检索结果-内蒙古大学图书馆

A mechanistic model for the prediction of swirling annular flow pattern transition

CHEMICAL engineering SCIENCE 2019年 199卷 405-416页

作者： Liu, Li Bai, Bofeng Shanghai Jiao Tong Univ Sch Nucl Sci & Engn Shanghai 200240 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

The accurate prediction of flow patterns and their transition is extremely important for proper design, operation and optimization of two-phase flow systems, since the parameters such as pressure loss and heat and mass transfer are strongly dependent on the flow pattern. So far, the non-swirling gas-liquid flow in straight pipes have been widely studied and various mechanisms that lead to flow pattern transition have been clarified and modeled. However, the dynamics of gas-liquid flow under swirling condition are not well understood, and no detailed models are available for the prediction of swirling flow pattern transition. To address this, in our previous work (Liu and Bai, 2018), a visualization experiment aimed at classifying flow regimes in swirling gas-liquid flow was presented and three typical swirling flow regimes, i.e., swirling gas column flow, swirling intermittent flow and swirling annular flow were classified and defined, respectively. As the swirling annular flow can be regarded as a special case of conventional annular flow (i.e., when tangential velocity does not equal zero), in present paper, a mechanistic model for the prediction of the swirling annular flow pattern transition was developed considering its physical interest and great practical significance. Two physical mechanisms that lead to the transition from swirling annular flow to other flow patterns were revealed and modeled, respectively. The model was evaluated against a wide range of swirling and non-swirling experimental data and based on this model, the effects of different parameters (e.g., hydraulic diameter, working pressure and swirl angle) on the boundary of flow pattern transition were presented. Results revealed that the range of swirling annular flow enlarges with the increase of the working pressure and swirl angle but narrows with the hydraulic diameter. Taking these influencing factors into account, a generalized formula for the prediction of the swirling annular flow patte

关键词： Gas-liquid flow Swirling annular flow flow pattern transition Mechanistic model

来源：评论

学校读者我要写书评

暂无评论

Optimization of sensitivity analysis in best estimate plus uncertainty and the application to large break LOCA of a three-loop pressurized water reactor

引用

PROGRESS IN NUCLEAR ENERGY 2020年 126卷 103396-103396页

作者： Xiong, Qingwen Gou, Junli Mao, Huihui Shan, Jianqiang Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Nucl Power Inst China Chengdu 610041 Peoples R China

The best estimate plus uncertainty (BEPU) methodology is developed to carry out realistic safety analysis of the nuclear power plant. However, the sensitivity analysis in the conventional methodologies often leads to inaccurate results when lacking of the phenomenon identification and ranking table (PIRT) or adopting the local sensitivity analysis methods. As the initial inputs determined in short of the PIRT may neglect some important parameters or identify some unimportant parameters, and the local methods are not appropriate for complex and non-linear systems. In this study, an optimized moment-independent global sensitivity analysis method with very low computational cost was utilized to improve the sensitivity analysis framework of the BEPU methodology. The reliability as well as the applicability of the method were assessed through some tests and a large break loss of coolant accident (LBLOCA) of the LOFT facility. The improved sensitivity analysis framework was then applied to the BEPU analysis of a typical three-loop pressurized water reactor CPR1000, and the reliability of the optimized moment-independent method was further confirmed by comparing the sensitivity analysis result of the method to the results of the BEMUSE project and the Spearman method. Besides, two new parameters were identified to have great influence on the PCT, and the two parameters should be taken into consideration in the uncertainty analysis of the BEPU methodology.

关键词： Sensitivity analysis BEPU Moment-independent PIRT LBLOCA

来源：评论

学校读者我要写书评

暂无评论

Design and R&D progress of Core Assembly Deformation Test Facility for China Demonstration Fast Reactor

引用

NUCLEAR engineering AND DESIGN 2019年第Jul.期348卷 65-77页

作者： Ma, Zehua Ma, Zhenhui Wu, Yingwei Gao, Fuhai Hei, Baoping Su, G. H. Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Shaanxi Key Lab Adv Nucl Energy & Technol Sch Nucl Sci & Technol Xian 710049 Shaanxi Peoples R China China Inst Atom Energy Beijing 102413 Peoples R China

China Demonstration Fast Reactor (CFR600) is under construction, and the Sub-assembly Deformation Analysis Program (SDAP) developed by China Institute of Atomic Energy is used to optimize the core design and operation management of CFR600. The Core Assembly Deformation Test Facility (CADTF), designed and built by Xi'an Jiaotong University, was selected to carry out a series of assembly bending and thermal bowing tests to provide validation problems for the SDAP. The specimen assembly was specially designed for better non-intrusive optical temperature measurement of the inner wrapper tube. The automatic heating control method and a lot of new measurement technology were applied into the tests to gain abundant and accurate test data.

关键词： Core Assembly Deformation Fast reactor Assembly thermal bowing test

来源：评论

学校读者我要写书评

暂无评论

Axial development of air-water annular flow with swirl in a vertical pipe

引用

INTERNATIONAL JOURNAL OF multiphase flow 2020年第0期124卷 103165-000页

作者： Liu, Wen Lv, Xiaofei Bai, Bofeng Changzhou Univ Jiangsu Key Lab Oil Gas Storage & Transportat Tec Changzhou 213000 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Annular flow with swirl induced by a swirler has been widely used in industry. Swirl decay which closely related to working performance and length of the flow is significantly important for its application in industry. Axial development of annular flow with and without swirl has been investigated in this work by means of experimentation and modelling. A vertical pipe system with 11 m long and 62 mm inner diameter was carried out to investigate axial development of flow pattern, void fraction and pressure drop in the annular flow with and without swirl. The experimental results show that a swirling annular flow with swirling streak and less disturbed waves is observed downstream of the swirler. Void fraction decreases, total pressure drop increases and the PDF (probability density function) of pressure drop becomes more concentrated in the annular flow with swirl, compared with these in the annular flow without swirl. However, swirling annular flow is gradually transformed to annular flow without swirl along the stream-wise direction. To qualitatively predict the decay in an annular flow with swirl, a simplified theoretical model was developed here. The results calculated with the theoretical model were in agreements with experimental results. The obtained results can be used in predicting working performance and length of devices, such as separators and heat exchangers. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Swirl Annular flow Gas-liquid two-phase Pressure drop Decay

来源：评论

学校读者我要写书评

暂无评论

Synthesis of Ce-doped magnetic biochar for effective Sb(V) removal: Performance and mechanism

引用

POWDER TECHNOLOGY 2019年 345卷 501-508页

作者： Wang, Li Wang, Jingyi Wang, Zixuan Feng, Jiangtao Li, Shanshan Yan, Wei Xi An Jiao Tong Univ Dept Environm Sci & Engn State Key Lab Multiphase Flow Power Engn Sch Energy & Power Engn Xian 710049 Shaanxi Peoples R China Virginia Polytech Inst & State Univ Dept Civil & Environm Engn Blacksburg VA 24061 USA

A novel Ce-doped magnetic biochar was successfully synthesized by chemical co-precipitation (Ce/Fe-CP-BC) and solvothermal methods (Ce/Fe-ST-BC) for efficient Sb(V) adsorption. The Ce/Fe-CP-BC exhibited a high adsorption capacity of 25.0 mg/g, which was two times and one order of magnitude higher than that of Ce/Fe-ST-BC and un-doped BC, respectively. The excellent adsorption performance of Ce/Fe-CP-BC maintained over a wide pH range or in the presence of coexisting anions. The adsorption results indicated that co-precipitation method was superior to solvothermal method and Ce oxide was the main contribution to Sb(V) adsorption enhancement. The combined results of TEM, XRD, FTIR and XPS revealed that Ce atom was successfully doped into the Fe3O4 structure and abundant hydroxyl groups were formed on the surface of Ce/Fe-CP-BC. The magnetic performance decreased after Ce doping, but Ce/Fe-CP-BC still showed good separation potential. Based on the results of batch experiments and physiochemical analyses, the underlying mechanisms controlling Sb(V) adsorption on Ce/ Fe-CP-BC involved the inner -sphere surface complexation, hydrogen bonding, electrostatic attraction and ligand exchange. Among them, the ligand exchange and the formation of Ce-O-Sb complex were the main contributions to the significant Sb(V) adsorption increment on Ce/Fe-CP-BC. All the results implied that Ce/Fe-CP-BC could be used as a promising adsorbent for antimonate decontamination. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Ce-doped Biochar Sb(V) adsorption Mechanism

来源：评论

学校读者我要写书评

暂无评论

Regulating Crystal Structure and Atomic Arrangement in Single-Component Metal Oxides through Electrochemical Conversion for Efficient Overall Water Splitting

引用

ACS APPLIED MATERIALS & INTERFACES 2020年第51期12卷 57038-57046页

作者： Zhang, Xiaoping Dong, Chung-Li Wang, Yiqing Chen, Jie Arul, Kumaravelu Thanigai Diao, Zhidan Fu, Yanming Li, Mingtao Shen, Shaohua Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Tamkang Univ Dept Phys New Taipei 25137 Taiwan King Abdullah Univ Sci & Technol KAUST Div Phys Sci & Engn PSE Thuwal 239556900 Saudi Arabia King Abdullah Univ Sci & Technol KAUST KAUST Catalysis Ctr KCC Thuwal 239556900 Saudi Arabia

Single-component transition-metal oxide (TMO: FeOx, NiOx, or CoOx) nanosheets grown on nickel foam (NF) were electrochemically optimized with Li ion (Na ion)-induced conversion reaction for bifunctional electrocatalysis. The optimum FeOx/NF-Li electrocatalyst exhibits low overpotentials of 239 mV for hydrogen evolution reaction and 276 mV for oxygen evolution reaction at a current density of 100 mA cm(-2). A two-electrode water splitting cell using FeOJNF-Li as both anode and cathode requires only 1.60 V to achieve a current density of 10 mA cm(-2). The impressive water splitting performance of the FeOx/NF-Li electrode is revealed to be attributed to Li-induced electrochemical conversion, which alters the crystal structure, creating more active sites for electrocatalytic reactions, as well as introduces O vacancies increasing the electron density and the intrinsic conductivity. More importantly, the atomic arrangement is regulated from tetrahedral Fe(Td) to octahedral Fe(Oh) coordination, which acts as catalytically active sites with reduced Gibbs free energy for the rate-determining steps. This electrochemical conversion reaction can be extended to other TMOs (i.e., NiOx/NF and CoOx/NF) for promoted electrocatalytic water splitting performances. This study provides an in-depth understanding on the nature of atomic and electronic structure evolution to promote the electrocatalytic activity.

关键词： water splitting bifunctional electrocatalyst transition metal oxides electrochemical conversion reaction crystal structure atomic arrangement

来源：评论

学校读者我要写书评

暂无评论

On the Effect of Thermal Processing on Sn Diffusion and Efficiency Enhancement in Hematite/FTO Photoanodes

引用

ECS JOURNAL OF SOLID state SCIENCE AND TECHNOLOGY 2022年第4期11卷 043001-043001页

作者： Rodriguez-Gutierrez, Ingrid Mourino, Beatriz Freitas, Andre L. M. Costa, Carlos A. R. Pires, Elcio L. Goncalves, Renato, V Vayssieres, Lionel Souza, Flavio L. Brazilian Ctr Res Energy & Mat CNPEM Natl Nanotechnol Lab LNNANO BR-13083970 Campinas Brazil Fed Univ ABC UFABC Ctr Ciencias Nat & Humans CCNH BR-09210580 Santo Andre SP Brazil Univ Sao Paulo Sao Carlos Inst Phys BR-13560970 Sao Carlos SP Brazil Xi An Jiao Tong Univ Int Res Ctr Renewable Energy IRCRE Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Estadual Campinas Inst Chem UNICAMP BR-13083970 Campinas SP Brazil

The frequently underestimated effects of "in air" thermal treatment processing conditions such as temperature, duration, and heating and cooling rates in the design and efficiency of photoelectrodes fabricated for academic studies onto the most common commercial transparent conductive glass substrate i.e. fluorine-doped tin oxide (FTO) were investigated by XRD, XPS, SEM, conductive AFM, electrochemical impedance spectroscopy (EIS) as well as direct current (DC) and photoelectrochemical (PEC) measurements. The PEC response of Hematite photoanode thin films consisting of short nanorods thermally treated at 400 degrees C and 800 degrees C upon fast or extended time conditions is inhibited by factors such as crystallinity, Sn diffusion, or substrate integrity. A "fast" thermal treatment in air at 750 degrees C provided the best synergy between charge transfer resistance, Sn-diffusion from the FTO substrate, nanorod dimensions, reduced recombination, improved charge separation and minimized substrate damage. This study does offer valuable fundamental and practical insights for a better understanding of the benefits and drawbacks of photoelectrode thermal processing, which is critical for the improvement of the PEC performance-reproducibility relationship for FTO-based solar water splitting systems and devices.

关键词： Nanorods

来源：评论

学校读者我要写书评

暂无评论

Mechanism and Kinetics Study on Low-Temperature NH3-SCR Over Manganese-Cerium Composite Oxide Catalysts

引用

INDUSTRIAL & engineering CHEMISTRY RESEARCH 2019年第51期58卷 22763-22770页

作者： Lin, Feng Wang, Qiulin Zhang, Jianchao Jin, Jing Lu, Shengyong Yan, Jianhua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Zhejiang Univ Inst Thermal Power Engn State Key Lab Clean Energy Utilizat Hangzhou 310027 Peoples R China

Titanium dioxide-supported manganese oxide and cerium oxide noted as MnOx/TiO2, CeO2/TiO2, and MnOx-CeO2/TiO2 were prepared by sol gel method and their low-temperature (<200 degrees C) catalytic activity toward selective catalytic reduction (SCR) of NO with NH3 were evaluated. The MnOx-CeO2/TiO2 catalyst exhibited optimal low-temperature performance that is nearly 98% of NO was abated below 200 degrees C. That is because MnOx/TiO2 combined with CeO2 improves redox ability and surface acidity of the catalyst, mainly due to the incorporation of Mn atoms into bulk CeO2 that creates active Mn-O-Ce structures. In situ Fourier transform infrared (FTIR) spectroscopy suggested that the coordinated NH3 on Lewis acid sites were favored to react with NO and the NH3-SCR over MnOx-CeO2/TiO2 catalyst mainly followed the E-R mechanism at 200 degrees C. Furthermore, the reaction rate constant and apparent activation energy of the NH3-SCR reaction on the MnOx-CeO2/TiO2 catalyst confirmed the promotional effects of Ce addition on the activity of Mn-based catalyst.

关键词： Catalysts Catalytic reactions Oxides Transition metals Adsorption

来源：评论

学校读者我要写书评

暂无评论

Three-Dimensional Thermal Simulations of 18650 Lithium-Ion Batteries Cooled by Different Schemes under High Rate Discharging and External Shorting Conditions

引用

ENERGIES 2021年第21期14卷 6986页

作者： Li, Yang Zhou, Zhifu Zhao, Jian Hao, Liang Bai, Minli Li, Yulong Liu, Xuanyu Li, Yubai Song, Yongchen Dalian Univ Technol Key Lab Ocean Energy Utilizat & Energy Conservat Minist Educ Dalian 116024 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Waterloo Dept Mech & Mechatron Engn 200 Univ Ave West Waterloo ON N2L 3G1 Canada

In this work, three-dimensional thermal simulations of single 18650 lithium-ion battery cell and 75 V lithium-ion battery pack composed of 21 18650 battery cells are performed based on a multi-scale multi-domain (MSMD) battery modeling approach. Different cooling approaches' effects on 18650 lithium-ion battery and battery pack thermal management under fast discharging and external shorting conditions are investigated and compared. It is found that for the natural convection, forced air cooling, and/or mini-channel liquid cooling approaches, the temperature of battery cell easily exceeds 40 degrees C under 3C rate discharging condition. While under external shorting condition, the temperature of cell rises sharply and reaches the 80 degrees C in a short period of time, which can trigger thermal runaway and may even lead to catastrophic battery fire. On the other hand, when the cooling method is single-phase direct cooling with FC-72 as coolant or two-phase immersed cooling by HFE-7000, the cell temperature is effectively limited to a tolerable level under both high C rate discharging and external shorting conditions. In addition, two-phase immersed cooling scheme is found to lead to better temperature uniformity according to the 75 V battery pack simulations.

关键词： lithium-ion battery thermal modeling cooling multi-scale multi-domain model external short circuit

来源：评论

学校读者我要写书评

暂无评论

Effects of surface subcooling on the spreading dynamics of an impact water droplet

引用

PHYSICS OF FLUIDS 2020年第12期32卷 123309-123309页

作者： Shang, Yuheng Zhang, Yuhui Hou, Yu Bai, Bofeng Zhong, Xin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Beihang Univ Natl Key Lab Sci & Technol Aeroengine Aerothermod Beijing 100191 Peoples R China

Spontaneous spreading of a liquid droplet upon a cold solid surface is ubiquitous in nature as well as critical to many industrial technologies, while the mechanism of which still remains elusive. The role of surface subcooling in a water droplet spreading behavior upon impacting on a smooth silicon surface has been experimentally investigated. Under the subcooling condition of the substrate, in the low Weber number region, the non-dimensional maximum spreading diameter decreases with the surface subcooling due to a larger viscosity dissipation and higher surface tension. However, in the case of a high Weber number, the maximum spreading factor first descends and then increases with the increasing surface subcooling. This non-monotonic tendency is attributed to the competition between the increased maximum fingering length and the reduced maximum interior spreading diameter with an increase of the surface subcooling. A sufficiently large Weber number is the prerequisite for forming fingering patterns, and a high subcooling reinforces them due to the enhanced deceleration caused by a larger surface tension and viscosity. The time at maximum spreading barely changes with the impact velocity and slightly decreases with the surface subcooling depending on the droplet size. An improved correlation of the time at maximum spreading as a function of the maximum spreading factor, droplet size, impact velocity, and surface subcooling is proposed.

关键词： Surface tension

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：