than PEO/Li TFSI solid polymer electrolyte(SPE)(0.409).The PEO/Li TFSI/BC CSPE exhibits larger tensile strength(4.43 MPa)than PEO/Li TFSI SPE(1.34 MPa).The electrochemical window of composite electrolyte is widened 1.43 V by adding *** functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed,suggesting the enhanced lithium ion *** molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite *** solid-state Li metal battery with PEO/Li TFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/Li TFSI SPE battery(50 cycles).Li symmetrical battery using PEO/Li TFSI/BC CSPE could be stable for 1160 h.

关键词： all solid-state battery bacterial cellulose composite polymer electrolyte DFT calculations HOMO and LUMO

Catalytic Conversion of Toluene by Biochar Modified with Kmno4

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SSRN 2022年

作者： Jin, Xiaoling Zhang, Kai Jiang, Jiahao Zhu, Zhengrong 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 Kunming Institute of Physics Kunming650223 China

This study aims to investigate the effects of biomass species, modification treatment, experimental time and atmosphere on the catalytic conversion of toluene (model tar compound) by the biochar from gasification of oak, wheat straw and Enteromorpha. The gas and liquid phase products are detected by GC and GC-MS, respectively. The physical and chemical characteristics of biochar samples are analyzed by SEM-EDS, XRD and XPS. The results show that the activity of oak char modified by KMnO 4 (Mn-OC) is higher than that of other biochar samples. The KMnO 4 modification improves the pore structure, increases oxygen-containing groups and enhances the activity of biochar. The relatively high toluene conversion rate (53.96%) and low carbon deposition rate (3.41%) of Mn-OC indicates that KMnO 4 is more suitable for the modification of oak char. H 2 and aromatic hydrocarbons (especially biphenyl and their derivatives) are the main components of gas and liquid products, respectively. The proportion of H 2 in the total volume of H 2 , CO, CH 4 and CO 2 of Mn-OC reaches 56.94%. The addition of water vapor is helpful to the formation of oxygen-containing groups, more uniform distribution of inorganic salt particles and the improvement of biochar surface structure. Thus, adding moderate water vapor is beneficial to promote the catalytic activity of biochar. The toluene conversion rate and the total volume fraction of four main gases decrease with the increase of experimental time. They reduce significantly when the experimental time is longer than 120 min, from 44.51% (120 min) to 24.86% (180 min), which might be due to the damage of pore structure and the consumption of oxygen-containing functional groups. © 2022, The Authors. All rights reserved.

关键词： Toluene