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16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015

作者： Wang, Kai Cai, Rong Ren, Wuyue Qiu, Suizheng Tian, Wenxi Su, G.H. Chen, Ronghua School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao Tong University Xianning West Rd. 28 Xi'an Shaanxi710049 China

ISBN: (纸本)9781510811843

ECC safety injection nozzles are usually placed at the primary circulation pipelines as for the Gen II-plus nuclear reactor. Small Break Loss of Coolant Accident (SBLOCA) may lead to Pressurized Thermal Shock (PTS) on the Reactor Pressure Vessel (RPV) wall. Based on the Emergency Core Cooling (ECC) of a 2nd generation plus PWR, the CFD software CFX was adopted to simulate the thermal mixing phenomenon of the sub-cooled water from safety injection nozzle and high temperature water or steam from the cold leg which later forms into stratified flow. Also the steam-water simulation takes the steam condensation into consideration and steam condensation is characterized by a relatively large interfacial area between the two phases. For simulations of single-phase thermal mixing, the temperature profiles of different points were obtained and agreed well with the experiment. For steam mixing with water, the gas volume profile and the condensation rate of the steam were obtained and compared with the experiment, and the effect of different injection nozzle water velocities were also studied.

关键词： Steam

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Boiling heat transfer and bubble distribution on inhomogeneous wetting surface patterned with Sierpinski carpet

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APPLIED THERMAL engineering 2020年 180卷 115818-115818页

作者： Yu, Ting Cui, Chenyi Qi, Baojin Wei, Jinjia Yuan, Jia Qaisrani, Mumtaz A. Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China Xian Jiaotong Univ Suzhou Acad Suzhou 215123 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

During the chips working, heat is mainly generated from its central area and shows a typical inhomogeneous distribution. To meet the chip's cooling requirements, a novel Sierpinski hydrophobic/hydrophilic fractal pattern (SHFP) was designed and fabricated on copper surface in the present study. This fractal pattern can match with the real heat flux distribution and the bubble sizes distribution, fully utilizing the enhancement potential of hydrophobic spots, so it can well avoid the disadvantage of a sharp reduction in the CHF. The dynamic behavior of the bubbles on this SHFP surface was studied theoretically and experimentally. The results show that small bubbles nucleated, grew and merged with neighboring bubbles at the preset high-order hydrophobic spots and their distribution presents typical fractal characteristics. Then small bubbles started moving from the high-order hydrophobic region to central low-order region spontaneously and a large bubble was finally formed and departed rapidly in the central first-order hydrophobic region after bubbles coalesced. Through observation and analysis, we found that the nucleation sites of the bubbles and their movement and merging can be designed and planned in advance on the well-designed SHFP surface, so the distribution of the bubbles can precisely match the actual distribution of heat flux. The comparison shows that the well-designed SHFP surface presented a low wall superheat at ONB and the heat transfer coefficient was even better than the mono-hydrophobic surface after the secondary pool boiling enhancement. The critical heat flux also reached the same level (i.e., about 95%) of natural spatial distribution, which is greatly superior to the surface with regular hydrophobic spots. Therefore, the SHFP surface designed in this study is a very suitable surface for utilizing the distribution of hydrophobic spots to enhance boiling heat transfer.

关键词： Inhomogeneous wetting Fractal pattern Sierpinski carpet Bubble distribution Heat transfer enhancement Pool boiling

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A kinetics and dynamics study on the auto-ignition of dimethyl ether at low temperatures and low pressures 38th

A kinetics and dynamics study on the auto-ignition of dimeth...

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38th International Symposium on Combustion, 2021

作者： Huang, Wenlin Zhao, Qian Huang, Zuohua Curran, Henry J. Zhang, Yingjia State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Combustion Chemistry Centre School of Chemistry Ryan Institute MaREI Nui Galway Ireland

Dimethyl ether (DME)/air mixtures at various equivalence ratios from lean (0.5) to extremely rich (5.0) were ignited behind reflected shock waves at a fixed pressure (3.0 atm) over the temperature range 625 K– 1200 K. The ignition behavior was different from that at high-pressures, with a repeatable ignition delay time fall-off feature observed experimentally in the temperature transition zone from the negative temperature coefficient (NTC) regime to the high-temperature regime. The fall-off behavior showed strong equivalence ratio dependence and disappeared completely at an equivalence ratio of 5.0. A local ignition kernel postulate was implemented numerically to quantifiably examine the inhomogeneous premature ignition. At low temperature, no pre-ignition occurs in the mixture. A conspicuous discrepancy was observed between the measurements and constrained UV simulations at temperatures beyond the NTC regime. A third O₂ addition reaction sub-set was incorporated into AramcoMech 3.0, together with related species thermochemistry calculated using the G3/G4/CBS-APNO compound method, to explore the low-temperature deviation. The new reaction class did not influence the model predictions in IDT, but the updated thermochemistry does. Sensitivity analyses indicated that the decomposition of hydroperoxy-methylformate plays a critical role in improving the low-temperature oxidation mechanism of DME.

关键词： Ethers

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Molten Ag₂SO₄-based Ion-Exchange Preparation of Ag_0.5La_0.5TiO₃ for Photocatalytic O₂ Evolution

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CHEMISTRY-AN ASIAN JOURNAL 2017年第8期12卷 882-889页

作者： Zong, Shichao Cheng, Cheng Shi, Jinwen Huang, Zhenxiong Hu, Yuchao Yang, Honghui Guo, Liejin Xi An Jiao Tong Univ IRCRE State Key Lab Multiphase Flow Power Engn MFPE 28 West Xianning Rd Xian 710049 Peoples R China Xi An Jiao Tong Univ Dept Environm Sci & Engn 28 West Xianning Rd Xian 710049 Peoples R China

Ag0.5La0.5TiO3 with an ABO(3) perovskite structure was synthesized by a newly developed ion-exchange method. Molten Ag2SO4 instead of traditional molten AgNO3 was used as Ag+ source in view of its high decomposition temperature (1052 degrees C), thereby guaranteeing the complete substitution of Ag+ for Na+ in Na0.5La0.5TiO3 with a stable ABO(3) perovskite structure at a high ion-exchange temperature (700 degrees C). Under full-arc irradiation, the O-2-evolution activity of Ag0.5La0.5TiO3 was about 1.6 times that of Na0.5La0.5TiO3 due to the optimized electronic band structures and local lattice structures. On the one hand, the substitution of Ag+ for Na+ elevated the VBM and thus narrowed the band gap from 3.19 to 2.83eV, thereby extending the light-response range and, accordingly, enhancing the photoexcitation to generate more charge carriers. On the other hand, the substitution of Ag+ for Na+ induced a lattice distortion of the ABO(3) perovskite structure, thereby promoting the separation and migration of charge carriers. Moreover, under visible-light irradiation, Ag0.5La0.5TiO3 displayed notable O-2 evolution whereas Na0.5La0.5TiO3 showed little O-2 evolution, thus demonstrating that the substitution of Ag+ for Na+ enabled the use of visible light to evolve O-2 photocatalytically. This work presents an effective route to explore novel Ag-based photocatalysts.

关键词： ion exchange oxygen evolution perovskite photocatalysis silver

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Bacterial Cellulose Composite Solid Polymer Electrolyte With High Tensile Strength and Lithium Dendrite Inhibition for Long Life Battery

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Energy & Environmental Materials 2021年第3期4卷 434-443页

作者： Yuhan Li Zongjie Sun Dongyu Liu Shiyao Lu Fei Li Guoxin Gao Min Zhu Mingtao Li Yanfeng Zhang Huaitian Bu Zhiyu Jia Shujiang Ding Department of Applied Chemistry School of ChemistryXi’an Key Laboratory of Sustainable Energy Materials ChemistryMOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterState Key Laboratory of Electrical Insulation and Power EquipmentXi’an Jiaotong UniversityXi’an 710049China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Department of Materials and Nanotechnology SINTEF IndustryForskningsveien 1Oslo 0373Norway School of Chemistry and Chemical Engineering MOE Key Laboratory of Cluster ScienceBeijing Institute of TechnologyBeijing 100081China

The development of metallic lithium anode is restrained by lithium dendrite growth during *** solid polymer electrolyte with high mechanical strength and lithium ion conductivity could be applied to inhibit lithium dendrite *** prepare the high-performance solid polymer electrolyte,the environment-friendly and cheap bacterial cellulose(BC)is used as filler incorporating with PEO-based electrolyte owing to good mechanical properties and Li salts ***/Li TFSI/BC composite solid polymer electrolytes(CSPE)are prepared easily by aqueous mixing in *** lithium ion transference number of PEO/Li TFSI/BC CSPE is 0.57,which is higher than PEO/Li TFSI solid polymer electrolyte(SPE)(0.409).The PEO/Li TFSI/BC CSPE exhibits larger tensile strength(4.43 MPa)than PEO/Li TFSI SPE(1.34 MPa).The electrochemical window of composite electrolyte is widened 1.43 V by adding *** functional theory calculations indicate that flex of PEO chains around Li atoms is suppressed,suggesting the enhanced lithium ion *** molecular orbitals results suggest that an unfavorable intermolecular charge transfer lead to achieve higher potential for BC composite *** solid-state Li metal battery with PEO/Li TFSI/BC CSPE delivers longer cycle life for 600 cycles than PEO/Li TFSI SPE battery(50 cycles).Li symmetrical battery using PEO/Li TFSI/BC CSPE could be stable for 1160 h.

关键词： all solid-state battery bacterial cellulose composite polymer electrolyte DFT calculations HOMO and LUMO

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Improvement in hydrogen desorption performances of magnesium based metal hydride reactor by incorporating helical coil heat exchanger

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2016年第36期41卷 16108-16121页

作者： Wu, Zhen Yang, Fusheng Zhu, Luying Feng, Penghui Zhang, Zaoxiao Wang, Yuqi Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Northwest Univ Sch Chem Engn Xian 710069 Peoples R China

Mg-based metal hydride has been viewed as one of the most promising materials for hydrogen storage. However, large amount of reaction heat during the hydrogen absorption/desorption cycles negatively affects the heat and mass transfer, thus leading to poor performances. In this work, helical coil heat exchanger (HCHE) is proposed to be inserted into Mg-based metal hydride reactor for improving the heat and mass transfer. The models on pressure-composition-temperature properties and hydrogen desorption kinetics of Mg-based reactor are firstly established for the simulation through experiments. The comparison of hydrogen desorption performances for the reactors incorporating the conventional straight tube, finned tube and new helical coil heat exchangers is conducted based on numerical simulation. The comparison results show that the HCHE has the best effects on improving the heat and mass transfer characteristics of reactor among the three heat exchangers, due to its secondary circulation. Besides, it is suggested that the influence of hydrogen pressure gradient should be considered for the prediction of the performance of Mg-based metal hydride reactor with HCHE. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Magnesium based metal hydride reactor Heat and mass transfer Helical coil heat exchanger Hydrogen desorption

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Theoretical analysis on bubble radius and pressure fluctuation during steam bubble condensation

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PROGRESS IN NUCLEAR ENERGY 2021年 142卷 1页

作者： Qiu, Binbin Yang, Qingchuan Chen, Weixiong Liu, Jiping Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

The pressure oscillation and condensation behavior of steam bubbles at low steam mass flux are experimentally and theoretically studied in this work. Based on the synchronous measurement system of bubble behavior and pressure oscillation, it is found that the steam bubble condenses first and then expands and contracts, the water pressure reaches the maximum (about 13 kPa) when the bubble condenses to the minimum radius (about 1 mm). Subsequently, taking into account the movement of the bubble and the change of internal pressure during the bubble condensation process, a theoretical model of heat and mass transfer in the bubble condensation process is established, which shows that the steam bubble collapse is caused by heat transfer and the bubble internal pressure fluctuation. In the early condensation process of steam bubble, the bubble internal pressure continues to increase, meanwhile, the influence of bubble internal pressure on bubble condensation continues to increase. During the later expansion and contraction process of the bubble, the bubble internal pressure decreases first and then increases, the bubble behavior is mainly controlled by the bubble internal pressure.

关键词： Steam bubble condensation Pressure oscillation Bubble internal pressure Bubble behavior

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A comparison of low-pressure premixed laminar flames of 1,3-butadiene and 1,3-butadiene/acetylene with synchrotron radiation 7

A comparison of low-pressure premixed laminar flames of 1,3-...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Wei, L.X. Wu, X.S. Chen, Z.Y. Huang, Z.H. Yuan, T. Li, Y.Y. Tian, Z.Y. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei230029 China

Low-pressure premixed laminar flames of 1,3-butadiene/oxygen /argon and 1,3-butadiene+acetylene/oxygen/argon have been investigated with tunable synchrotron photoionization and molecular beam mass spectrometry. Flame species, including not only isomeric intermediates, but also those with same molecular weight while different formulae, are identified by measuring the ionization energies. Mole fraction profiles of the main species are derived from the measured signal intensities at different flame positions. Comparison between the two flames reveals that the existence of excessive acetylene in 1,3-butadiene flame can not lead to an obvious increase of aromatics formation under the condition investigated. © 2009 Combustion Institute. All rights reserved.

关键词： Acetylene

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A Combined Experimental and Computational Study on the Shuttle Mechanism of Piperazine for the Enhanced CO2 Absorption in Aqueous Piperazine Blends

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2022年第3期61卷 1301-1312页

作者： Luo, Qinlan Zhou, Qulan Feng, Bin Li, Na Liu, Shicheng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Hunan Univ Hunan Prov Key Lab Cost Effect Utilizat Fossil Fu Joint Int Ctr CO Capture & Storage iCCS Coll Chem & Chem Engn Changsha 410082 Peoples R China Xian Thermal Power Res Inst Co Ltd Xian 710054 Peoples R China

Piperazine (PZ) blends containing PZ and monoethanolamine (MEA)/N-methyldiethanolamine (MDEA)/2-amino-2-methyl-propanol (AMP) were experimentally and computationally investigated to analyze their potential capabilities for CO2 capture, and the shuttle mechanism of PZ for enhanced CO2 absorption were verified. In experiments, the concentration of both PZ and MEA/MDEA/AMP were varied to show the effect of concentration ratio and the influence of amine components on the CO2 absorption rate and capacity. Experimental results showed that all the PZ blends possessed high absorption rates and large absorption capacities. To further understand the interaction behavior of amines/products and possible reaction pathways, both qualitative and quantitative C-13 NMR analyses were conducted. The results indicated the conversion between absorption products, which can release free PZ to capture CO2 and consequently improve the absorption performance. Moreover, the static quantum mechanical calculations and ab initio molecular dynamics (AIMD) simulations combined with metadynamics sampling were conducted to evaluate the thermodynamic stability of absorption products and kinetically favorable key elementary reactions in PZ blends. This study highlights an accurate description of the shuttle effect of PZ for the enhanced CO2 capture by PZ blends.

关键词： Chemical reactions Organic compounds Reaction mechanisms Amines Absorption

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A Study of Moist Air Condensation Characteristics in a Transonic flow System

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ENERGIES 2021年第13期14卷 4052页

作者： Wang, Jie Gu, Hongfang Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

When water vapor in moist air reaches supersaturation in a transonic flow system, non-equilibrium condensation forms a large number of droplets which may adversely affect the operation of some thermal-hydraulic equipment. For a better understanding of this non-equilibrium condensing phenomenon, a numerical model is applied to analyze moist air condensation in a transonic flow system by using the theory of nucleation and droplet growth. The Benson model is adopted to correct the liquid-plane surface tension equation for realistic results. The results show that the distributions of pressure, temperature and Mach number in moist air are significantly different from those in dry air. The dry air model exaggerates the Mach number by 19% and reduces both the pressure and the temperature by 34% at the nozzle exit as compared with the moist air model. At a Laval nozzle, for example, the nucleation rate, droplet number and condensation rate increase significantly with increasing relative humidity. The results also reveal the fact that the number of condensate droplets increases rapidly when moist air reaches 60% relative humidity. These findings provide a fundamental approach to account for the effect of condensate droplet formation on moist gas in a transonic flow system.

关键词： moist air non-equilibrium condensation relative humidity transonic flow Laval nozzle

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