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Towards uniform distributions of reactants via the aligned electrode design for vanadium redox flow batteries

APPLIED ENERGY 2020年第0期259卷 114198-000页

作者： Sun, J. Jiang, H. R. Zhang, B. W. Chao, C. Y. H. Zhao, T. S. Hong Kong Univ Sci & Technol Dept Mech & Aerosp Engn Kowloon Clear Water Bay Hong Kong Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Hong Kong Dept Mech Engn Pokfulam Rd Hong Kong Peoples R China

Enhancing the hydraulic permeability of electrodes along both the through-plane and in-plane directions is essential in flow-field structured vanadium redox flow batteries, as it can promote uniform distributions of reactants, lower the concentration overpotential, and therefore improve battery performances. In this work, uniaxially-aligned carbon fiber electrodes with the fiber diameter ranging from 7 to 12 mu m (average similar to 10 mu m) are fabricated by electrospinning method. Attributed to the enhanced permeability of the aligned structure, the battery assembled with the prepared electrodes exhibits an energy efficiency of 84.4% at a current density of 100 mA cm(-2), which is 13.2% higher than that with conventional electrospun fiber electrodes. The permeability in the in-plane direction is further tailored by adjusting the orientation of aligned fibers against the flow channels. Results show that when the orientation of aligned fibers is perpendicular to the direction of flow channels, the battery delivers the largest discharge capacity and the highest limiting current density (similar to 900 mA cm(-2)). Such an enhancement in the battery performance can be ascribed to the more uniform in-plane distribution of reactants and current by maximizing the permeability along the direction vertical to the flow channels, as evidenced by a three-dimensional model.

关键词： Aligned fiber Uniform distribution Concentration polarization Electrospinning Vanadium redox flow battery

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Effect of water addition on auto-ignition of kerosene under afterburner relevant conditions 12

Effect of water addition on auto-ignition of kerosene under ...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Sun, Wuchuan Huang, Wenlin Qin, Xiaokang Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Ignition delay times were measured for stoichiometric kerosene/air mixtures with and without H2O addition behind reflected shock conditions: pressures of 0.45 - 7.5 atm and temperatures of 900 - 1450 K. The effect of H2O addition on the reactivity of RP-3 was explored at various pressure and temperatures. The Arrhenius-type expressions were fitted by using the current ignition data. A four-component surrogate model of RP-3 was proposed based on similarity criterion of function group. The proposed model generally reproduces the tendency of pressure-dependence of ignition delay times but it over-predicts the experimental data at lower pressures. The addition of H2O presents different effects at elevated pressures. The kinetic analysis was performed to clarify the kinetic and thermodynamic effects. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Kerosene

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Application of a Magnetic Field in Saturated Film Boiling of a Magnetic Nanofluid (MNF) under Reduced Gravity

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ENERGIES 2021年第3期14卷 634-634页

作者： Guo, Kaikai Chang, Fucheng Li, Huixiong Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China China Aerodynam Res & Dev Ctr Facil Design & Instrumentat Inst Mianyang 621000 Sichuan Peoples R China China Aerodynam Res & Dev Ctr State Key Lab Aerodynam Mianyang 621000 Sichuan Peoples R China

To overcome the problem of abnormally large bubbles and the large reduction of heat flux under low gravity, the computational model of magnetic nanofluid (MNF) boiling flow was used to systematically study the thermodynamic characteristics of an MNF-saturated film boiling with and without the magnetic field. This study found that in the absence of a magnetic field, the decrease of the gravity level makes the bubble size increase and the bubble departure time increase, and the lower the gravity level, the worse the boiling heat transfer. However, after applying the magnetic field, bubble size decreases significantly and the bubble departure time is shortened. As the magnetic field intensity increases, the difference in bubble size and heat transfer characteristics between different gravity levels becomes smaller and smaller, which shows that for the boiling flow of MNF under low gravity levels, applying a magnetic field can effectively avoid the appearance of abnormally large bubbles, enhance heat transfer, and improve the safety of related heat transfer equipment.

关键词： magnetic nanofluid (MNF) reduced gravity film boiling enhanced heat transfer

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Effects of Flue Gas Recirculation on Combustion and Heat Flux Distribution in 660 Mw Double-Reheat Tower-Type Boiler

SSRN

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SSRN 2022年

作者： Deng, Lei Dong, Lingxiao Bai, Yang Wu, Yuhao Liu, Hu Belošević, Srdjan Tomanović, Ivan Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Guoshen Institute of Technology CHN ENERGY Xi'An710065 China Department of Thermal Engineering and Energy "VINČA" Institute of Nuclear Sciences National Institute of thе Republic of Serbia University of Belgrade Mike Petrovića Alasa 12-14 11351 Vinča PO Box 522 Belgrade11001 Serbia

The ultra-supercritical double-reheat boiler has attracted more attention because of high parameters, low pollution and large capacity. However, there are some difficulties in the development of this technology, such as adjusting the reheat steam temperature. In this study, computational fluid dynamics simulation is used to analyze a 660 MW double-reheat tower-type pulverized coal-fired boiler. The influence of flue gas recirculation (FGR) on heat transfer characteristics and combustion process in the furnace (including heating surfaces in the upper parts of the furnace) are evaluated. The user-defined function approach predicates CO reduction effect on NO x . The results show that the flow at the horizontal section through the centerline of recirculating flus gas nozzles is rotating. The velocity distribution changes into an elliptical rotating flow when FGR ratio is 20%. At higher FGR ratios, the high-temperature area (1565-1700 K) shrinks and both the NO x concentration at the low-temperature superheater outlet and oxygen concentration in the furnace descend. Oxygen concentration at low-temperature superheater outlet first increases and then decreases. In the main combustion zone, the heat flux peak of water-cooled wall is about 330 kW m -2 . As FGR ratio increases from 0% to 20%, the rate of water-cooled wall heat absorption to total boiler decreases by 3.50%. This rate for reheater and superheater increases by 2.53% and 2.13%, respectively. © 2022, The Authors. All rights reserved.

关键词： Temperature

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Stable CdTe Photoanodes with Energetics Matching Those of a Coating Intermediate Band

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ACS ENERGY LETTERS 2020年第6期5卷 1865-1871页

作者： Chen, Xiangyan Shen, Xin Shen, Shaohua Reese, Matthew O. Hu, Shu Yale Univ Dept Chem & Environm Engn New Haven CT 06511 USA Yale Univ Energy Sci Inst New Haven CT 06511 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China Natl Renewable Energy Lab Golden CO 80401 USA

A TiO2 coating was grown on a CdTe absorber by atomic layer deposition for stabilization against its photocorrosion during photoelectrochemical water splitting. Under simulated sunlight (AM 1.5G, 100 mW cm(-2)), this multilayer CdS/CdTe/TiO2/Ni/NiOx photoanode produced a light-limited photocurrent density of 24.5 +/- 0.5 mA cm(-2) and a photovoltage of 780 +/- 20 mV. This record energy-conversion performance was comparable to those of baseline CdS/CdTe solar cells and was achieved only after the development of proper CdTe surface treatments prior to coating the stabilization layer. The TiO2 coating, with its in-gap charge-transport intermediate band, facilitates hole transport as light exits the CdTe/TiO2 interface. With proper interfacial chemistry, the electrochemical potential energy of the coating intermediate band matched that of the CdTe valence band. Moreover, the stabilized CdS/CdTe/TiO2/Ni/NiOx photoanodes showed 100 h stability for water oxidation under light-on/light-off cycles. This study provides insightful guidance for designing stabilization contacts for efficient and stable light-driven water oxidation.

关键词： Coating materials Photonics Oxides Layers Cadmium sulfide

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Development of a filtered interphase heat transfer model based on fine-grid simulations of gas-solid flows

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AICHE JOURNAL 2020年第1期66卷 e16755-e16755页

作者： Huang, Zheqing Zhang, Chi Jiang, Ming Zhou, Qiang Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Shaanxi Key Lab Energy Chem Proc Intensificat Xian Shaanxi Peoples R China Xi An Jiao Tong Univ Suzhou Inst Suzhou Peoples R China

The filtered interphase heat-transfer coefficient for coarse-grid simulations of gas-solid flows can be obtained via a correction (Q) to its microscopic counterpart. The numerical results show that a good linear correlation between Q and the subgrid drift temperature exists at various filtered solid volume fractions, filter sizes and Reynolds numbers, where the subgrid drift temperature is the correlation between the fluctuating temperature of the gas phase and the fluctuation of the gas volume fraction. Since Q can be determined solely by one subgrid quantity, closure for Q is directly pursued. It is found that Q correlates surprisingly well with the product of the filtered solid volume fraction and the filtered temperature difference between the two phases normalized by the filtered heat transfer at a larger scale than the considered coarse grid. A fitting correlation is formulated based on this observation, and its predictability is evaluated in an a priori test.

关键词： filtered interphase heat-transfer coefficient fine-grid simulation fluidization gas-solid flow subgrid drift temperature

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Phenomenon of fog formation and flow characteristics of droplet-vapor-gas mixture in a cooler-condenser

Phenomenon of fog formation and flow characteristics of drop...

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ASME 2019 International Mechanical engineering Congress and Exposition, IMECE 2019

作者： Gu, Hongfang Guo, Qiwei Li, Changsong Zhou, Qing State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi China

ISBN: (纸本)9780791859452

Fog formation occurs in the process of condensation in the presence of non-condensable gas if the bulk temperature is lower than its saturation temperature (supersaturated). The phenomena of fogging is the formation of small condensate particles mixing with the vapor/gas stream, which creates potential problems of the vapor/gas/condensate separation and environmental pollution. Therefore, understanding of fogging mechanism and prevention of fog droplet entrainment are one of technical concerns for design and operation of cooler-condensers in the process industry. This paper presents the experimental study and numerical simulation of shell-side condensation with fog formation using a mixture of steam/non-condensable gas. The experimental data were collected on the two tube bundles (modified plastic tubes and stainless steel tubes). Using a high-speed photograph technique, the phenomenon of fog formation and flow characteristics of vapor/droplet transport were recorded over a wide range of test conditions. The numerical analysis of film and dropwise condensation, fog formation and droplet particle transport were simulated using different tube geometry and material, and flow velocity of air/droplet mixture. Based on simulation results, a new droplet trapping parameter is proposed to assess the optimal parameters of heat exchanger structural and operation conditions. Comparisons show that the numerical analysis results have a good agreement with experimental data and observations. These findings provide fundamental approach to account for the effect of fog formation, film and dropwise condensation, and droplet transport crossflow in cooler-condensers. Copyright © 2019 ASME.

关键词： Drops

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Expression of SALL4 in the synovial tissue of refractory rheumatoid arthritis patients

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Rheumatology & Autoimmunity 2024年第1期4卷 59-61页

作者： Ru Fan Zeqiong Liang Yujie Bu Fen Zhang Xing Cen Yuqing Liu Fenping Lian Fengwu Chen Shengxiao Zhang Junwei Chen Department of Rheumatology The Second Hospital of Shanxi Medical UniversityTaiyuanChina State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'anShaanxiChina Key Laboratory of Cellular Physiology at Shanxi Medical University Ministry of EducationTaiyuanChina Shanxi Provincial Key Laboratory of Rheumatism Immune Microecology The Second Hospital of Shanxi Medical UniversityTaiyuanChina

To the Editor,Rheumatoid arthritis(RA)synovitis is characterized by synovial inflammation,characterized by synovial proliferation,neovascularization,and leukocyte infiltration into the joint space,1 leading to irreversible cartilage and bone damage.2 This synovial inflammation stimulates the formation of pannus,which is an invasive tumor-like mass,ultimately contributing to the pathogenesis of *** shares several similarities with cancer,including joint pain,swelling,and stiffness,which are accompanied by hypoxia in the synovial tissue and tumor environment.3 Spalt-like transcription factor 4(SALL4)plays an essential role in the occurrence and development of tumors.4 However,SALL4 expression in synovial tissue of RA is yet to be *** study aimed to investigate SALL4 expression in synovial tissue derived from patients with RA,using immunohistochemical techniques.

关键词： SALL4 patients inflammation

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Melt droplet fragmentation behavior during fuel-coolant interaction 18

Melt droplet fragmentation behavior during fuel-coolant inte...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Li, Gen Feng, Haobo Wen, Panpan Zhang, Jun Wang, Jinshi Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

During a severe accident of nuclear reactor, the fuel-coolant interaction occurs at the relocation stage of corium melt. Such a mode of contact can result in vigorous thermal interactions, intense steam generation and, potentially, steam explosions. The thermal processes, in their turn, largely depend on hydrodynamic behavior. When melt is pouring into coolant pool, the melt jet fragments into large droplets or blobs, named the primary breakup. The droplets or blobs will experience secondary breakup as a result of shock wave at steam explosion. Either the primary or secondary breakup is governed by interface hydrodynamic instabilities. The droplet size distribution, which affects fuel-coolant areas, is important for evaluating heat transfer and debris coolability. In this study, we modelled melt drops deformation and fragmentation using a meshless Lagrangian MPS method. Fragments amount and size distribution were compared under different Weber numbers, and fragments drag coefficient were also analyzed. The results indicate that the melt drops breakup process could be divided into two phases: initial deformation and fragmentation phase governed by flow inertial force and the subsequent fragments coalescence phase under the impact of fluid surface tension. Fragments amount increased in fragmentation phase but decreased in coalescence phase. A large amount of fragments has a normalized diameter of 0.01 - 0.03, but a small amount of large size fragments (d/d0 > 0.04) also appeared as the crescent-shaped melt broke up and small fragments coalesced. The drag coefficient decreased with time during drop deformation period, and then reached a stable value. It has no significant difference among cases with different Weber numbers. © 2019 American Nuclear Society. All rights reserved.

关键词： Hydrodynamics

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Numerical Investigation of the Thermal Response to Skin Tissue during Laser Lipolysis

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Journal of Thermal Science 2018年第5期27卷 470-478页

作者： CHEN Bin ZHANG Yue LI Dong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Laser lipolysis can effectively treat obesity and its associated diseases, such as hypertension, fatty liver, and hyperlipidemia. However, currently available invasive laser lipolysis, which transmits laser to a fiber-optic catheter inserted into the subcutaneous tissue for irradiation through an incision, may cause hematomas, infections, and empyrosis. The current study presents a novel, noninvasive approach for laser lipolysis, which directly irradiates the intact skin surface without an incision and preferentially targets adipose tissue at the near-infrared band. High laser energy is necessary to damage adipocytes; however, this may carbonate and burn the dermis. Therefore, the introduction of skin cooling is essential to avoid unwanted hyperthermal injury and improve the threshold of radiant exposure. In the current study, we investigated a novel noninvasive approach assisted with skin cooling by establishing a homogeneous multi-layer skin model. In this method, light propagation in the skin was simulated by using the Monte Carlo method. Skin cooling was employed before laser irradiation to protect the epidermis from thermal damage, which was treated as a boundary condition based on Newton's law. The numerical results showed that the photons were deposited in the adipose layer more than in the other layers. Laser can effectively destroy adipose tissue at an energy density of >200 J/cm^2 at 1210 nm wavelength, whereas at least 300 J/cm^2 is required at 1064 nm to achieve the same effect. In this experiment, at >5 s pulse width, the selectivity of adipose was not obvious. Moreover, the results indicated that 60 ms R134a or R404a spray can effectively reduce the temperature of the epidermis. R404a exhibited a stronger cooling effect than R134a. Cold air cooling at -10 °C for 10 s could effectively decrease the skin temperature, and deeper cooling could be achieved by cold air cooling compared with cryogen spray cooling.

关键词： laser lipolysis Nd：YAG laser multi-layer skin model skin cooling

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