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Two-phase flow instabilities in helical tubes of once-through steam generators

PROGRESS IN NATURAL SCIENCE 1997年第3期7卷 360-365页

作者： Zhou, FD Shi, SP Hu, MS State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Helical tube is one type of once-through stream generators in integrative nuclear device. The thermal-hydrodynamic instabilities in helical tubes of a once-through steam generator (HTOTSG) with exit-steam superheated were studied by using multi-variable liner-frequency-domain theory. Based on the drift-flux model, a small perturbation method, as well as Laplace transformation theory, was empolyed to linearize the system of partial differential equations. A computer code called HTOTSGM-D was developed to investigate the influences of inlet flow rate, inlet subcooling, heat flux, and system pressure on oscillations. The calculated results showed that the above factors must be considered comprehensively in once-through steam generator design and operation, even though the installation of the entrance throttles was still an effective way to stabilize the system.

关键词： two-phase flow instabilities helical tube once-through stream generator

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Prediction of Heat Transfer Rates for Shell-and-Tube Heat Exchangers by Artificial Neural Networks Approach

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Journal of Thermal Science 2006年第3期15卷 257-262页

作者： Qiuwang WANG Gongnan XIE Ming ZENG Laiqin LUO State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Shaanxi Xi＇an710049 China

This work used artificial neural network(ANN)to predict the heat transfer rates of shell-and-tube heatexchangers with segmental baffles or continuous helical baffles,based on limited experimental *** BackPropagation (BP) algorithm was used in training the *** network configurations were *** deviation between the predicted results and experimental data was less than 2%.Comparison withcorrelation for prediction shows ANN *** is recommended that ANN can be easily used to predict theperformances of thermal systems in engineering applications,especially to model heat exchangers for heattransfer analysis.

关键词： heat transfer rate Artificial Neural Network shell-and-tube heat exchanger back propagation

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Effect of the Density Difference on Fluid Distribution in Layered Rock Samples

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Energy & Fuels 2025年第9期39卷 4412-4420页

作者： Yongfei Yang Tonghui Liu Yingwen Li Weichen Sun Hai Sun Lei Zhang Junjie Zhong Kai Zhang Jun Yao State Key Laboratory of Deep Oil and Gas China University of Petroleum (East China) Qingdao 266580 P. R. China；Research Center of Multiphase Flow in Porous Media School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 P. R. China Geosteering & Logging Research Institute Sinopec Matrix Corporation Qingdao 266071 P. R. China Research Center of Multiphase Flow in Porous Media School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 P. R. China

During geological CO2storage, gravity segregation due to fluid density differences significantly affects the efficiency and safety of the process. This can result in premature CO2breakthrough, reduced storage efficiency, and increased leakage risks. This study aims to investigate how gas migrates in layered heterogeneous reservoirs over time due to prolonged density differences and to assess the resulting impact on fluid distribution. We use artificially layered heterogeneous sandstone cores for experimentation. After completing gas injection and water flooding experiments, the core was positioned with the low permeability layer (LPL) at the top and the high permeability layer (HPL) at the bottom for an extended period. Because the effects of density differences are not easily discernible during gas–water two-phase flow under typical driving forces, we applied micro-CT imaging technology to visualize and analyze how density differences influence gas flow within the core. The results demonstrate that during the static placement period following displacement, gas clusters exhibit different flow behaviors at the pore throats. Most gas clusters struggle to overcome the Jamin effect and enter into the upper pores; a few large-volume gas clusters, driven by density differences, partially pass through the throats into the upper pores, while the remaining portions are stranded within the throats, leading to a snap-off phenomenon; while some gas clusters successfully overcome the Jamin effect and enter the upper pores in significant numbers. The experimental findings indicate that the LPL effectively hinder the upward migration of the nonwetting phase gases from bottom and fluid density differences significantly influence gas–water distribution changes. This study provides critical insights for optimizing CO2storage and offers a new perspective on fluid behavior in layered heterogeneous reservoirs.

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Theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor

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Nuclear Science and Techniques 2006年第5期17卷 314-320页

作者： GOU Jun-Li 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

This article presents a theoretical investigation on the steady-state natural circulation characteristics of a new type of pressurized water reactor. Through numerically solving the one-dimensional steady-state single-phase conservative equations for the primary circuit and the steady-state two-phase drift-flux conservative equations for the secondary side of the steam generator, the natural circulation characteristics were studied. On the basis of the pre- liminary calculation analysis, it was found that natural circulation mass flow rate was proportional to the exponential function of the power and that the value of the exponent is related to the operating conditions of the secondary side of the steam generator. The higher the outlet pressure of the secondary side of the steam generator, the higher the pri- mary natural circulation mass flow rate. The larger height difference between the core center and the steam generator center is favorable for the heat removal capacity of the natural circulation.

关键词：核反应堆压水堆稳态自然循环高度差理论研究

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Recovery of waste heat in cement plants for the capture of CO2

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Frontiers of Chemical Science and engineering 2012年第1期6卷 104-111页

作者： Ruifeng DONG Zaoxiao ZHANG Hongfang LU Yunsong YU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Large amounts of energy are consumed during the manufacturing of cement especially during the calcination process which also emits large amounts of CO2. A large part of the energy used in the making of cement is released as waste heat. A process to capture CO2 by integrating the recovery and utilization of waste heat has been designed. Aspen Plus software was used to calculate the amount of waste heat and the efficiency of energy utilization. The data used in this study was based on a dry process cement plant with a 5-stage preheater and a precalciner with a cement output of 1 Mt/y. According to the calculations： 1） the generating capacity of the waste heat recovery system is 4.9MW. 2） The overall CO2 removal rate was as high as 78.5%. 3） The efficiency of energy utilization increased after the cement producing process was retrofitted with this integrated design.

关键词： cement industry waste heat recovery utiliza-tion CO2 removal

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Stability of stratified flow and slugging in horizontal gas-liquid flow

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Progress in Natural Science:Materials International 2005年第11期15卷 1026-1034页

作者： GU Hanyang and GUO Liejin (state key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China) State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an 710049 China

A transient one-dimensional two-fluid model is proposed to investigate numerically the interfacial instability and the onset of slugging for liquid-gas flow in a horizontal duct. In the present model, the effects of surface tension and transverse variations in dynamic pressure are taken into account. The evolution of interfacial disturbances is displayed and compared with the linear viscous Kelvin-Helmholtz stability analyses. It shows that interfacial wave is more instable due to the non-linear effect. The model predicts well the stability limit of stratified flow in comparison with the experimental data, and also automatically tracks the onset of slugging. The results show that the initiation of hydrodynamic slugging is related to local interfacial instability. Based on the cycle of slugging, a model for slug frequency is presented, which predicts the trends of slug frequencies with gas/liquid flow rate well in comparison with the available data. The effects of physical properties on slugging have been examined. It is found that with the increase in the gas viscosity and liquid density the slugging would be inhibited, whereas, with the increase in liquid viscosity and gas density, the slugging can be promoted.

关键词： two-fluid model Kelvin-Helmholtz stability interfacial instability onset of slugging gas-liquid stratified flow.

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Online recognition of the multiphase flow regime

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Science China(Technological Sciences) 2008年第8期51卷 1186-1194页

作者： BAI BoFeng ZHANG ShaoJun ZHAO Liang ZHANG XiMin GUO LieJin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The key reasons that the present method cannot be used to solve the industrial multi- phase flow pattern recognition are clarified firstly. The prerequisite to realize the online recognition is proposed and recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.

关键词： multiphase flow flow regime online recognition multi-sensor data fusion

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Experimental Investigation on Hydrophobic Behavior of Carbon Spheres Coated Surface Made from Microplastics

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Journal of Renewable Materials 2021年第12期9卷 2159-2174页

作者： Peng Liu Bin Bai Cui Wang Yunan Chen Zhiwei Ge Wenwen Wei Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China

In this paper,a simple method to plate a hydrophobic coating on the inner surface of a small-scaled tube was proposed,where the coating consisted of carbon *** common plastics polystyrene,polycarbonate and polyethylene were used as the feedstocks to be processed in supercritical water in a quartz tubular *** reaction,the contact angle of droplet on the inner surface of the quartz tube was turned out to be over 100°,significantly larger than that of the blank tube 54°.When processing polystyrene in the 750℃ supercritical water for 10 min,the largest contact angle was obtained,up to 145°.Besides,in this sample,the size of carbon spheres was smallest,about 2.09μm diameter on *** comparing among different types of plastics under the same condition,the contact angle of surface made from PC took the dominant position over that of PS and PE,124°,100°and 90°,*** the sample made from PC,carbon spheres adhered into a mountainlike shape,producing a binary geometric ***,this research could be helpful in the discussion of plastic waste management and carbon spheres fabrication with low cost.

关键词： Plastic wastes hydrothermal method carbon spheres supercritical water hydrophobicity

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Single electron loss in the collisions of C^(3+) and atomic hydrogen

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Chinese Physics B 2010年第9期19卷 344-348页

作者：刘会平欧阳晓平胡华四苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi'anjiaotong University

This paper studies the projectile electron loss cross sections of C^3＋ colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities （25 keV/u-600 keV/u）. The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.

关键词： single electron loss over-barrier model

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A mathematical model and numerical simulation of pressure wave in horizontal gas-liquid bubbly flow

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自然科学进展（英文版） 2004年第4期14卷 344-349页

作者： HUANG Fei BAI Bofeng Guo Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

By using an ensemble-averaged two-fluid model,with valid closure conditions of interfacial momentum exchange due to virtual mass force,viscous shear stress and drag force,a model for pressure wave propagation in a horizontal gas-liquid bubbly flow is *** to the small perturbation theory and solvable condition of one-order linear uniform equations,a dispersion equation of pressure wave is *** pressure wave speed calculated from the model is compared and in good agreement with existing *** to the dispersion equation,the propagation and attenuation of pressure wave are investigated *** factors affecting pressure wave,such as void fraction,pressure,wall shear stress,perturbation frequency,virtual mass force and drag force,are *** result shows that the decrease in system pressure,the increase in void fraction and the existence of wall shear stress,will cause a decrease in pressure wave speed and an increase in the attenuation coefficient in the horizontal gas-liquid bubbly *** effects of perturbation frequency,virtual mass and drag force on pressure wave in the horizontal gas-liquid bubbly flow at low perturbation frequency are different from that at high perturbation frequency.

关键词： pressure wave two-fluid model gas-liquid bubbly flow dispersion speed attenuation

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