检索结果-内蒙古大学图书馆

Study of Unforced Unsteadiness in Centrifugal Pump at Partial flow Rates

Journal of Thermal Science 2021年第1期30卷 88-99页

作者： YANG Jun XIE Tian LIU Xiaohua SI Qiaorui LIU Jun School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Fluid and Power Machinery(Xihua University) Ministry of EducationChengdu 610039China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang 212013China

In order to explore the unforced unsteadiness of centrifugal pumps,a 2-D frequency domain imaging display technology was used to study the development of these unsteady flow structures at partial flow *** results showed that,the unsteady flow field was not only affected by rotor and stator interaction,but also appeared an unforced unsteadiness with fundamental frequency of St≈0.23 around the impeller throat ***,as the flow rates decreased,this unsteady flow structure gradually weakened and *** the flow rate was reduced to 0.6 times of design flow rate,another two unforced unsteady flow structures with characteristic frequencies of St≈0.0714 and St≈0.12 began to appear in the same ***,with the operating condition smaller than design flow rate,the internal flow became more and more *** addition to the forced unsteadiness,the unforced unsteadiness which is not connected with the blade passage frequency became more and more obvious.

关键词： centrifugal pumps partial flow conditions pressure pulsations unforced unsteadiness 2-D frequency domain visualization method

来源：评论

学校读者我要写书评

暂无评论

An improved DSMC method for acoustic agglomeration of solid particles assisted by spray droplets

引用

INTERNATIONAL JOURNAL OF multiphase flow 2024年 176卷

作者： Zhao, Hao Fan, Fengxian Su, Junxu Hu, Xiaohong Su, Mingxu Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

The direct simulation Monte Carlo (DSMC) method was improved for describing the process of acoustic agglomeration assisted by spray droplets. The agglomeration and rebound as consequences of inter -particle collisions were modeled by considering all possible particle types, in particular, mixed -phase particles associated with the immersion and distribution mechanisms. Numerical predictions by the present method were validated by both analytical solutions and experimental data. The dynamic process of the acoustic agglomeration in terms of the size and type evolution as well as the evolution of number concentration of different particle types were examined. Results suggest that the strong interaction between the solid particles and the spray droplets causes the significant enhancement of acoustic agglomeration. Furthermore, the effect of frequency varying from audible to ultrasonic range on the acoustic agglomeration was evaluated. Overall, a better performance of acoustic agglomeration can be achieved at a lower frequency, regardless of addition of spray droplets. Agglomeration efficiency of 64.8 % can be achieve at acoustic frequency of 1000 Hz in case with spray droplets. This study provides not only a numerical model for describing the agglomeration of complex particles in particleladen gas flows, but also important insights into the acoustic agglomeration assisted by spray droplets.

关键词： Direct simulation Monte Carlo (DSMC) method Acoustic agglomeration Mixed-phase particle Particle-laden gas flow Numerical simulation Model validation

来源：评论

学校读者我要写书评

暂无评论

Molecular dynamics investigation on structural and interfacial characteristics of aerosol particles containing mixed organic components

引用

ATMOSPHERIC ENVIRONMENT 2024年 319卷

作者： Zhang, Chao Zhang, Zhichao Xiong, Wei Yang, Yang Wang, Yueshe Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Microscopic morphology plays a significant role in the description of aerosol particle evolution, but the knowledge on particles containing mixed organic matters is insufficient. In this study, molecular simulation (MD) method is employed to investigate the morphologies of particles containing two or three of malonic acid (MA), adipic acid (AA) and eicosane (C20). The key point is the effects of organic species and water content on structural and interfacial characteristics of particles. Results show that all dry particles exhibit the approximate core-shell structure with the shell composed of organic with longer hydrocarbon chain. With water content increasing from 100 to 1000, MA + AA + H2O particles present the core-shell structure with decreasing MA in the core, while particles containing C20 successively exhibit the core-shell structure and the ball-cap structure with three layers. These structural differences are caused by the surface propensity of organics, which is positively correlated with both the length of hydrocarbon chain and the water content. At the particle surface, hydrophobic groups of organic molecules direct towards the gas phase. MA (AA) located between water droplet and C20 cluster orient their hydrophobic groups toward C20. Furthermore, ratios of hydrophilic and hydrophobic atoms (K) at the surface of all studied particles increases with increasing water content, and at each water content the order is K(MA + AA) > K(MA + AA + C20) > K(AA + C20) > K(MA + C20). These findings provide microscopic information support for the development of theoretical model for the particle formation and growth.

关键词： Aerosol particles Microscopic structure Interface Molecular dynamics simulation

来源：评论

学校读者我要写书评

暂无评论

Characterization of a distributed Joule-Thomson effect cooler with pillars

引用

INTERNATIONAL JOURNAL OF ENERGY RESEARCH 2021年第9期45卷 13965-13977页

作者： Geng, Hui Cui, Xiaoyu She, Hailong Chang, Zhihao Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai Peoples R China

The application of general Joule-Thomson (J-T) coolers in the integrated electronic equipment is limited by its compactness in the heat exchanger and cooling power (a few milliwatts to hundreds of milliwatts). However, the microchannel with pillars has many advantages, such as compact structure, tiny axial thermal conductivity, and large heat transfer area. Besides, when the pressure variation of the fluid is large in the microchannel, the distributed Joule-Thomson effect is generated significantly. Therefore, this study proposed a throttling and heat exchange structure, where heat transfer and throttling coexisted, and fabricated a laminated microchannel distributed J-T cooler with pillars utilizing the processing technology of printed circuit heat exchanger. The refrigeration performance concerning the cold-end temperature, cooling power, and temperature distribution was then investigated through experiments with two refrigerants (argon and nitrogen). The study implies that the temperature difference and cooling power of the cooler both increase with the rise of the inlet pressure with argon, the no-load cold-end temperature is 166.1 K, and the gross cooling power is 3.83 W at 5.20 MPa. The temperature of the cooler increases with the rise of heat load, while the parasitic heat load decreases. The cold-end temperature is 186.0 K, then the parasitic heat load and the gross cooling power are respectively 3.17 W and 7.17 W at 5.20 MPa under the heat load's condition of 4 W. Comparing the refrigeration performance of nitrogen and argon, the cold-end temperature of nitrogen at 5.20 MPa is 235.7 K, which is close to that of argon at 2.98 MPa. Whereas the cooling time of nitrogen is slightly shorter than that of argon, and the cooling power is 3.10 W, higher than that of argon. In addition, this study provides new insight into increasing the cooling power and reducing the application cost of miniature coolers.

关键词： cooling power distributed Joule‐ Thomson effect microchannel PCHE pillars

来源：评论

学校读者我要写书评

暂无评论

Depth from Defocus Technique for High Number Densities and Non-Spherical Particles

SSRN

引用

SSRN 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

来源：评论

学校读者我要写书评

暂无评论

Enhanced catalytic activity for simultaneous removal of PCDD/Fs and NO over carbon nanotubes modified MnO_(x)-CeO_(2)/TiO_(2)catalyst at low temperatu

引用

Waste Disposal and Sustainable Energy 2021年第1期3卷 63-71页

作者： Qiulin Wang Zhuping Jiang Jianjian Zhou Jin Jing School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Henan Diesel Engine Industry Co LtdLuoyang 471000China

Simultaneous catalytic removal of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)and nitrogen oxides(NO_(x))emission at low temperature is of great significance to solve the multiple air pollution problem caused during waste incineration.A novel catalyst with excellent low-temperature activity towards PCDD/Fs catalytic decomposition,as well as selective catalytic reduction(SCR)of NO with NH_(3)is urgently needed to simultaneously control PCDD/Fs and NO ***-cerium composite oxides supported on titanium dioxide(MnO_(x)-CeO_(2)/TiO_(2))or TiO_(2)and carbon nano-tubes(CNTs)composite carrier(MnO_(x)-CeO_(2)/TiO_(2)-CNTs)were prepared using sol-gel method,and their catalytic activity towards simultaneous abatement of ortho-dichlorobenzene(o-DCBz,model molecular to simulate PCDD/Fs)and NO was *** comparison with their removal,the simultaneous removal efficiencies of o-DCBz and NO over MnO_(x)-CeO_(2)/TiO_(2)catalyst are lowered to 27.9%and 51.3%at 150℃under the gas hourly space velocity(GHSV)of 15,000 h−1,due to the competition between the reactants for the limited surface acid sites and surface reactive oxygen *** addition improves the catalytic activity for their simultaneous *** optimum condition occurs on MnO_(x)-CeO_(2)/TiO_(2)combined with 20 wt.%CNTs that above 70%of o-DCBz and NO are removed *** results reveal that MnO_(x)-CeO_(2)/TiO_(2)-CNTs catalyst with proper CNTs content has larger Brunauer-Emmet-Teller surface area and greatly improved surface acidity property,which are beneficial to both o-DCBz and NO ***,the relatively higher surface atomic concentration of Mn^(4+)as well as the existence of abundant surface Ce^(3+)atom accelerates the redox cycle of the catalyst and enriches the surface reactive oxygen *** the above factors alleviate the competition effect between o-DCBz catalytic oxidation and NH_(3)-SCR reaction and are conducive to the simulta

关键词： o-DCBz catalytic oxidation Simultaneous removal MnO_(x)-CeO_(2)catalyst Composite carrier Carbon nanotube

来源：评论

学校读者我要写书评

暂无评论

The proposal and calculation method of the annular domain weight function for the electromagnetic flowmeter under annular conductivity distribution

引用

flow MEASUREMENT AND INSTRUMENTATION 2024年 100卷

作者： Yang, Yang Yang, Biaohu Zhang, Chao Yang, Bin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Researching on the characteristic of weight function distribution under non-uniform conductivity distribution is of significant importance for expanding the engineering applications of electromagnetic flowmeter. In this paper, the characteristic of weight function distribution is firstly explored for annular conductivity distribution where the center and outer ring are both conductive. The research results indicate an important finding that the average value of the weight function within any small annular domain of the center or outer ring remains constant as the radial position changes. Therefore, the concept of 'annular domain weight function' is then innovatively proposed. Furthermore, the relationship is studied between the ratio of the annular domain weight function of the center and outer ring and the annular feature parameters. Ultimately, the correlations are obtained for calculating the annular domain weight functions of the center and outer ring.

关键词： Electromagnetic flowmeter Weight function Annular conductivity distribution Annular domain weight function

来源：评论

学校读者我要写书评

暂无评论

Multiscale study of reactive transport and multiphase heat transfer processes in catalyst layers of proton exchange membrane fuel cells

引用

CARBON NEUTRALITY 2024年第1期3卷 14页

作者： Zhang, Ruiyuan Chen, Li Min, Ting Mu, Yu-Tong Hao, Liang Tao, Wen-Quan Xi An Jiao Tong Univ Key Lab Thermo Fluid Sci & Engn MOE Sch Energy & Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Human Settlements & Civil Engn Xian 710054 Shaanxi Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Improving the performance of proton exchange membrane fuel cells (PEMFCs) requires deep understanding of the reactive transport processes inside the catalyst layers (CLs). In this study, a particle-overlapping model is developed for accurately describing the hierarchical structures and oxygen reactive transport processes in CLs. The analytical solutions derived from this model indicate that carbon particle overlap increases ionomer thickness, reduces specific surface areas of ionomer and carbon, and further intensifies the local oxygen transport resistance (R other). The relationship between R other and roughness factor predicted by the model in the range of 800-1600 s m-1 agrees well with the experiments. Then, a multiscale model is developed by coupling the particle-overlapping model with cell-scale models, which is validated by comparing with the polarization curves and local current density distribution obtained in experiments. The relative error of local current density distribution is below 15% in the ohmic polarization region. Finally, the multiscale model is employed to explore effects of CL structural parameters including Pt loading, I/C, ionomer coverage and carbon particle radius on the cell performance as well as the phase-change-induced (PCI) flow and capillary-driven (CD) flow in CL. The result demonstrates that the CL structural parameters have significant effects on the cell performance as well as the PCI and CD flows. Optimizing the CL structure can increase the current density and further enhance the heat-pipe effect within the CL, leading to overall higher PCI and CD rates. The maximum increase of PCI and CD rates can exceed 145%. Besides, the enhanced heat-pipe effect causes the reverse flow regions of PCI and CD near the CL/PEM interface, which can occupy about 30% of the CL. The multiscale model significantly contributes to a deep understanding of reactive transport and multiphase heat transfer processes inside PEMFCs. A particle-overlapping mo

关键词： Catalyst layer Low Pt loading Carbon particle overlap Local transport resistance Multiscale modeling

来源：评论

学校读者我要写书评

暂无评论

High-efficiency reactor and its tandem module with Au-Co-CoOx-coated glass beads for continuous-flow reduction of dyeing wastewater

引用

REACTION CHEMISTRY & engineering 2023年第8期8卷 1981-1992页

作者： Sun, Li Sun, Mengying Zhi, Yuan Zhang, Hua Shan, Yuejin Dou, Binlin Chen, Jian Zhang, Lixin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Jun Gong Rd 516 Shanghai 200093 Peoples R China Shanghai Minrula Biotechnol Co Ltd R&D Dept Bldg 15 Haji Sixth Rd 218 Shanghai 201306 Peoples R China Utsunomiya Univ Dept Mat & Environm Chem Res Div Funct Mat Design Yoto 7-1-2 Utsunomiya 3218585 Japan

The continuous-flow (C-F) reduction process has been limitedly applied in the treatment of dyeing wastewater owing to the weak catalytic performance of the reactors employed. In this work, a small tubular packed reactor and its module are designed, fabricated and used for the C-F reduction of nitro and azo compounds in dyeing wastewater. Here, Au-Co-CoOx-coated glass beads with superior catalytic activity are chosen as packing materials, prepared without any toxic chemical agents. By means of the reactor, 4-nitrophenol (4-NP) can be completely removed and its removal rate is determined to be 100 & mu;mol h(-1). After that, a novel strategy for the tandem module is proposed to further enhance the removal rate of 4-NP. Based on the tandem module, the removal rate of 4-NP can be dramatically boosted to 1900 & mu;mol h(-1). Meanwhile, the rate constant for the C-F reduction of 4-NP can reach up to 0.44 s(-1). Furthermore, the tandem module displays satisfactory operating stability, reusability and reliability in real water samples. In addition, the tandem module first achieves the C-F reduction of 2-nitrophenol, 3-nitrophenol, methyl red and methyl orange. Clearly, the reactor and its module can effectively extend the application of the C-F reduction process in dyeing wastewater treatment.

关键词： Wastewater treatment

来源：评论

学校读者我要写书评

暂无评论

Thermodynamic analysis of a solid oxide electrolysis cell system in thermoneutral mode integrated with industrial waste heat for hydrogen production

引用

ENERGY 2024年 301卷

作者： Wu, Chenxi Zhu, Qunzhi Dou, Binlin Fu, Zaiguo Wang, Jikai Mao, Siqi Shanghai Univ Elect Power Coll Energy & Mech Engn Shanghai 201306 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

In this study, a widely applicable hydrogen production system based on solid oxide electrolysis cells (SOEC) is proposed for industrial waste heat recovery. When the thermoneutral mode is employed to maintain the isothermal state of SOEC, the performances of a single SOEC and the system are comprehensively analyzed respectively. The results show that an increase in SOEC temperature leads to a rise in current density, power, hydrogen production, and inlet steam flow rate. Conversely, as the steam conversion rate rises, these parameter values decrease. A set of 3D performance maps are provided to illustrate parameter variations. The thermoneutral data of SOEC can be utilized in various systems, not limited to the proposed one. Increasing the steam conversion rate improves energy efficiency and energy consumption performance of the system, but decreases the inlet steam flow rate and production capacity. A temperature rise improves the inlet steam flow rate and production capacity but has a slight effect on energy efficiency and energy consumption performance. When the inlet steam flow rate is 50 kg/h and the temperature is 800 degrees C, the system achieves a maximum hydrogen production of 2.473 kmol/h. The proportion of waste heat supply to total energy consumption fluctuates between 15.5 % and 20.6 % across the operation conditions. It shows great potential for hydrogen production utilizing industrial waste heat. Meanwhile, the stack consumes almost all of the electrical energy.

关键词： Thermodynamic analysis SOEC Waste heat recovery Thermoneutral mode Hydrogen production

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：