检索结果-内蒙古大学图书馆

Thermal characteristics and thermal stress analysis of a superheated water/steam solar cavity receiver under non-uniform concentrated solar irradiation

引用

APPLIED THERMAL engineering 2021年第Part2期183卷 116234-116234页

作者： Fang, Jiabin Zhang, Canghong Tu, Nan Wei, Jinjia Wan, Zhenjie Xi An Jiao Tong Univ Sch Chem Engn & Technol Xian 710049 Peoples R China Xian Polytech Univ Sch Mech & Elect Engn Xian 710048 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Solar cavity receiver is a vital component in a solar power tower (SPT) system, where concentrated solar irradiation is absorbed, converted into heat and carried away by a kind of heat transfer fluid. The cavity receiver usually suffers from the high-flux and non-uniform concentrated solar irradiation, which would cause local overheating, large temperature gradient and even thermal stress fracture of the receiver and bring challenges for the safety of its daily operation. Therefore, it is necessary to investigate the thermal and mechanical performance of the solar cavity receiver. In the present study, a superheated water/steam solar cavity receiver with three boiling panels and a superheater was chosen as the physical model. An integrated simulation method, which couples the Monte-Carlo ray tracing (MCRT) method, the appropriate heat transfer correlations, the finite volume method (FVM) and the finite element method (FEM), was employed to simulate the complicated heat transfer process inside the receiver and conduct the thermal stress analysis for the absorber panels. With this method, the three-dimensional wall temperature and thermal stress distributions were gained both on the boiling panels and the superheater, and the causes of thermal stress induced by different temperature gradients were analyzed in detail. The following results were obtained: 1) The heat flux, wall temperature and equivalent thermal stress distributions all appear highly non-uniform on the absorber panels;2) The hot spots can be found on the membrane wall between the elbows of the boiling panels, which can easily generate the high thermal stress due to the large temperature gradient with their surroundings;3) The bi-axial stress at the outer and inner radius of the boiling tubes can be created by the large radial temperature gradient, and the thermal stress varies as a cosine distribution across the circumference of the superheated tubes, which is induced by the large temperature gradient i

关键词： Solar cavity receiver Boiling panels Superheater Temperature gradient Thermal stress

来源：评论

学校读者我要写书评

暂无评论

Ion Migration as a New Paradigm to Boost Self-Driven Perovskite Narrowband Photodetectors

引用

ADVANCED OPTICAL MATERIALS 2023年第16期11卷

作者： Yu, Shanshan Li, Yu Wang, Jian Zhang, Kai Lin, Zedong Qian, Wei Deng, Ziqi Guo, Fumin Li, Mingde Vayssieres, Lionel Saidaminov, Makhsud I. Phillips, David Lee Yang, Shihe Peking Univ Sch Chem Biol & Biotechnol Shenzhen Grad Sch Guangdong Prov Key Lab Nanomicro Mat Res Shenzhen 518055 Peoples R China Inst Biomed Engn Shenzhen Bay Lab Shenzhen 518107 Peoples R China Univ Hong Kong Dept Chem Hong Kong 999077 Peoples R China South China Agr Univ Coll Mat & Energy Guangzhou 510642 Peoples R China Shantou Univ Dept Chem Shantou 515063 Peoples R China Shantou Univ Key Lab Preparat & Applicat Ordered Struct Mat Gua Shantou 515063 Peoples R China 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 Victoria Dept Chem 3800 Finnerty Rd Victoria BC V8P 5C2 Canada

Halide perovskite narrowband photodetectors based on a charge collection narrowing mechanism have emerged as a new class of optoelectronic devices for monochromatic imaging. However, improving the figures-of-merit of such narrowband photodetectors remains challenging due to the inability to manipulate the major material players in the elusive photoresponse process. Here, a novel approach of manipulating ion migration to enhance the narrowband photoresponse of self-driven p-i-n type photodetectors is taken by intentionally adding mobile ions into the formamidine and methylamine mixed cation perovskite layer. The excess mobile ions reduce the activation energy of ion migration, and this facilitated migration orchestrates the ions in the perovskite layer to re-engineer the energy band, and thus modulates the charge separation and collection energetics and kinetics, leading to an unprecedented boost of the narrowband photoresponse. The photodetector based on this approach achieved a peak responsivity of as high as 112.41 mA W-1 at 820 nm at zero bias with a full-width at half maximum of only 22 nm and an over 3-fold improvement in the spectral rejection ratio, making it highly promising for the next-generation color imaging devices.

关键词： ion migration narrowband response perovskites photodetectors quantum efficiency

来源：评论

学校读者我要写书评

暂无评论

Performance of Low-temperature SCR of NO with NH3 over MnOx/Ti-based catalysts

引用

CANADIAN JOURNAL OF CHEMICAL engineering 2019年第Sup1期97卷 1407-1417页

作者： Niu, Yanqing Zhang, Xiaolu Zhang, Hao Liang, Yang Li, Shuaifei Yao, Qi Wang, Denghui Hui, Shi'en Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China North China Elect Power Sci Res Inst Co Ltd Beijing 10045 Peoples R China

The effects of Mn loadings and precursors, catalyst preparation methods, incineration durations and temperatures, and the addition of Co and Ce on NO-reduction efficiency and selectivity (N2O formation) during the preparation of MnOx/Ti-based catalysts were studied by micropore-size analysis (XRD, XPS, SEM, and FTIR), while considering changeable parameters. Meanwhile, the performance of low-temperature SCR of NO with NH3 over the designed catalysts was tested under various gas hourly space velocities (GHSVs), NH3/NO molar ratios, and contents of NO, NH3, O-2, H2O, and SO2 in a lab-scale reactor. Overall, the Mn(0.3)Ce(0.1)/Ti catalyst, which had high NO-reduction efficiency and selectivity (low N2O formation), was recommended, with the following preparation methods: ultrasonic impregnation;manganese acetate precursor;and incineration at 500 degrees C. Appropriate textural properties (high surface area and small pore and crystallite sizes), well-dispersed amorphous manganese (rather than crystalline) on the anatase surface (rather than rutile), abundant active sites, and long residence time are essential for high NO-reduction efficiency. In practice, NO-reduction efficiency decreased with increasing GHSV and the NH3 and NO contents;however, it initially increased and then became saturated with an increasing NH3/NO molar ratio and O-2 content. Water deactivated the catalyst to a recoverable state, whereas SO2 resulted in unrecoverable deactivation.

关键词： low-temperature SCR MnOx/Ti NO N2O NH3

来源：评论

学校读者我要写书评

暂无评论

LES and URANS study on turbulent flow through 3 x 3 rod bundle with spacer grid and mixing vanes using spectral element method

引用

ANNALS OF NUCLEAR ENERGY 2021年 161卷 108474-108474页

作者： Ju, Haoran Yu, Hao Wang, Mingjun Zhao, Minfu Tian, Wenxi Liu, Tiancai Su, G. H. Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China China Inst Atom Energy POB 275-59 Beijing 102413 Peoples R China Royal Inst Technol KTH Div Nucl Power Safety Roslagstullsbacken 21 S-10691 Stockholm Sweden

In this paper, the turbulent flow in rod bundles with spacer grid and mixing vanes in nuclear reactor core was studied using spectral element method with large eddy simulation (LES) and unsteady RANS (URANS) method. Combining with the radial periodical boundary conditions, the turbulent mixing phenomena in central subchannels were investigated, especially focusing on the flow field after the spacer grid and mixing vanes. Other than setting up long bare rod bundle to establish the fully developed turbulent flow, only a 2-cm-long bare rod bundle was extruded upstream the spacer grid and mixing vanes, while the fully developed laminar velocity profile was applied on the inlet surface for velocity boundary settings. The results indicate that both of the models could predict time-averaged velocity at 0.5Dh, 1Dh, 4Dh downstream mixing vanes properly, while the URANS model underestimate the root-mean-square (RMS) value of fluctuating velocity due to the inlet treatment effect. Furthermore, turbulent kinetic energy contour with transverse velocity vector was combined to investigate the behaviors of vortices formed by split-type mixing vanes, revealing the behavior of vortices for preliminary dynamic and mechanic analysis in design process of fuel assembly. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Turbulent mixing LES URANS Spectral element method CFD validation

来源：评论

学校读者我要写书评

暂无评论

Revealing the unexpected promotion effect of diverse potassium precursors on α-MnO2 for the catalytic destruction of toluene

引用

CATALYSIS SCIENCE & TECHNOLOGY 2020年第7期10卷 2100-2110页

作者： Zhu, Qing Jiang, Zeyu Ma, Mudi He, Chi Yu, Yanke Liu, Xiaohe Albilali, Reem 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 Univ Chinese Acad Sci Natl Engn Lab VOCs Pollut Control Mat & Technol Beijing 101408 Peoples R China Columbia Univ Dept Chem Engn New York NY 10027 USA Imam Abdulrahman Bin Faisal Univ Dept Chem Coll Sci POB 1982 Dammam 31441 Saudi Arabia

The alkali metal potassium has the functions of structure promotion and electronic modulation in metal oxides. Herein, diverse potassium precursors (KOH, KNO3, K2SO4, and KCl) were introduced to alpha-MnO2 nanorods through a facile post-processing strategy. The presence of potassium species has a remarkable promotion effect on the catalytic performance of alpha-MnO2. Amongst them, the KOH/MnO2 sample has the highest activity and can destroy 90% toluene (1000 ppm) at just 226 degrees C with a reaction rate of 3.39 x 10(-4) mol g(cat)(-1) s(-1), which is over 20 times higher than that of pure alpha-MnO2. Different anions in the potassium precursors bring a distinct mutation in the alpha-MnO2 structure, promote the formation of MnO6-K-MnO6 bridging bonds in alpha-MnO2, and exhibit obvious diverse abilities for balancing charge transfer. KOH is identified as the most promising precursor for alkali metal modification, which significantly improves the distribution of K species over the alpha-MnO2 surface and strengthens the content and activity of lattice oxygen. It is confirmed that the lattice oxygen plays a key role in the catalytic oxidation of toluene over alpha-MnO2, which follows the Mars-van Krevelen mechanism. Positive hole defects (Mn3+) caused by KOH treatment play an important role in the diffusion of O and enhance the reducibility of manganese oxide. In addition, the enhanced specific surface area, pore volume, and surface acidity are also conducive for the catalytic oxidation of toluene.

关键词： Nanorods

来源：评论

学校读者我要写书评

暂无评论

A best-estimated correlation for prediction of nucleation radius in sodium boiling

引用

NUCLEAR engineering AND DESIGN 2019年第Apr.期345卷 40-46页

作者： Ma, Zaiyong Qiu, Suizheng Zhang, Luteng Bu, Shanshan Sun, Wan Pan, Liangming Chongqing Univ Minist Educ Key Lab Low grade Energy Utilizat Technol & Syst Chongqing 400044 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

For the safety analysis of sodium-cooled fast reactor, nucleation superheat is a key parameter impacting the boiling process. For liquid metal sodium, models of conventional fluids do not apply and although much research has been performed, the basic mechanism has not been fully revealed. In this paper, by considering the effect of oxide layer and gas-liquid interface behavior in a conical cavity, the deactivation process and nucleation process were analyzed and a best-estimated correlation for nucleation radius was proposed. Taking the inert gas effect into account, the correlation was then used to predict the existing experiment data and good agreement was obtained. The results showed that there may be two types of nucleation due to the wetting property discrepancy, i.e. direct nucleation and the nucleation after interface movement, and the latter may be an explanation of the phenomenon of some data that the nucleation radius can be larger than the deactivation radius. It is also found that the ratio of deactivation radius and nucleation radius would vary with operation conditions and systems, and thus correlations should be employed rather than a constant value.

关键词： Sodium-cooled fast reactor Nucleation Liquid metal Oxide layer Wetting property

来源：评论

学校读者我要写书评

暂无评论

Thermodynamic and economic analyses of a parabolic trough concentrating solar power plant under off-design conditions

引用

APPLIED THERMAL engineering 2019年第0期156卷 340-350页

作者： Wang, Anming Han, Xiaoqu Liu, Ming Yan, Junjie Liu, Jiping Xi An Jiao Tong Univ MOE Key Lab Thermal Fluid Sci & Engn Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

As concentrating solar power technologies progressively move to maturity, large-scale concentrating solar pow plants have elicited increasing attention. The thermodynamic simulation and economic analyses of a 50 M' parabolic trough concentrating solar power plant in northwest China were conducted in the present work. TI effects of meteorological conditions, including direct normal irradiance and ambient temperature, on the 01 design performances were investigated by simulation calculations. Furthermore, economic and sensitive an lyses were conducted based on the annual simulation. Results show that the back-pressure of air-cooled co denser fluctuated with both ambient temperature and power generation. The power generation of summer at autumn days would decrease by 0.53-1.38 MW for the rise of condenser back-pressure. The clouds mainly fected the molten salt level of hot tank in thermal energy storage. In the economic analysis, with the decrease the feed-in tariff from 16.6 C/kWh to 8.6 C/kWh, the maximum total net income dropped from 6.65 M$ 2.43 MS. The optimal design condenser back-pressure rose from 5.0 kPa to 5.5 kPa. Moreover, the optimal desil back-pressure of air-cooled condenser was not sensitive to the cloud effect in certain range, but the total n income had a sharp drop from 7.37 M$ to 4.95 M$.

关键词： Parabolic trough concentrating solar power Off-design conditions Thermodynamic and economic analyses Cloud effect

来源：评论

学校读者我要写书评

暂无评论

Interfacial Charge Modulation via in situ Fabrication of 3D Conductive Platform with MOF Nanoparticles for Photocatalytic Reduction of CO2

引用

CHEMISTRY-A EUROPEAN JOURNAL 2022年第36期28卷 e202200583-e202200583页

作者： Wang, Xiaojun Liu, Yunpeng Chai, Guodong Yang, Guorui Wang, Caiyun Yan, Wei Xi An Jiao Tong Univ Dept Environm Sci & Engn Xian Key Lab Solid Waste Recycling & Resource Rec State Key Lab Multiphase Flow Power Engn Xianning West Rd 28 Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Chem Xianning West Rd 28 Xian 710049 Shaanxi Peoples R China Xian Univ Technol Shaanxi Key Lab Water Resources & Environm Xian 710048 Shaanxi Peoples R China Univ Wollongong ARC Ctr Excellence Electromat Sci Intelligent Polymer Res Inst AIIM Facil Wollongong NSW 2522 Australia

Highly-efficient photocatalytic conversion of CO2 into valuable carbon-contained chemicals possesses a tremendous potential in solving the energy crisis and global warming problem. However, the inadequate separation of photogenerated electron-hole pairs and the unsatisfied capture of CO2 stay the chief roadblocks. Herein, we designed a novel photocatalyst for CO2 reduction by assembling three-dimensional graphene (3D GR) with a typical metal-organic framework material UIO-66-NH2, aiming to construct a built-in electric field for charge separation as well as taking advantage of the typical 3D structure of GR for maximizing the exposed absorption site on the surface. The performance evaluation demonstrated that the photocatalytic activity has been improved for the composite materials compared with that of the pure UIO-66-NH2. Further mechanism investigations proved that the enhanced photocatalytic performance is attributed to the synergy of enhanced CO2 absorption and inhibited photogenerated charge recombination, which could be owing to the better distribution and exposure of absorption and reaction sites on composites, and the redistribution of photogenerated carriers between 3D GR and UIO-66-NH2. This study provides a promising pathway to probe nanocomposites based on MOFs in environmental improvement and other relevant fields.

关键词： CO2 reduction HCOOH photocatalysis three-dimensional graphene UIO-66-NH2

来源：评论

学校读者我要写书评

暂无评论

Experimental research on fragmentation characteristics of molten stainless steel discharged into sodium pool and comparison with molten copper

引用

PROGRESS IN NUCLEAR ENERGY 2020年 118卷 103069-000页

作者： Hu, Liang Ge, Kui Zhang, Yapei Zhang, Dalin Su, G. H. Tian, Wenxi Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Shaanxi Key Lab Adv Nucl Energy & Technol Xian 710049 Shaanxi Peoples R China

Molten Fuel-Coolant Interaction (MFCI) is especially focused in Sodium-cooled Fast Reactor (SFR) with the consideration of possible recriticality and predominant effect on resultant consequences. As the nuclear fuel cladding material of SFR, kilogram quantities of molten stainless steel jet are used in the present experiments to study the fragmentation behavior when discharged into sodium pool. During the interaction between molten stainless steel jet and liquid sodium, the great differences in temperature, velocity and thermophysical properties result in violent sodium boiling, hydrodynamic instability and viscous shearing at the contact interface. The molten stainless steel jet suffers from significant fragmentation under multiple interfacial forces, which increases contact interface area to enhance heat transfer. However, the accelerated solidification of molten stainless steel jet at the contact interface greatly raises the criteria of fragmentation, conversely decreasing the heat transfer. In the present study, the sodium pool depth is varied to study the effect of the dropping height of molten stainless steel and inventory of liquid sodium on the fragmentation characteristics. The temperature variations in sodium pool are measured to estimate energy release during molten stainless steel-liquid sodium interaction. The resultant stainless steel debris is recorded and measured against debris mass with respect to size intervals for morphology analysis and size distribution. Furthermore, experiments with kilogram quantities of molten copper jet are conducted in the present study. The results with molten stainless steel jet are compared to those with molten copper jet and those with molten stainless steel droplets to distinguish fragmentation characteristics. According to the present findings, adequate fragmentation of molten material can be caused by increased relative velocity, high superheat and considerable energy release capability, enhancing heat transfer and

关键词： SFR MFCI Fragmentation Thermal-hydraulic Energy release Size distribution

来源：评论

学校读者我要写书评

暂无评论

Synthesis of amphiphilic Janus SiO2/styrene butyl acrylate polymer microspheres and their application in oil recovery

引用

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND engineering ASPECTS 2023年第1期675卷

作者： Li, Xinru Gao, Dangge Liu, Maochang Zheng, Lijun Li, Pengyu Lyu, Bin Xian Shiyou Univ Coll New Energy Xian 710065 Shaanxi Peoples R China Shaanxi Univ Sci & Technol Natl Demonstrat Ctr Expt Light Chem Engn Educ Xian 710021 Shaanxi Peoples R China Shaanxi Univ Sci & Technol Xian Key Lab Green Chem & Funct Mat Xian 710021 Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China PetroChina Changqing Oilfield Co Oil Gas Technol Res Inst Xian 710021 Shaanxi Peoples R China

We report the design and synthesis of two kinds of amphiphilic Janus SiO2 nanoparticles, including polyacrylic acid/polystyrene (PAA/PS) Janus SiO2 and polyacrylic acid/polymethylmethacrylate (PAA/PMMA) Janus SiO2. The amphiphilic Janus SiO2 nanoparticles can effectively stabilize polystyrene butyl acrylate (P(St-BA)) composite microspheres, forming low-cost oil displacing systems to improve the oil recovery of heterogeneous and low-permeability reservoirs. Among them, the PAA/PS Janus SiO2 stabilized P(St-BA) are demonstrated with good injection, migration, and plugging performance, as well as high temperature and salt resistance. These advantages enable the system an oil recovery increment of 32%. In addition, the microspheres also present good enhanced oil recovery potential in heterogeneous reservoirs, especially for cores with a permeability ratio of 2.0. In principle, the oil displacement of this system is achieved by the synergic effect of amphiphilic Janus SiO2 nanoparticles and composite microspheres. This work thus provides a promising method for high-performance yet low-cost oil recovery improvement.

关键词： Amphiphilic Janus SiO 2 Polymerization Composite microspheres EOR Oil displacement

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

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

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：