检索结果-内蒙古大学图书馆

Experimental Study on flow Patterns in Narrow Rectangular Channels

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Lv, Xindi Zhang, Dalin Song, Gongle Su, Guanghui Tian, Wenxi Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

Plate fuel elements are commonly used in compact nuclear reactors due to the advantages of high fuel consumption. In this paper, the two-phase flow pattern in the coolant channel of plate fuel elements, i.e. the rectangular narrow channel was studied. Visualization flow pattern experiments of upward steam-water two-phase flow in narrow rectangular channels, 745mm long and 67mm wide with gap widths of 1.3mm and 1.9mm, were investigated. The experiments were performed in the conditions of pressure ranging from 1 to 2MPa, mass flow rate ranging from 200 to 1500kg/(m2 ⋅s), inlet subcooling ranging from 20~100°C and tilt angle ranging from 0~ 45°. Three flow patterns, consisting of bubble flow, churn flow and annular flow, were obtained in a wide range of thermal parameters. flow patterns maps were plotted and the influences of pressure, mass flow rate, inlet subcooling, channel gap and tilt angle on the flow pattern transformation of narrow rectangular channel were studied. This study is of great significance for investigating the subsequent heat transfer process of two-phase flow in compact nuclear reactors. © 2022, The Authors. All rights reserved.

关键词： Two phase flow

Thermionic Conversion Performance Analysis of the Single-Cell Thermionic Fuel Element Based on Froba-Thermion Code

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Lu, Kailin Yao, Hao He, Yanan Wu, Yingwei Zhang, Jing Liao, Haoyu Su, Guanghui H. Qiu, Suizheng School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

The thermionic conversion performance of the single-cell thermionic fuel element (TFE) is influenced by fuel mass transfer and other parameters. With the consideration of current flow and heat transfer, the thermionic conversion model and the modified heat transfer model were implemented in FROBA-THERMION. Afterward, both implemented models were verified by comparing with experiments or KATET calculation results. Further, a steady-state performance simulation of the single-cell TFE was carried out. The results indicate that the thermionic conversion efficiency will be decreased due to the emitter temperature flattening caused by fuel mass transfer. In addition, the influence of several key parameters on thermionic conversion efficiency and measures to improve the thermionic conversion efficiency were analyzed. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

Stability and Emission Characteristics of Ammonia/Air Premixed Swirling Flames with Rotating Gliding Arc Discharge Plasma

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Ju, Rongyuan Wang, Jinhua Zhang, Meng Mu, Haibao Zhang, Guanjun Yu, Jinlu Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi’an Jiaotong University Xi’an710049 China School of Aeronautics Engineering Air Force Engineering University Xi’an710038 China

Ammonia received increased attention as a carbon-free fuel and hydrogen carrier. Poor combustion stability and high NOx emission are the main issue for ammonia combustion. Effects of rotating gliding arc (RGA) discharge plasma on the flame stability and NOx emission of NH3/air premixed swirling flames were investigated. The discharge characteristics of the RGA were studied. The flame stabilization mechanisms by plasma were revealed and analyzed according to the flame structure transition and the distribution of key intermediate OH radicals. The NOx emissions were measured by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Results showed that the RGA discharge plasma can enhance the stability and extend the lean blow-off (LBO) limits from 0.6 to approximately 0.43-0.57. A hysteresis phenomenon about the transition between the lift-off flame and the attached flame was observed without plasma and disappeared with plasma activation. The plasma reduces NO and NO2 emissions mainly due to the kinetic and cracking effects of plasma. Extremely low NO emission below 300 ppm can be observed for very lean ammonia flames with an equivalence ratio (f) lower than 0.6, which are stabilized by plasma, while a large amount of unburned NH3 emission is accompanied. © 2022, The Authors. All rights reserved.

关键词： Ammonia

Comparison of Lifetime Performance of Pemfc Stacks with Two Cooling Strategies Under Different Humidity

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lv, Jizu Hu, Chengzhi Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

While reducing the size and Pt loading can achieve a lower proton exchange membrane fuel cell (PEMFC) stack cost, it is also very important to focus on the performance changes of the PEMFC stack during the long-term operation. A 3D PtCo catalysts long-term performance model is established in this study, and PEMFC stacks with one cooling unit per cell (1-cell stack) and three cells (3-cell stack) are employed as the computational domains, respectively. The effective area of each cell is 50 cm2, and the changes in current density as well as effective catalytic area of PEMFC stacks with two cooling strategies before and after long-term operation under different humidity conditions are investigated at low Pt loadings. The results show that there are large differences in the output voltage and current density distributions between the three cells due to the poor membrane hydration affected by the non-uniform temperature distribution, although the 3-cell stack can significantly reduce the size. Localized catalyst degradation in both 3-cell and 1-cell stacks is closely related to the geometry of the cathodic flow field, and non-uniform catalyst degradation is found to increase the activation and mass transfer losses and change the distribution of current density within the membrane. In addition, the 3-cell stack is found to perform even better in terms of durability, especially under high humidity conditions, which provides a potential solution to improve the durability of PEMFC stacks operating in harsh conditions. © 2024, The Authors. All rights reserved.

关键词： Durability

Solar-Wind Energy Complementary Coupling Realizes Magnetic-Field Assisted Efficient Photocatalytic Co2 Reduction

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Kong, Biao Ren, Yuqi Liu, Maochang Zhou, Jiancheng Wang, Ke Wang, Nan Li, Naixu School of Chemistry and Chemical Engineering Southeast University No.2 Dongnandaxue Road Jiangsu Nanjing211189 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Shaanxi Xi'An710049 China

We report the synthesis of a Z-scheme monolithic photocatalyst in the form of copper foam supported TiO2 combining Cu2O and Ag nanoparticles (CF@TiO2/Cu2O-Ag). The designed catalysts with efficient charge separation show superior photocatalytic activity toward CO2 reduction, with a maximum CO yielding rate of 25.58 μmol‧g-1‧h-1. More importantly, we develop a solar-wind energy complementary device, which enables the strong coupling of the magnetic field into the photocatalytic reaction. Specifically, the in-situ space electric field generated from the wind-driven induced electromotive force further enhances the separation and transportation of photogenerated charge carriers in the Z-scheme system. The productivity of CO in the proof-of-concept device based on the use of CF@TiO2/Cu2O-Ag catalyst reaches 71.66 μmol‧g-1‧h-1. This study provides an ideal approach for reinforcing photocatalytic CO2 reduction through muti-field coupling and highlights the prospect of solar-wind energy coupled photocatalysis. © 2023, The Authors. All rights reserved.

关键词： Titanium dioxide

Inverse Analysis of Radiative Properties of Internal Medium and Surface for Cylindrical System Using Csm-Cgm Approach

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Zhang, Chao Li, Ben-Wen Zhou, Rui-Rui Li, Pan-Xin Huang, Ling-Yun Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education School of Energy and Power Engineering Dalian University of Technology Dalian116024 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming650093 China

An inverse analysis is conducted to simultaneously estimate the radiative properties in a 2D cylindrical system including the extinction coefficient, scattering albedo, and the wall emissivity from the knowledge of the radiative heat flux over different boundaries. In which the collocation spectral method (CSM) is developed to solve the forward problem, the conjugate gradient method (CGM) is employed to solve the inverse problem, and the complex-variable-differentiation method is used to treat the sensitivity problem, separately. Meanwhile, the effects of measurement errors, initial values, and imaginary values of complex variables on the precision of the inverse analysis are investigated. Results show that the proposed inverse analysis can successfully retrieve the unknown radiative physical properties of 2D cylindrical system. Under the same physical properties, good inversion results can be obtained by using different wall (end walls and side wall) radiative heat fluxes, but the inversion efficiency from sidewall radiative heat flux is higher. Besides, it is found that, the inversion for the scattered participating medium is more efficient than that for the non-scattered participating medium;the true values and iterative convergence values have little effect on the inversion result;the influence of the initial values and the imaginary values of the complex variable on the inversion cannot be ignored. © 2023, The Authors. All rights reserved.

关键词： Conjugate gradient method

Waste Tire-Derived Graphene Modified Carbon as Anodes for Sodium-Ion Batteries

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Zhou, Ziyi Wang, Silang Wen, Bo Xiao, Jiyuan Yang, Guorui Ding, Shujiang School of Chemistry Engineering Research Center of Energy Storage Materials and Devices Ministry of Education "Four Joint Subjects One Union" School Enterprise Joint Research Center for Power Battery Recycling & Circulation Utilization Technology Xi’an Jiaotong University Xi’an710049 China Xi’an Key Laboratory of Solid Waste Recycling and Resource Recovery State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering Xi’an Jiaotong University Xi’an710049 China

The rational disposal of waste tires poses a ubiquitous challenge globally. Pyrolytic carbon black, a solid by-product produced through pyrolysis, has great application prospects. Carbon-based materials are regard as the most potential commercial anode materials for sodium-ion batteries (SIBs) ， which features cheap, environmentally friendly, and low reaction potential. In this study, three-dimensional vertical graphene composite (TCBp@VGSs) was synthesized from waste tires. The graphene with higher defectiveness offers an increased number of active sites for Na+, while the vertically aligned graphene facilitates rapid electron transfer. As a result, the TCBp@VGSs electrode demonstrates the ability to maintain a reversible capacity of 252.7 mA h g-1 after 100 cycles at a current density of 0.2 A g-1. Furthermore, it exhibits a sustained rate performance of 105.4 mA h g-1 at a current density of 5 A g-1. Moreover, even after 1900 cycles at a current density of 1 A g-1, a reversible capacity of 171.5 mA h g-1 is retained, showcasing good stability and a significantly higher capacity compared to TCBp-1100. This study introduces novel approaches for the high-value utilization of solid-phase by-products from waste tires, offering certain economic benefits, and contributes fresh insights into the advancement of SIBs anodes. © 2024, The Authors. All rights reserved.

关键词： Graphene

Xct Images-Based Pore-Scale Numerical Investigation for Heat Transfer Using Copper Foam Filled with Paraffin Phase Change Material

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Liu, Xinyu Zhou, Zhifu Wu, Wei-Tao Wei, Lei Hu, Chengzhi Lyu, Jizu Huang, Heng Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

The principle of phase change heat transfer using copper foam in the paraffin phase change material (PPCM) are not well understood. In this study, based on X-ray computed tomography (XCT), three dimensional (3D) geometric model of copper foam was established, including PPCM domain. We developed a coupled fluid-solid model to explore phase change for heat transfer in the composite phase change material (CPCM) with copper foam and PPCM. The effects of phase change melting behavior, heat transfer characteristics and homogeneity of temperature were considered. Results of numerical simulation demonstrated that the CPCM had completely melted at 669.8 s. Here the melting time decreased by 45%, compared with the pure PPCM at 1218 s. The extensive heat transfer contact area was offered by the copper foam skeleton. Meanwhile, the melting durations of the CPCM ranged from 4368 s, 2236.3 s, 509.4 s, and 284.6 s corresponding to the heat fluxes with 500 W/m2, 1000 W/m2, 5000 W/m2, and 10000 W/m2. The melting process correlated directly with the heat flux, making it adaptable to the operational demands of diverse electronic components. © 2024, The Authors. All rights reserved.

关键词： Heat flux

Nuclear Thermal Coupling Optimization of Baffled Ntp Reactor

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Duan, Zimian Zhang, Jing Han, Zichao Wang, Mingjun Wu, Yingwei He, Yanan Tian, Wenxi Qiu, Siuzheng Su, Guanghui Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Xi’an710049 China Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Nuclear thermal propulsion (NTP) technology has characteristics of high power and high specific impulse. In particular, CERMET fuel reactor has received a lot of research due to its simple form and structure. A general CERMET fuel reactor model is established by using three-dimensional Monte Carlo neutron dynamics program and commercial CFD program Fluent. After nuclear thermal coupling optimization, three partition schemes of baffled reactor were proposed to reduce the temperature difference between the wall and the coolant and lower the relative spike factor in the inner region. A feasible design of redundant control system was then proposed, with a cold clean excess reactivity greater than $3.44 and a minimum dry shutdown reactivity lower than -$5.95, where there was a high control accuracy of 6.7 pcm/mm. The reactor realized safety of the core temperature lower than 3000K under the conditions of total exit temperature of 2650K and thrust of 25000lb. © 2022, The Authors. All rights reserved.

关键词： Cermets