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Experimental study on pressure and temperature distributions for low mass flux steam jet in subcooled water

Science China(Technological Sciences) 2009年第6期52卷 1493-1501页

作者： JunJie Yan XinZhuang Wu DaoTong Chong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

A low mass flux steam jet in subcooled water was experimentally *** transition of flow pattern from stable jet to condensation oscillation was observed at relatively high water *** axial total pressures,the axial and radial temperature distributions were measured in the jet *** results indicated that the pressure and temperature distributions were mainly influenced by the water *** correlations corrected with water temperature were given to predict the dimen-sionless axial pressure peak distance and axial temperature distributions in the jet region,the results showed a good agreement between the predictions and ***,the self-similarity property of the radial temperature was obtained,which agreed well with Gauss *** present work,all the dimensionless properties were mainly dependent on the water temperature but weakly on the nozzle size under a certain steam mass flux.

关键词： dimensionless self-similarity steam jet condensation temperature distribution total pressure

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Analysis of flow instabilities in forced-convection steam generator

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Nuclear Science and Techniques 2006年第3期17卷 185-192页

作者： WU Ge-Ping QIU Sui-Zheng SU Guang-Hui JIA Dou-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇ an 710049 China

Because of the practical importance of two-phase instabilities, substantial efforts have been made to date to understand the physical phenomena governing such instabilities and to develop computational tools to model the dynamics. The purpose of this study is to present a numerical model for the analysis of flow-induced instabilities in forced-convection steam generator. The model is based on the assumption of homogeneous two-phase flow and ther- modynamic equilibrium of the phases. The thermal capacity of the heater wall has been included in the analysis. The model is used to analyze the flow instabilities in the steam generator and to study the effects of system pressure, mass flux, inlet temperature and inlet/outlet restriction, gap size, the ratio of do / di, and the ratio of qi / qo on the system be- havior.

关键词：蒸汽发生器强迫对流流动不稳定性双相不稳定性

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An investigation of flow characteristics and critical heat flux in vertical upward round tube

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Nuclear Science and Techniques 2006年第3期17卷 170-176页

作者： FAN Pu QIU Sui-Zheng JIA Dou-Nan State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China

Prediction of critical heat flux (CHF) in annular flow is important for the safety of once - through steam generator and the reactor core under accident conditions. The dryout in annular flow occurs at the point where the film is depleted due to entrainment, deposition, and evaporation. The film thickness, film mass flow rate along axial distribution, and CHF are calculated in vertical upward round tube on the basis of a separated flow model of annular flow. The theoretical CHF values are higher than those derived from experimental data, with error being within 30%.

关键词：环流临界热通量沉积挟带核反应堆工程

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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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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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Performance of CO_2 absorption in a diameter-varying spray tower

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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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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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Hydrogen production performance optimization for direct-coupled photovoltaic electrolysis systems based on a novel 3D opto-electro-thermal model

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Applied Energy 2025年 392卷

作者： Wang, Hao Wang, Weiding Lin, Chuanjie Lai, Yongquan Li, Changchen Xu, Ziyou Yang, Yuanbo Yang, Yimin Dong, Wenxuan Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi'an Jiaotong University Xi'an710049 China

Photovoltaic-powered electrolysis systems represent a promising approach for large-scale renewable energy storage, with direct-coupled systems offering particular advantages in terms of reduced system complexity and cost. However, a mismatch issue between photovoltaic (PV) and electrolysis (EC) modules of these systems could be caused by suboptimal structural design and flow rate control strategies, leading to a significant reduction in hydrogen production performance. While these problems could potentially be addressed through numerical simulation, existing low-dimension models are overly simplified due to the assumptions of spatial homogeneity, failing to adequately capture the intricate coupling mechanisms among optical, thermal, electrical and gas-liquid flow phenomena in these complex systems. In this study, a novel 3D opto-electro-thermal model has been developed for direct-coupled systems, utilizing semiconductor drift-diffusion equations and a gas-liquid two-phase flow model within each grid cell. This advanced model facilitates comprehensive performance assessments during the optimization of the fundamental system structure (PV-EC), including the evaluation of novel system configurations that integrate photovoltaic/thermal (PV/T) and contact-based thermal designs. Additionally, it could help to streamline flow rate control by optimizing the relative sizing between the membrane electrode assembly (MEA) of EC and PV modules. The results demonstrate that the PV/T-EC Non-thermal integration structure achieves the maximum Solar-to-Hydrogen efficiency (STH). Moreover, by setting the relative sizing at 2.25 %, maintaining the flow rate in a wide range without precise control could be sufficient to achieve outstanding and stable STH under real-world fluctuating conditions. This allows the flow rate control strategy to be effectively streamlined. The findings could provide guidance for optimizing hydrogen production performance by refining system structure and flow

关键词： Model structures

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