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6th International Conference on Fluid Mechanics and Industrial Applications, FMIA 2022

作者： Dong, Wu-Han Gao, Ming Shen, Zhong-Xiang Zhang, Li-Xin Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

Based on dynamic microlayer evaporation model. Heat transfer mechanism of nuclear boiling and microlayer thickness under single bubble on heated surface. It has a lot to do with the temperature of the wall. Therefore, this paper studies the mechanism of bubble microlayer and makes comparative analysis with its experiments. It is helpful to master nuclear boiling heat transfer more comprehensively. In the study of individual bubble microlayer thickness. The effects of time and radius on wall temperature are considered in this paper. The theoretical formula of initial thickness of microlayer is deduced. The theoretical formula is compared with the experimental data of microlayer evaporation under the nucleation bubble. It was found that the experimental data fell within ±25% of the formula range. It is consistent with the previous experimental research. © Published under licence by IOP Publishing Ltd.

关键词： Evaporation

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Rotor dynamic analysis of supercritical carbon dioxide Bryton cycle coaxial integrated unit 14

Rotor dynamic analysis of supercritical carbon dioxide Bryto...

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14th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Hangzhou 2023

作者： Xu, Xiaokang Yang, Yi Wang, Jiangfeng Lou, Juwei Chen, Liangqi 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

ISBN: (纸本)9798350301359

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 CO2 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 CO2 coaxial integrated unit. © 2023 IEEE.

关键词： critical speed unbalance response vibration analysis

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Preferential Formation of Ethylene via Electrocatalytic CO_(2) Reduction on Mesoporous Cu_(2)O Nanoparticles:Synergistic Effects of Pore Structure Confinement and Surface Amine

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Chinese Journal of Chemistry 2024年第16期42卷 1846-1852页

作者： Haifeng Zhang Dun Li Zhifang Chen Yingying Wang Haoyu Sun Feng Liu Maochang Liu Yiqun Zheng Hongwen Huang School of Chemistry Chemical Engineering and MaterialsJining UniversityQufuShandong 273155China College of Materials Science and Engineering Hunan UniversityChangshaHunan 410082China Health Management Department Shandong Vocational College of Light IndustryZiboShandong 255300China International Research Center for Renewable Energy National Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiotong UniversityXi'anShaanxi 710049China

We present a facile synthetic strategy to create mesoporous Cu_(2)O nanocrystals with tunable pore structures and surface functional groups of amine derivatives for efficient and preferable electrochemical conversion of CO_(2) into *** structural characteristics of theseCu_(2)O nanocrystals can be manipulated using a set of amine derivatives,such as pyridine,4,4'-bipyridine,and hexamethylenetetramine,during the oxidative etching process of Cu nanocrystals by bubbling gaseous oxygen in N,N-dimethylformamide *** amine derivatives not only serve as surface functional groups but also significantly affect the resulting pore *** synergistic effect of pore structure confinement and surface amine functionalization leads to the superb Faradaic efficiency(FE)of 51.9% for C_(2)H_(4),respectively,together with the C_(2)H_(4) partial current density of -209.4 mA·cm^(-2) at -0.8 V *** hydrogen electrode(RHE).The relatively high selectivity towards C_(2)H_(4) was investigated using DFT simulations,where 4,4'-bipyridine functionalized Cu_(2)O seemed to favor the C_(2)H_(4) formation with the low free energy of the *** study provides a feasible strategy to manipulate the pore structure and surface functionalization of mesoporous Cu_(2)O nanocrystals by regulating the oxidative etching process,which sheds light on the rational preparation of high-performance CO_(2)RR electrocatalysts.

关键词： Amines Ethylene Cuprous oxide CO_(2)reduction Mesoporous materials

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engineering practice and economic analysis of ozone oxidation wet denitrification technology

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Chinese Journal of Chemical engineering 2021年第1期34卷 401-408页

作者： Yang Li Defu Che Chenglong Yang Mingyu Yao Tingwen Zhao Kangli Fu Hanchen Zhao Xi’an Thermal Power Research Institute Co LtdXi’an 710032China State Key Laboratory of Multiphase Flow for Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

SO_(2)and NO emitted from coal-fired power plants have caused serious air pollution in *** this study,a test system for NO oxidation using O_(3)is *** basic characteristics of NO oxidation and products forms are studied.A separate test system for the combined removal of SO_(2)and NO_(x)is also established,and the absorption characteristics of NO_(x)are *** characteristics of NO oxidation and NO_(x)absorption were verified in a 35 t·h^(-1)industrial boiler wet combined desulfurization and denitrification *** operating economy of ozone oxidation wet denitrification technology is *** results show that O_(3)has a high rate and strong selectivity for NO *** O_(3)is insufficient,the primary oxidation product is NO_(2).When O_(3)is present in excess,NO_(2)continues to get oxidized to N_(2)O_(5)or NO_(3).The removal efficiency of NO_(2)in alkaline absorption system is low(only about 15%).NOx removal efficiency can be improved by oxidizing NO_(x)to N_(2)O_(5)or NO_(3)by increasing ozone *** the molar ratio of O_(3)/NO is 1.77,the NOx removal efficiency reaches 90.3%,while the operating cost of removing NO_(x)per kilogram is 6.06 USD(NO_(2)).

关键词： Ozone Denitrification Wet process engineering practice

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Comparative experimental study on dynamic characteristics of bubble microlayers in small channel flow boiling and pool boiling 6

Comparative experimental study on dynamic characteristics of...

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6th International Conference on Fluid Mechanics and Industrial Applications, FMIA 2022

作者： Shen, Zhongxiang Gao, Ming Dong, Wuhan Zhang, Lixin Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

The microlayer present at the bottom of the bubble plays a very important role in heat transfer during nucleation boiling. In this paper, the dynamic characteristics of microlayer at the bottom of boiling bubble in a small channel were studied by laser interferometry method and high speed camera, and the results were compared with pool boiling experiments. The results show that the bubbles have an obvious tendency to slip in the flow boiling. The microlayer interference fringe is deformed and no longer a complete Newtonian ring. By analyzing the thickness distribution of microlayer in different directions in flow boiling and the change of micro-contact angle in the flow direction, it was found that the micro-contact angle in the flow direction became larger with the growth of bubbles. © Published under licence by IOP Publishing Ltd.

关键词： Contact angle

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Research on the THMC Coupling Model for Enhanced Geothermal Systems Based on the Framework of EDFM 29th

Research on the THMC Coupling Model for Enhanced Geothermal ...

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29th International Conference on Computational and Experimental engineering and Sciences, ICCES 2023

作者： Zhang, Weitao Han, Dongxu Jiao, Kaituo Chen, Yujie Yuan, Qing Gong, Liang Yu, Bo Qingdao266580 China Beijing Key Laboratory of Pipeline Critical Technology and Equipment for Deepwater Oil and Gas Development School of Mechanical Engineering Beijing Institute of Petrochemical Technology Beijing102617 China State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9783031429866

The Enhanced Geothermal System (EGS) involves a complex thermo-hydro-mechanical-chemical (THMC) coupling process during long-term heat extraction. However, many models used to solve fractured reservoir problems are computationally time-consuming, especially when dealing with reservoir-scale engineering problems. To address this challenge, this paper proposes a novel THMC coupling model that solves the governing equations using a unified FVM framework based on the embedded discrete fracture model (EDFM). The accuracy of the model is confirmed by comparing the THC coupling and displacement (M) results with the Fully Resolved Solution Method (FRSM) from MRST software and COMSOL, respectively. Moreover, the model developed is utilized to simulate and analyze the spatiotemporal behavior of pressure, temperature, concentration, and mechanical deformation in EGS. The results suggest that the model is appropriate for effectively assessing the long-term production performance of EGS. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Finite volume method

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Numerical study of specific C-shaped heat exchanger using porous medium and coarse mesh coupling method

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International Journal of Thermal Sciences 2025年 210卷

作者： He, Shaopeng Wang, Shiqi Wang, Mingjun Tian, W.X. Qiu, S.Z. Su, G.H. State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

Porous medium method is an effective simplified approach for the heat exchanger simulation when the numerous tubes and complex structures bring unacceptable computational resources to full-scale simulation. However, for the specific C-shaped heat exchanger, the tube side resistance and flow distribution characteristics that significantly affects the heat transfer and natural circulation performance cannot be obtained by the traditional porous medium method coupled with the one-dimensional node model for tube side. It is urgent to develop a new coupling method that can not only simplify modeling and calculation, but also obtain tube side high-resolution flow heat transfer characteristics. This study presents a novel calculation method which couples the porous medium mesh and the tube side coarse mesh. The coupling method was then applied to a typical C-shaped passive residual heat removal heat exchanger (PRHR HX), which is significant to the stable operation and the mitigation of accident conditions in the nuclear power plant. The coupling calculation method was validated against the full-scaled simulation and data from scaled-down experiment. The average relative error of heat transfer power is 2.1 % under steady state conditions. Under transient conditions, the average absolute error of the fluid temperature and wall temperature are less than 6 K. Then the 3D thermal-hydraulic characteristics of PRHR HX was studied. Owing to a greater gravitational pressure head, the mass flow rates in the extended tubes surpass those in the shorter tubes by a relative deviation of 27.4 %. The upper horizontal tube's heat exchange capacity constitutes approximately 70 % of the total power, leading to enhanced natural circulation. The outlet temperatures from various tubes tend to equalize. The boiling area gradually extended down along the heat transfer tubes. Our work would present an innovative calculation method to the numerical study and design optimization of the C-shaped heat

关键词： Nuclear power plants

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Comparative analysis on gas–solid drag models in MFIX-DEM simulations of bubbling fluidized bed

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Chinese Journal of Chemical engineering 2023年第12期64卷 64-75页

作者： Ruiyu Li Xiaole Huang Yuhao Wu Lingxiao Dong Srdjan Beloševic Aleksandar Milicevic Ivan Tomanovic Lei Deng Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and ResearchFoshan 528300China Department of Thermal Engineering and Energy "VINCA" Institute of Nuclear Sciences–National Institute of the Republic of SerbiaUniversity of BelgradeMike Petrovica Alasa 12-1411351 VincaPO Box 52211001 BelgradeSerbia

In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)*** influence of superficial gas velocity on gas–solid flow is also *** results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS *** the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly *** time domain and frequency domain analysis results of pressure drop of each drag model are *** is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM *** the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.

关键词： MFIX-DEM Simulation Dense flow Gas-solid Bubbling fluidized bed Drag model

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Improvement on Numerical Simulation of Supercritical Water flow in Horizontal Tubes: A Buoyancy-Tuned Turbulence Prandtl Number Model

SSRN

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SSRN 2024年

作者： Hou, Zhenghui Guo, Xinyang Liang, Zhicheng Yang, Kuang Yang, Chaofan Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

To improve the predictive accuracy of numerical simulations for supercritical water, the effect of turbulence Prandtl number (Prt) on supercritical water heat transfer was extensively studied using the Shear-Stress Transport (SST) k-ω turbulence model. The efficacy of typical turbulence Prandtl number models for predicting heat transfer in horizontal tubes with supercritical water was evaluated based on wall temperatures measured experimentally and fluid temperatures obtained from multi-point temperature measurement devices. These models successfully demonstrated the phenomenon of thermal stratification due to physical property variations, but their predictive performance near the pseudocritical temperature, particularly in the top wall region, was not satisfying. Building upon this, a new turbulence Prandtl number model suitable for horizontal supercritical water tubes, named the SWBT model, was developed through constant calibration and the addition of buoyancy tuned. This model effectively replicates severe heat transfer deterioration (HTD) and buoyancy-induced improvements in heat transfer, showing robust predictive capabilities with a wide array of experimental data from both the authors and other researchers. The model was tested across ranges of P=24.5-26.5 MPa, q/G=0.11-0.67, and tube diameters of 7.5 mm, 26 mm and 43 mm. Additionally, the model's performance was benchmarked against experimental results of axially non-uniform heat flux conducted by the authors, successfully reproducing the variations in wall temperature due to changes in heat flux. This study substantially enhances the accuracy of numerical simulations for supercritical water in horizontal tubes, offering valuable insights for the engineering applications of supercritical water and the design of heat exchangers. © 2024, The Authors. All rights reserved.

关键词： Prandtl number

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Effect of Fuel System on the Heat Releasing Method and flow-Path Design of Rocket-Based Combined Cycle Engine 14

Effect of Fuel System on the Heat Releasing Method and Flow-...

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14th International Conference on Mechanical and Aerospace engineering, ICMAE 2023

作者： Liu, Xiao Wang, Yinhu Yang, Yiyan Shi, Lei Yan, Dekun Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an China Beijing Institute of Long March Vehicle Beijing China Northwestern Polytechnical University Science and Technology on Combustion Internal Flow and Thermal-structure Laboratory Xi'an China

ISBN: (纸本)9798350340327

Multi-components rocket-based combined cycle (RBCC) engine is widely applied in most two-stage-To-orbit program due to stable operation performance under variable flight conditions. Present researches numerically compared RBCC's performance under ramjet mode and scramjet mode, respectively, by using two fuel system, hydrogen and kerosene together with a \mathrm{k}-\omega SST turbulence model. Researches showed that the combustor area ratio should be increased to keep stable pressure difference balance between inflow and flame because of higher caloric value using hydrogen. Distributed heat addition method is benifit for overall performance improvement when using hydrogen. Different from using kerosene, head should be delayedly added in combustor downtream under scramjet mode. Moreover, the advanced heat addition amount should be decreased under ramjet mode to ensure effective isolator operation. © 2023 IEEE.

关键词： Hydrogen

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