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Numerical investigation and analysis of heat transfer enhancement in channel by longitudinal vortex based on field synergy principle

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中国高等学校学术文摘·能源与动力工程 2008年第1期2卷 71-78页

作者： Wenquan TAO Junmei WU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Environment and Chemical Engineering Xi'an Polytechnic University Xi'an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

3-D numerical simulations were presented for laminar flow and heat transfer characteristics in a rectangular channel with vortex generators. The effects of Reynolds number (from 800 to 3 000), the attack angle of vortex generator (from 15° to 90°) and the shape of vortex generator were examined. The numerical results were analyzed based on the field synergy principle. It is found that the inherent mechanism of the heat transfer enhancement by longitudinal vortex can be explained by the field synergy principle, that is, the second flow generated by vortex generators results in the reduction of the intersection angle between the velocity and fluid temperature gradient. The longitudinal vortex improves the field synergy of the large downstream region of longitudinal vortex generator (LVG) and the region near (LVG); however, transverse vortex only improves the syn-ergy of the region near vortex generator. Thus, longitudinal vortex can enhance the integral heat transfer of the flow field, while transverse vortex can only enhance the local heat transfer. The synergy angle decreases with the increase of Reynolds number for the channel with LVG to differ from the result obtained from the plain channel, and the triangle winglet performs better than the rectanglar one under the same surface area condition.

关键词： longitudinal vortex heat transfer enhancement field synergy principle

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Uncertainty and sensitivity analysis of in-vessel phenomena under severe accident mitigation strategy based on ISAA-SAUP program

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Nuclear Science and Techniques 2024年第1期35卷 108-123页

作者： Hao Yang Ji-Shen Li Zhi-Ran Zhang Bin Zhang Jian-Qiang Shan School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The phenomenology involved in severe accidents in nuclear reactors is highly ***,integrated analysis programs used for severe accident analysis heavily rely on custom empirical parameters,which introduce considerable ***,in recent years,the field of severe accidents has shifted its focus toward applying uncertainty analysis methods to quantify uncertainty in safety assessment programs,known as“best estimate plus uncertainty(BEPU).”This approach aids in enhancing our comprehension of these programs and their further development and *** study concentrates on a third-generation pressurized water reactor equipped with advanced active and passive mitigation *** an Integrated Severe Accident Analysis Program(ISAA),numerical modeling and uncertainty analysis were conducted on severe accidents resulting from large break loss of coolant *** uncertainty parameters of the ISAA program were meticulously *** Wilks'formula,the developed uncertainty program code,SAUP,was employed to carry out Latin hypercube sampling,while ISAA was employed to execute batch *** analysis was then conducted on two figures of merit,namely hydrogen generation and the release of fission products within the pressure *** calculations revealed that hydrogen production and the fraction of fission product released exhibited a normal distribution,ranging from 182.784 to 330.664 kg and from 15.6 to 84.3%,*** ratio of hydrogen production to reactor thermal power fell within the range of 0.0578–0.105.A sensitivity analysis was performed for uncertain input parameters,revealing significant correlations between the failure temperature of the cladding oxide layer,maximum melt flow rate,size of the particulate debris,and porosity of the debris with both hydrogen generation and the release of fission products.

关键词： Gen-III PWR Severe accident mitigation Wilks’formula Hydrogen Fission products Uncertainty and sensitivity analysis

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Void fraction measurement and calculation model of vertical upward co-current air-water slug flow

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Chinese Journal of Chemical engineering 2022年第11期51卷 178-198页

作者： Teng Wang Miao Gui Jinle Zhao Qincheng Bi Tao Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Nuclear Science and Technology Xi’an Jiaotong UniversityXi’an 710049China

The focus of this paper is on the measurement and calculation model of void fraction for the vertical upward co-current air-water slug flow in a circular tube of 15 mm inner diameter. High-speed photography and optical probes were utilized, with water superficial velocity ranging from 0.089 to 0.65 m·s^(-1)and gas superficial velocity ranging from 0.049 to 0.65 m·s^(-1). A new void fraction model based on the local parameters was proposed, disposing the slug flow as a combination of Taylor bubbles and liquid slugs. In the Taylor bubble region, correction factors of liquid film thickness Cδand nose shape CZ*were proposed to calculate aTB. In the liquid slug region, the radial void fraction distribution profiles were obtained to calculate aLS, by employing the image processing technique based on supervised machine learning. Results showed that the void fraction proportion in Taylor bubbles occupied crucial contribution to the overall void fraction. Multiple types of void fraction predictive correlations were assessed using the present data. The performance of the Schmidt model was optimal, while some models for slug flow performed not outstanding. Additionally, a predictive correlation was correlated between the central local void fraction and the cross-sectional averaged void fraction, as a straightforward form of the void fraction calculation model. The predictive correlation showed a good agreement with the present experimental data, as well as the data of Olerni et al., indicating that the new model was effective and applicable under the slug flow conditions.

关键词： Slug flow Gas-liquid flow Void fraction Measurement Optical probe Model

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Confining Phosphoric Acid in Quaternized COF Channels for Ultra-Stable and Fast Anhydrous Proton Transport

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Angewandte Chemie - International Edition 2025年第13期64卷 e202423458页

作者： Pang, Xiao Shi, Benbing Liu, Yawei Wu, Hong Shen, Jianliang Guan, Jingyuan Wang, Xiaoyao Fan, Chunyang Cao, Li Zhu, Tianhao Kong, Yan Jiang, Zhongyi Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical Engineering and Technology Tianjin University Tianjin300072 China Ningbo Key Laboratory of Green Petrochemical Carbon Emission Reduction Technology and Equipment Zhejiang Institute of Tianjin University Zhejiang Ningbo315201 China Joint School of National University of Singapore and Tianjin University International Campus of Tianjin University Binhai New City Fuzhou350207 China Haihe Laboratory of Sustainable Chemical Transformations Tianjin300192 China Chinese Acad Sci Beijing Key Lab Ion Liquids Clean Proc CAS Key Lab Green Proc & Engn State Key Lab Multiphase Complex Syst Inst Proc En Beijing100190 China

Phosphoric acid (H3PO4) doping is a widely employed strategy to facilitate anhydrous proton transport in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). However, significant H3PO4 leaching during long-term operation poses critical challenges to maintaining membrane stability and proton conductivity. Herein, H3PO4 is incorporated into positively charged nanochannels of quaternized covalent organic framework membranes (QACOFMs), leveraging strong electrostatic interactions and confinement effects to achieve exceptional H3PO4 retention under hydration conditions. Moreover, the shortened hydrogen bond length between H3PO4 (O−H…O 3PO4@QACOFMs facilitate ultra-fast anhydrous proton transport. As a result, the H3PO4@QACOFMs exhibit superior anhydrous proton transport in a broader temperature range (60 °C–200 °C) and the highest proton conductivity reaches about 379.7 mS cm−1 at 200 °C. © 2025 Wiley-VCH GmbH.

关键词： Hydrogen bonds

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Comments on Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD

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Applied Mathematics and Mechanics(English Edition) 2009年第5期30卷 669-676页

作者：张红娜宇波王艺魏进家李凤臣 Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum School of Energy Science and Engineering Harbin Institute of Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

The explicit compact difference scheme, proposed in Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD by Lin et al., published in Applied Mathematics and Mechanics （English Edition）, 2007, 28（7）, 943-953, has the same performance as the conventional finite difference schemes. It is just another expression of the conventional finite difference schemes. The proposed expression does not have the advantages of a compact difference scheme. Nonetheless, we can more easily obtain and implement compared with the conventional expression in which the coefficients can only be obtained by solving equations, especially for higher accurate schemes.

关键词： explicit compact difference scheme conventional finite difference scheme central difference scheme upwind difference scheme

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First law-based thermodynamic analysis on Kalina cycle

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 145-151页

作者： Ying ZHANG Maogang HE Zhen JIA Xun LIU State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Based on the first law of thermodynamics,and adopting the Peng-Robinson equation (P-R equation) as the basic equation for the properties of ammonia-water mixtures,a thermodynamic analysis on a single-stage distillation Kalina cycle is presented.A program to calculate the thermodynamic properties of ammoniawater mixtures,and that for calculating the performance of Kalina cycles,were developed,with which the heatwork conversion particulars of Kalina cycles were theoretically *** influences on the cycle performance of key parameters,such as the pressure and temperature at the inlet of the turbine,the back pressure of the turbine,the concentration of the working solution,the concentration of the basic solution and the cycle multiplication ratio,were analyzed.

关键词： engineering thermophysics Kalina cycle ammonia-water mixtures P-R equation thermodynamic property

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Numerical simulation of flow characteristics for a labyrinth passage in a pressure valve

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Journal of Hydrodynamics 2016年第4期28卷 629-636页

作者：王海民赵越汪建兴孔祥帅刘欢李科良王喜芳 School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology

A tortuous labyrinth passage consists of a series of right angle turns in a disk of high pressure control *** this paper,numerical simulations are made for the velocity and pressure distributions in this *** is shown that the “series passage” can induce a pressure dropping more *** main function of the “series passage” is to induce a pressure dropping while the “parallel passage” is mainly to regulate the *** a cross sectional area process,a series of reduction and expansion,the pressure will also see dropping and partial recovery,which is called the multistage pressure *** this way,the velocity can be controlled in a reasonable level anywhere in this tortuous labyrinth *** the fluid pressure dropping in a downwards serrated way,the pressure is higher than the local saturate vapor pressure,therefore,no cavitation is induced by the phase transition.

关键词： passage valve dropping multistage turns sectional anywhere regulate vortex inlet

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Study on Liutex-driven reward for intelligent flow control by dynamic feature-based deep reinforcement learning

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AIP Advances 2025年第5期15卷

作者： Wang, Qi Dong, Xiangrui You, Sunyu Cai, Xiaoshu School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai200093 China

The issue of flow separation over an airfoil under weak turbulent conditions is addressed and resolved through the deep reinforcement learning (DRL) strategy. To suppress the generation of separation flow and the instability of the vortex shedding alley over an airfoil, a novel reward function named RLiutex, considering the suppression of the rigid rotation intensity and core size of the vortex, is first proposed in this paper. The great potential of this Liutex-driven reward for effective large eddy elimination and aerodynamic optimization is verified in this work. Furthermore, a dynamic feature-based DRL (DF-DRL) framework is redeveloped to markedly enhance the learning efficiency and convergence speed. The combination of the Liutex-driven reward function with the DF-DRL framework results in an exceptional aerodynamic performance, with minimal fluctuations in both drag and lift coefficients, highlighting the potential of this approach for advanced flow control strategies. © 2025 Author(s).

关键词： Deep reinforcement learning

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Synergistic effect of oxygen species and vacancy for enhanced electrochemical CO_(2) conversion to formate on indium oxide

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eScience 2024年第3期4卷 134-141页

作者： Tengfei Ma Zihao Jiao Haoran Qiu Feng Wang Ya Liu Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Indium-based oxides are promising electrocatalysts for producing formate via CO_(2) reduction reaction,in which*OCHO is considered the key ***,we identified that the*COOH pathway could be preferential to produce formate on In_(2)O_(3)of In/In_(2)O_(3) heterojunction due to the synergistic effect of oxygen species and ***,*CO_(2) and *COOH were observed on In_(2)O_(3) and related to formate production by in situ Raman *** theoretical calculations further demonstrated that the energy barrier of the*COOH formation on In_(2)O_(3) was decreased in the presence of oxygen vacancy,similar to or lower than that of the*OCHO formation on the In *** a result,a formate selectivity of over 90%was obtained on prepared In/In_(2)O_(3) heterojunction with 343±7mAcm^(-2) partial current ***,when using a Si-based photovoltaic as an energy supplier,10.11%solar-to-fuel energy efficiency was achieved.

关键词： Electrocatalytic CO_(2)reduction Formate In_(2)O_(3) Oxygen species Oxygen vacancy

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Effect of ignition timing and hydrogen fraction on combustion and emission characteristics of natural gas direct-injection engine

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 194-201页

作者： Jinhua WANG Zuohua HUANG Bing LIU Ke ZENG Jinrong YU Deming JIANG State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

An experimental study on the combustion and emission characteristics of a direct-injection spark-ignited engine fueled with natural gas/hydrogen blends under various ignition timings was *** results show that ignition timing has a significant influence on engine performance,combustion and *** interval between the end of fuel injection and ignition timing is a very important parameter for direct-injection natural gas *** turbulent flow in the combustion chamber generated by the fuel jet remains high and relative strong mixture stratification is introduced when decreasing the angle interval between the end of fuel injection and ignition timing giving fast burning rates and high thermal *** maximum cylinder gas pressure,maximum mean gas temperature,maximum rate of pressure rise and maximum heat release rate increase with the advancing of ignition ***,these parameters do not vary much with hydrogen addition under specific ignition timing indicating that a small hydrogen fraction addition of less than 20% in the present experiment has little influence on combustion parameters under specific ignition *** exhaust HC emission decreases while the exhaust CO2 concentration increases with the advancing of ignition *** the lean combustion condition,the exhaust CO does not vary much with ignition *** the same ignition timing,the exhaust HC decreases with hydrogen addition while the exhaust CO and CO2 do not vary much with hydrogen *** exhaust NOx increases with the advancing of' ignition timing and the behavior tends to be more obvious at large ignition advance *** brake mean effective pressure and the effective thermal efficiency of natural gas/hydrogen mixture combustion increase compared with those of natural gas combustion when the hydrogen fraction is over 10%.

关键词： natural gas hydrogen ignition timing combustion emissions direct-injection

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