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11th Asia-Pacific Conference on Combustion, ASPACC 2017

作者： Cai, Xiao Wang, Jinhua Zhao, Haoran Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University NO.28 Xianning West Road Xi’an710049 China

An experimental study on flame front evolution and self-acceleration of hydrogen spherically expending flames was conducted on a constant volume combustion chamber over a wide range of Lewis number at elevated pressures. Flame morphology, onset of flame acceleration and flame self-similar acceleration were analyzed. The results shows that the critical radius for onset of flame acceleration increases with the increase in effective Lewis number and the decrease in initial pressure. And the critical Peclet number increases nonlinearly with the increasing Markstein length. Thus, the onset of flame acceleration is controlled by the couple effects of hydrodynamic and diffusional-thermal instabilities. Furthermore, the self-similar acceleration exponent increases with the decrease in the effective Lewis number (or Markstein number) and almost keeps constant with initial pressure. It is concluded that the self-similar acceleration exponent is mainly affected by diffusional-thermal instability. © 2018 Combustion Institute. All Rights Reserved.

关键词： Acceleration

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Anti-K salt poisoning of MnO x catalyst via X (X = Ce, Sm and Er) oxides for low-temperature NH 3 -SCR of NO and oxidating CO

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Journal of Environmental Chemical engineering 2025年第3期13卷

作者： Liang Wang Shan Ren Xiaodi Li Chi He Chunli Zheng Xinzhe Li Shouning Chai Kejiang Li Chunbao Charles Xu College of Materials Science and Engineering Chongqing University Chongqing 400044 PR China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 PR China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 PR China School of Energy and Environment City University of Hong Kong Kowloon Hong Kong

Manganese oxide (MnO x ) serves as an effective catalyst for the simultaneous elimination of NO and CO pollutants in low-temperature flue gas. However, potassium salts present in industrial flue gas severely compromise the catalytic performance by altering surface physicochemical properties, leading to deactivation and reduced pollutant removal efficiency. To address this limitation, several rare earth (Ce, Sm and Er) oxides were incorporated into MnO x catalyst to enhance active site under potassium (K) exposure in this work. Catalytic activities of NO and CO removal both followed the order of K-Sm/MA > K-Er/MA > K-Ce/MA > K/MA. Especially, Sm/MA enhanced the considerable conversion of NO and CO at 175°C. Characterization revealed that Sm optimized the ration of Mn 4 + and O α , which showed higher active sites than other rare earth oxides modification. Moreover, in situ DRIFTS analysis confirmed the enhanced fast SCR process and the stronger interaction between CO and active sites on K-Sm/MA catalyst, which contributed to its superior K resistance and improved the removal efficiency. The K-Sm/MA catalyst accumulated more nitrate species and exhibited good reactivity, sustaining continuous NO conversion through the Langmuir-Hinshelwood (L-H) mechanism. Finally, a pathway model of Sm oxide on MnO x catalyst for the simultaneous NH 3 -SCR coupling CO oxidation at K poisoned situation.

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Heat Transfer Enhancement of Supercritical Carbon Dioxide and Liquid Lead Bismuth Eutectic Compact Heat Exchanger 20

Heat Transfer Enhancement of Supercritical Carbon Dioxide an...

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20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023

作者： Liu, Shuhan Liu, Ji'an Liu, Qingjiang Lei, Xianliang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 West Xianning Road Xi'an710049 China

ISBN: (纸本)9780894487934

Lead cooled fast reactor (LFR) is the fourth generation reactor system with great development potential;Supercritical carbon dioxide (S-CO2) Brayton cycle is also considered as the most promising energy system due to its high efficiency and compactness, good flexibility. Their combination is undoubtly considered as one of the most ideal power cycles. In this union system, the intermediate heat exchanger plays a key role in the entire power system. Considering the thermo-physical properties and heat transfer behaviors in both S-CO2 and liquid lead bismuth eutectic (LBE) are significantly different, an asymmetric compact coupled heat exchanger learning from Honeycomb structure is proposed. Then the effect of Reynolds number on the coupling heat transfer is discussed. It is found that the thermal resistance mainly exists in the cold side. In order to enhance the heat transfer in the S-CO2 side, wave channels are used on the cold side. The results show that the wave channels can significantly improve the field synergy of the fluid near the wall;With the increase of wave amplitude, the heat transfer coefficient and the friction factor of the cold side channel increases;The comprehensive heat transfer coefficient PEC is used to evaluate the heat transfer behavior. When the PEC number is the largest, the overall heat transfer coefficient of the heat exchanger is 1.56~1.81 of the straight channel in the range of Re=86700~145000. © 2023 Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. All rights reserved.

关键词： Brayton cycle

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Numerical computation of aerodynamic noise reduction by using ultra-light porous metals

Numerical computation of aerodynamic noise reduction by usin...

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International Conference on Transportation engineering

作者： Liu, Hanru Wei, Jinjia State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an China Xi'An Jiaotong University Xi'an 710049 China

ISBN: (纸本)9780784411841

As the speed of high-speed train (HST) increases continuously, aerodynamic noise has become more important compared with the wheel/rail noise, which affects the inhabited environment around the railway and the comfort of passengers. This paper preliminarily investigates the feasibility of reducing the low Mach number aerodynamic noise by using ultra-light porous metals. The noise generated by the flow around a two-dimensional circular cylinder which is the typical unit of pantographs, was simulated with and without a porous media. The hybrid method that combines large eddy simulation (LES) with Ffowcs Williams-Hawkings (FW-H) equation was employed. The calculated overall sound pressure level (OASPL), vortex shedding frequency and time-average drag coefficient agree well with available experimental data. Then, the effects of porosity and the speed of train on the aerodynamic noise were predicted and explained in view of fluid mechanics. The numerical results indicate that the open cell-type porous media with high porosity can modify and regularize the fluid flow, adjust the vortex shedding frequency, leading to a significant reduction of aerodynamic noise. © 2011 ASCE.

关键词： Porous materials

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Construction of Pd-M （M = Ni, Ag, Cu） alloy surfaces for catalytic applications

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Nano Research 2018年第2期11卷 780-790页

作者： Xiang Li Xixi Wang Maochang Liu Hongyang Liu Qiang Chen Yadong Yin Mingshang Jin Frontier Institute of Science and Technology (FIST) School of Chemical Engineering and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing China Department of Chemistry University of California Riverside USA

The fabrication of ultrathin alloy shells as heterogeneous catalysts to increase the utilization efficiency and enhance the catalytic activity of metal atoms has been recognized as an effective method for the construction of efficient metal nanocatalysts, particularly noble-metal nanocatalysts. In this study, we demonstrate the successful formation of Pd-M （M = Ni, Ag, Cu） alloy shells with a tunable thickness on preformed nanoscale Pd seeds. The success of this synthesis mainly relies on the combination of the slow reduction of ＂M＂ ions and the subsequent diffusion of M ad-atoms into the surface lattice of Pd seeds. The composition of the Pd-M alloy shell is easily tuned by changing the type and amount of the added precursor, and the shell thickness is manipulated according to the reaction time. More significantl the surface structure of these alloy shells is maintained after the reaction, implying that any desired surface structure of Pd-M alloy shells can be prepared by using the appropriate starting materials. Further catalytic evaluation of the hydrogenation of chloronitrobenzenes shows that these alloy surfaces exhibit significantly improved selectivity compared to the Pd seeds. The Pd-Ni alloy surfaces exhibit much better catalytic selectivity （as high as 〉 99%） than Pd catalysts.

关键词： Pd allo3 catalyst shape control hydrogenation

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Synthesis of uniform ZnO/ZnS/CdS nanorod films with ion-exchange approach and photoelectrochemical performances

Synthesis of uniform ZnO/ZnS/CdS nanorod films with ion-exch...

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作者： Jiang, Jiangang Wang, Meng Ma, Lijing Chen, Qingyun Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering International Research Center of Renewable Energy Xi'An Jiaotong University Shaanxi 710049 China

The uniform ZnO/ZnS/CdS core-shell nanorod film was synthesized by a two-step ion-exchange method. The crystal structure, morphology, composition and optical property of as-prepared films were characterized by X-ray diffraction (XRD), Raman, Scanning electron microscope (SEM), Transmission electron microscope (TEM), Energy dispersive X-ray Detector (EDX) and UV-vis techniques. The results showed that the ZnO nanorod arrays can be used as sacrificial templates to synthesize uniform ZnS layer and further transform into CdS by simple ion-exchange approach. The CdS content in the films can be adjusted easily by changing the reaction temperature. The intimate contact between core and shell can be observed by high-resolution TEM image, which decrease the crystal boundary potential barrier and then facilitate the photogenerated charges transfer between the different phases. In this experiment, the ZnO/ZnS/CdS nanorod films were used in the photoelectrochemical (PEC) hydrogen production. And it is found that the film prepared at 70 C (first step) and 100 C (second step) gives a maximum photocurrent density and photo conversion efficiency. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Cadmium sulfide

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Dryout point prediction model for bilaterally heated vertical narrow annuli under low flow conditions

Dryout point prediction model for bilaterally heated vertica...

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25th Annual CNS Conference - Nuclear Energy: Meeting the Challenges

作者： Myint, Aye Tian, Wenxi Li, Zhihui Hao, Li Jia, Dounan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an City 710049 China

ISBN: (纸本)0919784798

Prediction of dryout point was experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annular with narrow gap was bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux of 60.39 to 135.6 kg/m2 and heat flux of 5 to 50 kW/m2 This paper presents a new analytical model for the prediction of dryout point for steam- water flow in narrow annular gap and bilaterally and uniformly heated tubes. The prediction of dryout point for bilaterally heated annuli was based on the droplet-diffusion model for internally heated annuli by Kirillov and Smogalev (1969, 1972). The dryout model prediction values are compared with a experimental data, showing a good agreement in accuracy for the above mentioned parametric range.

关键词： Nuclear power plants

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NUMERICAL SIMULATION OF SINGLE/TWO-PHASE flow IN A STRATIFIED POROUS BED 31

NUMERICAL SIMULATION OF SINGLE/TWO-PHASE FLOW IN A STRATIFIE...

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2024 31st International Conference on Nuclear engineering, ICONE 2024

作者： Bouloudenine, Aimad Li, Liangxing Xiang, Zutao Shi, Shang Bakar, Muhammad Abu Xi’an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xianning West Road 28 Xi’an City710049 China

ISBN: (纸本)9780791888292

This study investigates the coolability of debris beds formed from Fuel-Coolant Interactions (FCI) within nuclear reactors, a critical safety concern when cooling systems fail, leading to significant core melting in light-water reactors. The research focuses on understanding the flow dynamics within two-layer stratified porous beds, which develop from the mixture of corium and coolant, particularly around the interface between layers. Using ANSYS Fluent software, numerical simulations were conducted to estimate velocity profiles and pressure drops across a stratified porous structure. The Euler-Euler two-fluid model was employed alongside the k-ω-based Shear Stress Transport (SST) turbulence model to separately model turbulence for each phase. The results reveal that lateral flow dynamics are significant as fluids traverse through the porous media, affecting pressure drops across layers with varying permeabilities. Specifically, the pressure drops across the lower-permeability layer decrease while that across the higher-permeability layer increases, highlighting the influence of lateral flows between layers of different particle sizes due to variations in porosity. This lateral flow is most likely formed during the initial stages of fluid movement through the bed. The study underscores the importance of understanding these flow characteristics for both single/two-phase flow to enhance the safety and design of nuclear reactors by improving debris bed coolability predictions. Copyright © 2024 by ASME.

关键词： Computational fluid dynamics

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Study on the gasification mechanisms of key intermediates of oily sludge in supercritical water by ReaxFF-MD method

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Energy 2025年 330卷

作者： Linhu Li Pai Peng Gaoyun Wang Xujun Li Wen Cao Zhengjun Gong School of Environmental Science and Engineering Southwest Jiaotong University Chengdu 611756 China State Grid Jiangsu Electric Power Co. Ltd. Research Institute Nanjing 211103 China Technical Inspection Center Sinopec Shengli Oilfield Company Dongying 257000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Supercritical water gasification has been confirmed as an advanced treatment method for organic waste including oily sludge. As a supplement to our previous studies, molecular dynamics (MD) simulations must be implemented to understand the gasification mechanism thoroughly. Five representative model compounds were selected to investigate the gasification mechanism using ReaxFF-MD method. The molecular evolution of five key intermediates in SCWG was simulated and compared at 3500 K. To overcome the gasification challenge of oily sludge, toluene was selected for further investigation due to its prominent proportion and relatively low reactivity. Simulations were systematically discussed under different temperatures (2500–3500 K) to study the product distribution. It was found that the yields of the main products (H 2 , CO and CO 2 ) continuously increased with reaction time and temperature. The yields of C1-C3, C4-C7 and C7+ increased more rapidly at higher temperature, with the yield of short-chain carbonaceous organics (C1-C3) being significantly higher than that of other carbonaceous organics. The decomposition kinetics of toluene in supercritical water were also analyzed, and the apparent activation energy was 235.22 ± 22.66 kJ⋅mol −1 . Furthermore, four main gasification pathways were identified by tracking molecular animations. This study would provide valuable insights into the transformation characteristics of oily sludge.

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Hydrogen production from sludge in supercritical water and its energy evaluation

Hydrogen production from sludge in supercritical water and i...

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5th International Energy Conversion engineering Conference

作者： Qinming, Zhang Shuzhong, Wang Liang, Wang Donghai, Xu Lingling, Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Thermal Engineering Xi'an Jiaotong University AIAA

ISBN: (纸本)1563479028

Gasification of high moisture content biomass in supercritical water has been identified as a promising alternative system for producing renewable hydrogen. Supercritical water partial oxidation is the process by which an oxidant appears during the reaction. The key advantage of this process is the rapid heating of the gasification medium, resulting in less char formation and improved hydrogen yield. Many researchers have studied the supercritical water gasification of model compounds. However, real biomass which is of importance for large production of hydrogen has yet to be thoroughly examined. In this paper, gasification of high moisture content municipal sludge was studied in a continuous reactor employing hydrogen peroxide as an oxygen source. The reaction was tested across temperatures and pressures in the range of 673 to 873 K and 24 to 30 MPa, and across various residence times ranging from 3 to 15 minutes. We found that sludge at low concentrations can be completely gasified with no observable char or tar formation. The improvement of gasification efficiency by partial oxidation was accompanied with a high yield of hydrogen and carbon monoxide. Through this, we evaluated the energy efficiency of sludge gasification. Our thermodynamic calculations show that the energy efficiency reaches 50% when considering hydrogen, carbon monoxide, and methane as the valuable gases in the ideal case. Taking into account the energy recovery from the hot water at 30 MPa and 873 K and assuming the ideal scenario of no external heat loss, the overall energy yield potentially reaches 85%. Our results show that the key mechanism of the gasification process is energy recovery, as the chemical reaction is endothermic and requires high temperatures.

关键词： Hydrogen production

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