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SSRN 2024年

作者： Lin, Yue Zhang, Dalin Chen, Yutong Zhang, Xisi Deng, Jian Du, Peng Tian, Wenxi Qiu, Suizheng Su, Guanghui Department of Nuclear Science and Technology State Key Lab. of Multiphase Flow in Power Engineering Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University No.28 Xianningxilu Beilinqu Shaanxi Xi’an710049 China Institute of Reactor Engineering Technology China Institute of Atomic Energy Beijing102413 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China

As an important link in the possible occurrence of steam explosions, the interaction between molten materials and coolant is of great significance for safety analysis in severe accidents of nuclear reactors. This study is based on the two-dimensional multiphase and multi-component fluid dynamics code ACENA to model the process of single molten lead bismuth droplet impacting a water tank and obtain the velocity changes of the molten droplet as it moves through the water tank. Furthermore, a sensitivity analysis of relevant factors such as the heat transfer area fraction and drag coefficient of the droplet is carried out. To verify models in ACENA, the computation results are compared to experimental data. It is demonstrated that the overall trend of the velocity curve acquired by the ACENA code during the interaction between a molten lead bismuth droplet and water is consistent with the experimental results. The droplet falling velocity increases with the increase in droplet temperature when the temperature of water is the same, and the droplet falling velocity increases with the increase of water temperature at the same droplet temperature. The simulation results by ACENA code for MFCI are in good agreement with experiments which verifies the accuracy of relevant models in ACENA. It can provide an effective means for safety analysis of nuclear reactors in China. © 2024, The Authors. All rights reserved.

关键词： Drops

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Study on the effect of particle flow state on the stability of LIBS carbon content detection signal 7

Study on the effect of particle flow state on the stability ...

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7th International Conference on power engineering, ICOPE 2019

作者： Pan, Yuqing Hu, Zhengtao Xu, Heng Zhou, Qulan Li, Na Deguchi, Yoshihiro State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Graduate School of Engineering Science Osaka University Japan

Rice husk, a type of biomass fuel, is rich in amorphous silica. Laser-induced breakdown spectroscopy (LIBS) is a fast-responding non-contact detection method which can realize on-line detection of rice ash components. This paper aims to explore the optimum working conditions of LIBS and extend the compatibility of LIBS technology. The paper uses the sample motion state simulation system to simulate ash, so that the particles can be laser-induced breakdown during the vertical drop and horizontal motion, and then the effect of particle flow state on the stability of the LIBS detection signal can be determined. In addition, the paper compares the effects of two laser pulse widths on the stability of LIBS detection signal by using a 1 ns pulse width laser and a 6 ns pulse width laser to improve the detection error. Experimental studies have found that long pulse width laser provides better stability of spectrum, and the relative standard deviation (RSD) of the detection result is smaller than that of short pulse width laser, and the RSD is smaller in the state of horizontally transferring samples, which can obtain the spectral signal with stronger line intensity. Moreover, sample in conveyor, by contrast, leads to more stable signals. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Stability

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Hydrogen Production from Chemical Looping Steam Reforming of Biomass Waste Cooking Oil

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SSRN 2022年

作者： Zeng, Pingchao Dou, Binlin Zhang, Hua Wang, Yadong Wu, Kai Zhao, Longfei Chen, Haisheng Xu, Yujie School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China

For highly efficient transformation and utilization of waste cooking oil, a new method for hydrogen production by indirect and auto-thermal chemical looping steam reforming (CLSR) of waste cooking oil (WCO) was developed in this work. In conventional and direct CLSR using WCO at a temperature of 650 °C, gas production, hydrogen selectivity, and fuel conversion were low due to the insufficient amount of reducing Ni and heating. Thus, the reactor temperature was increased to 750 °C to pyrolyze enough reducing gas to reduce OCs. Although 84% WCO conversion and 88% hydrogen selectivity were obtained, the OCs deactivated at the last 15 minutes due to the high-temperature sintering of the reduced Ni particles. On this basis, a new type of indirect CLSR with high-temperature steam-assisted pyrolysis of WCO in a two-stages fixed-bed reactor with high stability was developed, which fitted WCO feeding and avoided OCs sintering. The experimental results show that about 90% WCO conversion and about 89% hydrogen selectivity were obtained in indirect CLSR, and the highest hydrogen yield and selectivity were obtained under the conditions of upper pyrolysis temperature of 800 ℃ with a lower CLSR temperature of 600 ℃ and S/C=4.12. In addition, the effect of in-situ CO 2 capture on indirect CLSR achieves the feasibility of hydrogen production and minus carbon emissions. The multiple cycles experiments of indirect CLSR obtained about 90% hydrogen selectivity and fuel conversion, close to 0 CH 4 selectivity, and 24%~26% steam conversion. © 2022, The Authors. All rights reserved.

关键词： Hydrogen production

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Experimental Study on flow Patterns in Narrow Rectangular Channels

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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

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Atomic Nickel on Graphitic Carbon Nitride as a Visible Light-Driven Hydrogen Production Photocatalyst Studied by X-ray Spectromicroscopy

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ACS Sustainable Chemistry and engineering 2023年第14期11卷 5390-5399页

作者： Huang, Yu-Cheng Li, Yanrui Arul, K. Thanigai Ohigashi, Takuji Nga, Ta Thi Thuy Lu, Ying-Rui Chen, Chi-Liang Chen, Jeng-Lung Shen, Shaohua Pong, Way-Faung Dong, Chung-Li Chou, Wu-Ching Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Research Center for X-ray Science & Department of Physics Tamkang University New Taipei City25137 Taiwan International Research Center for Renewable Energy State Key laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukabu305-0801 Japan UVSOR Synchrotron Facility Institute for Molecular Science Okazaki444-8585 Japan National Synchrotron Radiation Research Center Hsinchu30010 Taiwan

The photocatalytic production of solar hydrogen through water splitting by graphitic carbon nitride (g-C3N4) has gained substantial interest due to its advantageous characteristics, such as eco-friendliness, wealth on the earth, favorable bandgap, and easy preparation. Nevertheless, the performance for photocatalytic overall water splitting has been significantly restricted owing to the rapid recombination of charge carriers and slow catalytic kinetics. This investigation demonstrates the utilization of a single-atom Ni-terminating agent to coordinate with the heptazine moieties of g-C3N4, resulting in the formation of a new electronic orbital. g-C3N4 with single-atom Ni-termination can achieve highly efficient photocatalytic overall water splitting into H2 and H2O2 upon visible light irradiation, without requiring the use of any additional cocatalysts. The underlying cause of the enhanced photocatalytic performance of single-atom Ni-incorporated g-C3N4 in hydrogen evolution reaction is identified using synchrotron X-ray spectroscopy and microscopy. The X-ray spectro-microscopic results discover that the new hybrid orbital that is critical for optimizing photocatalysis is associated with carbon defects. The atomic and electronic structures and the band gap of g-C3N4 are adjusted by the new hybrid orbital. Moreover, it synergistically enhances visible light absorption, thereby promoting the separation and transfer of photogenerated charge carriers. The single-atom Ni and the adjacent C atom are recognized as the active sites for water oxidation and reduction, respectively, supporting the efficient photocatalytic splitting of water via a two-electron transfer pathway. This study demonstrated a promising material design for promoting photocatalytic activity in solar energy conversion applications. © 2023 American Chemical Society

关键词： Electronic structure

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

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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

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Research of Cooling Tower Filler Based on Radial Basic Function Artificial Neural Network (Rbf Ann)

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SSRN 2022年

作者： Chen, Jie Zhang, Lixin Zhao, Shunan Chen, Yongbao Song, Huijuan Liu, Jingnan 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 China Institute of Water Resources and Hydropower Beijing100038 China

The filler is the core component of a cooling tower for heat dissipation. The empirical formulas of N, β xv , and ΔP are constitute the performance of filler. In certain conditions, the formulas are obtained by experiments. Performance equations for identical countercurrent fillers are different at varying heights or seawater concentrations. The conventional method is linear interpolation to obtain the filler performance under different conditions. But its uncertainty limits the application of the performance equation to some extent. Therefore, the RBF ANN is adopted to analyze the filler performance based on the existing performance equations in this paper. The dataset is generated by the filler performance equations. The results show that RBF ANN has a preferable prediction effect of filler performance with high correlation (R>0.99) and prediction accuracy (N 10 >90%). In addition, the trend of the predicted results and the experimental results of the filler performance is consistent. Therefore, RBF ANN can accurately predict the filler performance at different heights and different seawater concentrations, which provides the basis for the design of cooling towers. © 2022, The Authors. All rights reserved.

关键词： Cooling towers

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Hydrothermal Hydrolysis Modeling of Lignocellulosic Biomass Using Subcritical Water for Test Packed Bed Reactor

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SSRN 2023年

作者： Wu, Zhonggang Wang, Jiawei Du, Xiaocheng Su, Hanguang China Nuclear Power Operations Co. Ltd. Shenzhen518116 China Department of Mathematics Physics and Electrical Engineering Northumbria University NewcastleNE1 8ST United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xi'An China School of Information Science and Engineering Northeastern University Shenyang China

In this paper, the subcritical water hydrothermal conversion process of lignocellulosic biomass as porous media in packed bed reactor was investigated by numerical simulation. The computational fluid dynamics mathematical modeling was used to describe the transient multi-physical fields formed during the instantaneous formation process of organic functional groups on the bases of experiment. The effect of inlet hydrothermal fluid velocity and temperature on the transient seepage flow, heat and transfer, and organic conversion reaction were investigated by ANSYS FLUENT® software. The results of the simulation indicate that the osmotic pressure and velocity increase with the hydrothermal fluid velocity and temperature. The surface heat transfer coefficient increases with the hydrothermal fluid velocity and temperature, and may reach the maximum within the scope of this paper. Both experimental and numerical simulation results consistently show that within the first 60 minutes of the hydrothermal reaction, the organic reaction rate is mainly determined by the combined model of turbulent-hydrothermal reaction. For a later time period after 60 minutes, the organic reaction rate mainly depends on the single model of hydrothermal reaction. Comparing the same experimental conditions and their real-time measurements, the numerical results in this paper accord with them. © 2023, The Authors. All rights reserved.

关键词： Porous materials

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Simultaneous Analysis of Liquid Film Instabilities and Properties of Swirl Sprays by Telecentric Shadowgraphy

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SSRN 2023年

作者： Machado, Danilo Almeida Costa, Fernando S. Dias, Gabriel Silva Mota, Fábio A.S. Combustion and Propulsion Laboratory National Institute for Space Research SP Cachoeira Paulista12630-000 Brazil State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Shanxi Xi’an710049 China

A telecentric shadowgraphy optical system was utilized to determine macroscopic and microscopic parameters of sprays and the measurement of conical liquid films formed by dual pressure swirl injectors. Spray cone angles, breakup lengths, mean droplet velocities, momentum flows, wave amplitude ratios and maximum wave growth rates were simultaneously measured using high-speed images with kHz frequencies. Two injectors were tested with inner nozzles having Abramovich geometric constants Kint = 2 and 2.125 and external nozzles with geometric constants Kext = 2.9 and 1.9792, respectively. Injection pressures were varied from 0.05 to 0.5 MPa and water was used as test fluid. The experimental data indicate that the breakup length, droplet velocity, flow momentum and disturbance amplitude ratio are higher for injectors with larger mass flow rates, for a given injection pressure. The maximum amplitude ratios of the conical liquid film disturbances varied in the range 2.32 © 2023, The Authors. All rights reserved.

关键词： Liquid films

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Simultaneous Analysis of Liquid Film Instabilities and Properties of Swirl Sprays by Telecentric Shadowgraphy

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SSRN 2023年

作者： Machado, Danilo Almeida Costa, Fernando S. Dias, Gabriel Silva Mota, Fábio A.S. Combustion and Propulsion Laboratory National Space Research Institute SP Cachoeira Paulista12630-000 Brazil State Key Laboratory of Multiphase Flows in Power Engineering Xi’an Jiaotong University Shanxi Xi’an710049 China

A telecentric shadowgraphy optical system was utilized to determine macroscopic and microscopic parameters of sprays and the measurement of conical liquid films formed by dual pressure swirl injectors. Spray cone angles, breakup lengths, mean droplet velocities, momentum flows, wave amplitude ratios and maximum wave growth rates were simultaneously measured using high-speed images with kHz frequencies. Two injectors were tested with inner nozzles having Abramovich geometric constants Kint = 2 and 2.125 and external nozzles with geometric constants Kext = 2.9 and 1.9792, respectively. Injection pressures were varied from 0.05 to 0.5 MPa and water was used as test fluid. The experimental data indicate that the breakup length, droplet velocity, flow momentum and disturbance amplitude ratio are higher for injectors with larger mass flow rates, for a given injection pressure. On the other hand, the maximum wave growth rate of the liquid film is higher for injectors with smaller mass flow rates. The maximum amplitude ratios of the conical liquid film disturbances varied in the range 2.32 © 2023, The Authors. All rights reserved.

关键词： Liquid films

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