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Performance of CO_2 absorption in a diameter-varying spray tower

Chinese Journal of Chemical engineering 2017年第8期25卷 1109-1114页

作者： Xiaomei Wu Yunsong Yu Zhen Qin Zaoxiao Zhang School of Chemical Engineering and Technology Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

The application of spray towers for CO2 capture is a development trend in recent years. However, most of the previous jobs were conducted in a cylindrical tower by using a single spray nozzle, whose configuration and performance is not good enough for industrial application. To solve this problem, the present work proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the heat and mass transfer of CO2 absorption process. Experiments were performed to investigate the mass transfer performance （in terms of the CO2 removal rate （η） and the overall mass transfer coefficient （KGae）） of the improved spray tower under various operating conditions. Experimental results showed that the liquid to gas ratio and mole ratio of MEA to C02 are major factors, which affect the absorption performance and the maximums of η and KGae that are 94.0% and 0.574 kmol. m^-3·h^-1·kPa^-1, respectively, under the experimental conditions. Furthermore, new correlations to predict the mass transfer coefficient of the proposed spray tower are developed in various CO2 concentrations with a Pearson Correlation Coefficient over 90%.

关键词： Carbon dioxide Absorption Diameter-varying spray tower Mass transfer

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NUMERICAL SIMULATION OF WET STEAM CONDENSING flow WITH AN EULERIAN/EULERIAN MODEL

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Chinese Journal of Mechanical engineering 2003年第2期16卷 156-159页

作者： Li LiangFeng ZhenpingLi Guojunstate key laboratory of multiphase flowin Power engineering,Xi’ an Jiaotong University,XI’ an 710049, China Xi' an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an 710049

Wet steam condensing flow in low-pressure steam turbine leads to efficiencylosses and blade erosions. In order to investigate this problem by numerical approach, anEulerian/Eulerian model has been developed, in which the wet steam is regarded as mixture comprisingtwo coupled systems: the vapor phase and the liquid phase. These two systems are both described byconservation equations. High resolution TVD scheme is employed to capture condensing phenomena inwet steam flow. This model has been validated by numerical simulations of condensing flows in 1D and2D nozzles. Compared with experimental data, a good agreement is observed. This Eulerian/Eulerianmodel can be extended to 3D calculation of condensing flow.

关键词： wet steam condensing flow numerical simulation eulerian/eulerian model

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Construction of Z-Scheme In_(2)S_(3)-TiO_(2) for CO_(2) Reduction under Concentrated Natural Sunlight

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Chinese Journal of Structural Chemistry 2022年第1期41卷 34-39页

作者： Ya Liu Fangbo Yu Feng Wang Shengjie Bai Guiwei He State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Producing chemical fuels from sunlight enables a sustainable way for energy *** various solar fuel generation approaches,photocatalytic CO_(2) reduction has the advantages of simple structure,mild reaction condition,directly reducing carbon emissions,***,most of the current photocatalytic systems can only absorb the UV-visible spectrum of solar ***,finding a way to utilize infrared light in the photocatalytic system has attracted more and more ***,a Z-scheme In_(2)S_(3)-TiO_(2) was constructed for CO_(2) reduction under concentrated natural *** infrared light was used to create a high-temperature environment for photocatalytic *** evolution rates of H2,CO,and C2H5OH reached 262.2,73.9,and 27.56μmol・h^(-1)・g^(-1),respectively,with an overall solar to fuels efficiency of 0.002%.This work provides a composite photocatalyst towards the utilization of full solar light spectrum,and could promote the research on photocatalytic CO_(2) reduction.

关键词： solar energy CO_(2) In_(2)S_(3) TiO_(2)

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Verification and validation plus uncertainty quantification of heat transfer simulation for liquid metal in wire-wrapped rod assembly

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International Communications in Heat and Mass Transfer 2025年 165卷

作者： Liu, Zhenglong Zhong, Peiling Qiu, Hanrui Wang, Mingjun Tian, Wenxi Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

A complete CFD best practice process is proposed, including Phenomena Identification and Ranking Table (PIRT), Verification and Validation (V&V), and Uncertainty Quantification (UQ). The heat transfer of liquid metal within a rod assembly under both normal and blocked conditions is used as an example to demonstrate the full CFD process. key flow and heat transfer phenomena are identified, and model sensitivity analyses are performed based on these phenomena. Turbulent Prandtl models, porous blockage models and different meshing strategies sensitivity analysis are conducted. Uncertainty quantification is performed. The discretization uncertainty is calculated using the Grid Convergence Index (GCI). The convergence orders are greater than unity for all cases except the fluid temperature in the blocked condition using meshing strategy 2. The input parameter uncertainty is estimated using finite difference. The model uncertainty is derived. Under normal condition, the model uncertainty of the wall and fluid temperatures are 2.88 K and 3.37 K, respectively. Under blocked condition, the model uncertainty of wall temperature is slightly higher than fluid temperature. The wall temperature uncertainty for strategies 1 and 2 are 8.46 K and 9.03 K, while the fluid uncertainty of strategy 1 and 2 are 3.57 K and 3.06 K, respectively. © 2025 Elsevier Ltd

关键词： Liquid metals

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Simulation of flow across complicated domain between tube bundles by the discrete vortex method

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自然科学进展(英文版) 2003年第3期13卷 213-218页

作者： CHEN Bin Guo Liejin Yang Xiaogang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an J iaotong University Xi'an 710049 China

On the basis of the analysis of numerical simulation methods for the complicated domain between tube bundles, an improved Lagragian discrete vortex method (DVM) and corresponding algorithm are put forward to solve the practical difficulties of flow across tube bundles. With this method the amount of vortices can be reduced considerably, which makes quick calculation possible. Applied to the practical configuration of horizontal tube bundles, the DVM simulation is carried out and compared with the experimental results. Both the transient flow field and the profile of mean velocity and fluctuations are in good agreement with experimental results, which indicate that the DVM is suitable for the simulation of single-phase flow across tube bundles.

关键词： tube bundles discrete vortex method numerical simulation

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Morphology Structure Evolution and Combustion Reactivity of Bituminous Char at Around Ash Melting Temperature

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Journal of Thermal Science 2022年第6期31卷 2189-2202页

作者： ZHANG Yandi YANG Huan WANG Bo HMShahzaib KHAN DUAN Xiaoli LIU Yinhe State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi'an Jiaotong UniversityXi'an 710049China

In slag tapping furnaces, char particles undergo a series of complex structural evolution before and after being captured by the liquid slag layer. The evolution results affect the carbon conversion rate and are affected by temperature fluctuations, especially in the ash melting temperature zone. Experimental study on structure evolution of bituminous char prepared at around ash melting temperature was carried out on a fixed bed. The morphology, specific surface area and mineral chemical composition were measured at different temperatures. Experimental results show that the number density and the size of ash droplets exuded on the char surface increased significantly with the increasing temperature. The ash specific surface area from gasification was slightly greater than that from combustion. The residual content of chloride in the char become 1% and the contents of Fe, K, Mg and Na decrease significantly during the pyrolysis process across the ash melting temperature zone. The diffraction intensity of oldhamite increase which indicates the reaction of carbon substrate with minerals during the evolution;the diffraction intensity of quartz dramatically decreases for the reason of anorthite generation. The ignition and burnout temperatures of char were found to increase and the combustion stability decreased with the increasing pyrolysis temperature.

关键词： coal char structure evolution carbothermal reaction combustion

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Wall-to-bed heat transfer in supercritical water fluidized bed using CFD-DEM

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Particuology 2021年第3期19卷 113-123页

作者： Tianning Zhang Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi’an Jiaotong UniversityXi’anShaanxi 710049PR China

Supercritical water fluidized bed(SCWFB)reactors are designed to gasify biomass or coal with high *** this paper,the wall-to-bed heat transfer characteristics in SCWFB are studied using the computational fluid dynamics and discrete element method(CFD-DEM)coupled with a constant heat flux *** different methods are considered to deal with the multiphase heat flux boundary in CFD-DEM because there is currently no single widely accepted ***’s method predicts a more accurate wall-to-bed heat transfer coefficient in SCWFB than Lattanzi’s method according to comparisons of the simulation results with an empirical *** influences of temperature,pressure,velocity,and the solid phase properties,such as the particle diameter,particle heat capacity,particle thermal conductivity,and particle density,on the SCWFB wall-to-bed heat transfer characteristics are studied based on Zhang’s *** simulation results help reveal the SCWFB heat transfer characteristics.

关键词： Supercritical water Fluidized bed Heat transfer DEM-CFD Constant heat flux

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Stall-induced aeroelastic instability of floating offshore wind turbines: Comparison of frequency domain and time domain quasi-steady approaches

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Renewable Energy 2025年 251卷

作者： Meng, Qingshen Yu, Wei Wu, Faming Hua, Xugang Chen, Chao State Key Laboratory of Bridge Engineering Safety and Resilience College of Civil Engineering Hunan University Changsha410006 China Flow Physics and Technology Faculty of Aerospace Engineering Delft University of Technology HS Delft2629 Netherlands Wind Power Business Division CRRC Zhuzhou Institute Co.Ltd Zhuzhou412000 China

With the increasing size of floating offshore wind turbines (FOWTs), stall-induced aeroelastic instability has become a critical issue. This study numerically investigates this instability for FOWTs at stand-still conditions using time and frequency domain approaches. A nonlinear aeroelastic model based on quasi-steady theory and a linearized version are used for time and frequency domain simulations, respectively. Hydrodynamic damping considers both radiation and viscous drag effects. The aeroelastic instability of a stand-still NREL OC3-Hywind 5MW FOWT is analyzed for various inflow yaw misalignment angles. Frequency domain simulation shows rotor edgewise and tower side-side modes exhibit stall-induced instability due to aerodynamic negative damping at specific yaw misalignment and azimuth angles. The platform's yaw mode also shows small negative damping, despite large hydrodynamic damping, while other platform modes remain dynamically stable. Safety margins of FOWTs are analyzed for multi-mode stability, and an active control strategy is proposed to prevent stall-induced instability in all unstable modes. Limit cycle oscillations in the rotor's in-out plane are observed from time domain simulation. Instability regions predicted by both analyses highly overlap, but frequency domain results are more conservative. Blade instability may cause high-frequency vibrations in platform movements with limited amplitudes and severe oscillations in tower structures. © 2025 Elsevier Ltd

关键词： Wind turbines

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Curvature-property coupling governed heat transfer deterioration in supercritical helically coiled tubes: Mechanistic insights and mitigation strategies via structural parametrization

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International Journal of Thermal Sciences 2025年 215卷

作者： Chang, Fucheng Xin, Jiaxing Wu, Xiaoyi Li, Liwei Li, Huixiong Zhu, Yanlin National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China China Special Equipment Testing and Research Institute Beijing100029 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd Shanghai200233 China

The unique thermo-hydrodynamic coupling phenomena in the helically coiled tube (HCT) handling supercritical fluids present both opportunities and challenges for next-generation compact heat exchangers. While the pronounced thermophysical property variations near pseudo-critical temperatures (Tpc) and curvature-induced secondary flows synergistically enhance heat transfer coefficient (HTC), their nonlinear coupling mechanisms may unexpectedly provoke severe heat transfer deterioration (HTD). Through systematic numerical investigations, this study reveals that circumferential wall temperature inhomogeneity (CWTI) exhibits an inverted N-shaped evolution, providing valuable insights for thermal homogenization design near Tpc. The secondary flow Reynolds number (Se), quantifying secondary flow intensity, shows a monotonic increase with decreasing coil diameter (Dc) or inner diameter (Di), reaching saturation in high-enthalpy regions. Notably, CWTI demonstrates non-monotonic behavior, achieving minimum values near Tpc before manifesting distinct rebound characteristics near Tpc conditions. Parametric analysis establishes that: (1) Elevating heat flux (q) increases Se, reducing Dc boosts it by 50.3 %, and decreasing Di raises it by 60.0 %. (2) HTD predominantly initiates at the outer wall under high-q conditions, with Dc reduction achieving HTD suppression and 26.9 % enhancement in the local HTC;(3) Reducing the Di results in a reduction of maximum CWTI by 22.5 %–28.6 %, suggesting that structural parametrization effectively mitigates wall temperature non-uniformity, thus suppressing the HTD. While centered on supercritical water, the dimensionless scaling relationships demonstrate extendibility to other media, with the curvature-property coupling mechanism both elucidating fundamental interactions and guiding robust heat exchanger design. © 2025 Elsevier Masson SAS

关键词： Electric heating

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Operational efficiency improvement in a water supply network: Machine learning-enhanced leakage identification and water resource conservation

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Journal of Water Process engineering 2025年 75卷

作者： Liu, Hongbo Zhang, Junbo An, Wenhui Chen, Yang Yuan, Xiang Zhang, Guosheng Lichtfouse, Eric Ma, Jiale Huang, Jin Tu, Yiqian School of Environment and Architecture University of Shanghai for Science and Technology 516 Jungong Road Shanghai 200093 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China Shanghai Urban Construction Design and Research Institute (Group) Co. Ltd. Shanghai 200125 China

Pipeline ruptures in water supply networks can induce significant water loss and may pose risks of water quality deterioration, including potential contamination by pathogens and pollutants. This issue can be addressed by predicting the location of leakage points in the pipeline network and controlling the leakage. Here we designed a hydraulic model for leakage localization using a genetic algorithm-backpropagation neural network, to predict the leakage points in the water supply system of an exposition area consuming 117,211 m³ of water per day in Eastern China. Then, using the model results, pressure-regulating valves were installed in areas with lower network safety. Results show that the error in predicting the leakage points localization ranged from 14.48 m to 121.69 m. The installation of pressure-regulating valves, reduced the average water pressure from 33.54 m to 32.64 m (2.7 %) and, in turn, decreased the simulated background leakage by 9684 m³ of water per day. Compared to traditional acoustic-based methods, the proposed machine learning approach enables more accurate leak localization by leveraging pressure variation features. © 2025 Elsevier Ltd

关键词： Pipeline leakage Point leakage model Pressure monitoring Pressure regulating valve Supply water

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