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Microscopic characteristics study of liquid ammonia spray under different flash boiling conditions

Fuel 2025年 401卷

作者： Liu, Xiao Zeng, Gangwei Yao, Xiaoxin Tang, Chenglong Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Liquid ammonia, as a zero-carbon fuel, has received widespread attention in the field of internal combustion engines. The development of ammonia spray and evaporation models urgently requires accurate particle size distribution data. In this study, microscopic characteristics of liquid ammonia spray were firstly experimentally investigated under conditions of high injection pressure (up to 80 MPa) and ambient pressure (up to 4 MPa) with a single-hole injector (0.3 mm). Statistical results of microscopic parameters, including Sauter Mean Diameter (SMD), characteristic droplet diameter, and droplet number density were obtained over a wide range. The results indicate that ambient pressure or RP significantly affects the microscopic characteristics of ammonia spray. In flare flash boiling region (pressure ratio RP ≤ 0.3), ammonia spray produces more droplets with smaller diameter and the statistical SMD is around 15 μm. The droplet size increases and number density decreases with the increasement of ambient pressure or RP. In the transition flash (0.3 P ≤ 1) and non-flash boiling region (RP > 1), the SMD statistical results are approximately 20 and 24 μm, respectively. Increasing the injection pressure can promote atomization and generate more smaller droplets, with a more uniform distribution. Ambient temperature slightly affects the microscopic characteristics of liquid ammonia spray within the temperature range selected for this study, but evaporation becomes more pronounced as the ambient temperature increases. The wide range droplet size distribution and SMD are believed to provide important data for ammonia spray modeling and simulation. © 2025

关键词： Internal combustion engines

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flow and residence time distribution characteristics in continuous hydrothermal reactor under different heating schemes

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Chemical engineering Science 2025年 316卷

作者： Li, Yi Wang, Junying Li, Xiaoyu Jin, Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi710049 China

Residence time distribution (RTD) is of significance for reflecting materials or intermediate products dispersion and actual reaction time inside continuous hydrothermal reactors of supercritical water gasification technology. Generally, RTD is strictly related to flow field, which can be affected by wall heating schemes. In order to propose methods to regulating RTD, effects of different heating schemes on flow and RTD characteristics are investigated and compared by numerical simulation. The results indicate that increasing heat flux, interrupting boundary flow by interlace heating, and setting cooling walls can significantly regulate RTD. By analyzing the correspondence of flow and RTD, the mechanisms of increasing materials and intermediate products dispersion can be attribute to the increase of flow instability and the generation of additional vortices. For example, in the cases of present work, the narrow-strip double-vortex generated by mixing between thermal boundary flow and branch flow may significantly increase average residence time and materials distribution range from 10.93 s and 1.00 to 22.83 s and 1.51. In the region above branch inlet without time-averaged vortex structure, the increasing of flow instability caused by wall heating is observed to widen materials distribution range from 0.75 to 0.99. Heating scheme customized according to these mechanisms can regulating RTD as expected, proving the feasibility and significance of regulating RTD by heating schemes. © 2025

关键词： Reaction intermediates

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EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD BUNDLE 29

EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD B...

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2022 29th International Conference on Nuclear engineering, ICONE 2022

作者： Liu, Weihua Yuan, Hongsheng Wu, Pan Wang, Ting Shan, Jianqiang School of Nuclear Science and Technology Xi'an Jiaotong University No. 28 Xianning West Road Shaanxi Xi'an China China Nuclear Power Technology Research Institute Co. Ltd No.1001 Shangbu Middle Road Futian District Guangdong Shenzhen518026 China The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780791886410

In the current study, a series of reflood tests with uniformly power input have been carried out at the 5×5 rod bundle film boiling test facility of the Nuclear Safety and Operation laboratory(NUSOL) of Xi'an Jiaotong University and the experimental results have been analyzed in detail. The effect of several parameters, including subcooling of coolant (10K to 75K), coolant flow rate (2.5m/s to 10.0m/s) and input wall linear power density (7 W/cm to 13 W/cm) on quench front of reflooding patterns have been studied. It is observed that the quench front during reflood stage of the rod bundle channel is sensitive to above parameters. Increase in input wall linear power density, and decrease in flow rate and subcooling of coolant results in delayed reflooding. The temperature, heat flux and heat transfer coefficient on the rod surface have been got via the self-development Reflooding Experimental Data Analysis (REDA) code. The data is not only useful for the development of theoretical models for film boiling heat transfer, two-phase void fraction, pressure drop, and rod bundle reflooding prediction, but also can be used as a benchmark data base for evaluating the analysis code of Loss of Coolant Accident (LOCA) in reactor and the design of the residual heat removal system. Copyright © 2022 by ASME.

关键词： Coolants

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Identification of flow cut-off pattern and prediction of cut-off time of gas-liquid two-phase flow in pipeline-riser system

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Physics of Fluids 2025年第5期37卷

作者： Liu, Tianyu Wang, Hanxuan Zou, Suifeng Du, Yaohua Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

For offshore pipeline-riser systems, cyclic flow cut-off in slugging flow pattern should be identified and necessarily mitigated to satisfy the requirement of normal operation of gas-liquid separator. Since conventional studies on flow pattern identification were not directly related to the harmfulness of slugging and the decision of flow control, this study develops a risk assessment method for offshore riser systems based on the characteristic parameters of riser outlet signals, achieving an identification accuracy exceeding 90% at different valve openings. Notably, the method maintains exceptional performance under high-pressure conditions, with identification accuracy reaching 96.74% at 10 MPa. On the other hand, this study focuses on the prediction of cut-off duration time in a cycle instead of the cycle period. We establish a predictive model for flow cut-off duration time under different choking conditions. Validation across diverse pipeline systems demonstrates strong reliability of the model, exhibiting maximum prediction errors of 30%. The model's coefficients can be fitted by a small dataset without significant loss of accuracy, and the coefficients are conservative, indicating strong applicability in the field operation. These findings offer significant theoretical insights and practical solutions for enhancing the operational safety of offshore oil and gas transportation systems. © 2025 Author(s).

关键词： Marine risers

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Study on the Catalytic Performance of Nano-Mesoporous Cobalt-Based Catalysts for Glycerol Dry Reforming

SSRN

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SSRN 2022年

作者： Dou, Binlin Wang, Yadong Zhang, Hua Wu, Kai Ren, Ruijia 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

Dry reforming is an efficient utilization technology that can convert CO 2 into high-value-added syngas. In this work, nano-mesoporous CeO 2 -supported Co-based catalysts were successfully prepared by the colloidal solution combustion method and used in glycerol dry reforming (GDR) experiments. The characterization results show that the prepared catalyst has a uniform mesoporous structure, and the Co-Fe-Ce catalyst has a higher specific surface area and stronger metal-support interaction than the Co-Ce catalyst. Thermodynamic analysis was conducted using a non-stoichiometric method methodology based on Gibbs free energy minimization. Catalytic experiments were carried out at 650°C to 800°C. The results showed that the Co-Fe-Ce catalyst exhibited higher activity and selectivity in the GDR reaction, and the glycerol conversion of 7CoFeCe at 750 °C reached 84.8%. The 10 h stability experiment shows that the Fe promoter has a positive effect on the stability of the catalyst. The TPO results indicate that Fe doping can suppress filamentous carbon formation. © 2022, The Authors. All rights reserved.

关键词： Catalyst activity

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Heavy Oil Upgrading Using Naoh/Cuso4 Composite Catalyst in Aquathermolysis

SSRN

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SSRN 2022年

作者： Zhou, Yantao Zhao, Qiuyang Miao, Yan Wang, Xuetao Zhang, Yanlong Wang, Yechun Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xinjin Weihua Institute of Clean Energy Research Foshan528216 China

To obtain an inexpensive and efficient catalyst in the in-situ upgrading of heavy oil, the NaOH/CuSO4 composite catalyst was proposed in this work. Firstly, the experiments found the viscosity of heavy oil increased with addition of CuSO4 under 300°C in aquathermolysis. Then, the addition of NaOH was found to improve the catalyst capacity of CuSO4 significantly. The NaOH/CuSO4 decreased the viscosity by 81.43% under 300°C. The further analysis revealed the Cu atoms of CuSO4 enter into the heavy oil molecules to increase viscosity, and the NaOH inhabits the viscosity increasing reaction. Besides, the Cu and CuOx with a higher catalytic capacity produced with the addition of NaOH. These conclusions are helpful to understand the aquathermolysis upgrading mechanism and develop a type of inexpensive and efficient composite catalyst. © 2022, The Authors. All rights reserved.

关键词： Sulfur compounds

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High-Entropy (Cocrfemnni)3o4 Catalysts for Propane Catalytic Destruction: Effect of the Precipitation Agent

SSRN

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SSRN 2023年

作者： Ma, Yue Zhang, Yun Jian, Yanfei Jiang, Zeyu Chai, Shouning Li, Lu Xia, Lianghui He, Chi State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Department of Physics and Information Technology Baoji University of Arts and Sciences Shaanxi Baoji721016 China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing101408 China

Efficient catalytic destruction of light alkane with ultra-stable and highly symmetric structure is still an intractable issue. High entropy oxides (HEOs) with high chemical disorder and lattice distortion and superior stability have shown great potential in heterogeneous thermocatalysis. Herein, spinel-type HEOs are synthesized via a scalable co-precipitation method with different precipitants (NaOH, Na2CO3, and NaHCO3) and firstly adopted in catalytic destruction of propane. Results demonstrate that the HEO-NaOH possesses the best activity, achieving 90% of propane conversion at 325 °C with an apparent activation energy of 56 kJ·mol-1. Compared with other two HEOs, HEO-NaOH system has larger quantities of surface oxygen vacancies and easily forming several reactive oxygen species (OOH-, O2-, and OH-, etc.), which significantly contribute to the catalytic performance. Moreover, the excellent water resistance of HEOs is verified due to their high conformational entropy and structural stability. Reaction mechanism reveals that OOH- and O2- are the key species in the oxidation of C3H8, which break C-H and C-C bonds in sequence, and are then converted to oxygenated compounds via oxygen oxidation before the final mineralization. The present work provides new insights into the fabrication of efficient catalysts for light alkane destruction as well as other thermocatalytic applications. © 2023, The Authors. All rights reserved.

关键词： Sodium hydroxide

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Multi-Objective Optimization Design of a Solar-powered Integrated Multi-Generation System Based On Combined Sco 2 Brayton Cycle and Orc Using Machine Learning Approach

SSRN

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SSRN 2024年

作者： Zhang, Junyi Wang, Jiangfeng Liu, Wenxing Hu, Bin Lou, Juwei Zhao, Pan Institute of Turbomachinery State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Nuclear Power Institute of China No. 328 Section 1 Changshun Avenue Sichuan Chengdu610213 China DongFang Electric Engineering& Consulting Co. Ltd 18 Xixin Avenue High-tech West Zone Sichuan Chengdu611731 China

With the rapid development of technology and the accelerated degradation of the global environment, there is an urgent need to find a clean and efficient energy solution to replace traditional fossil fuels for energy production. Additionally, this solution should also meet the growing demand for various energy products for energy user. In particular for remote areas such as islands, coastal regions and deserts which are far from the power grid, regular resources such as power, freshwater, and cooling are all scarce. Therefore, integrating freshwater and cooling subsystems into the power generation system to create a multi-generation system can facilitate achieving energy self-sufficiency in remote regions. This paper proposes an integrated multi-generation system powered by a solar power tower (SPT) according to the principle of cascading energy utilization, which includes a supercritical CO2 (SCO2) Brayton cycle, an Organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), and a reverse osmosis (RO) unit. A mathematical model is established to analyze the system performance from the perspectives of energy, exergy and economics. Different machine learning algorithms including back propagation neural network (BPNN), support vector regression (SVR), random forest (RF) are used to develop prediction models of the system performance. By comparing and analyzing the predictive performance of different machine learning models, the optimal machine learning model is obtained as a surrogate model for the thermodynamic model of the proposed system to accelerate the optimization process. The results show that the BPNN model demonstrates the highest predictive accuracy and the lowest relative error fluctuation, maintaining a relative error of less than 1% for over 97.5% of the data in the testing set. When comparing the multi-objective optimization results of the BPNN model with those of the thermodynamic model from multiple perspectives, it can be observed that the res

关键词： Neural network models

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

SSRN

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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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Development in the application of laser-induced breakdown spectroscopy in recent years:A review

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Frontiers of physics 2021年第2期16卷 45-69页

作者： Lian-Bo Guo Deng Zhang Lan-Xiang Sun Shun-Chun Yao Lei Zhang Zhen-Zhen Wang Qian-Qian Wang Hong-Bin Ding Yuan Lu Zong-Yu Hou Zhe Wang Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesSheyang 110016China School of Electric Power South China University of TechnologyGuangzhou 510640China State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Laser SpectroscopyShanxi UniversityTaiyuan 030006China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China Key Laboratory of Photonic Information Technology School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China School of Physics Dalian University of TechnologyNo.2 Linggong RoadGanjingzi DistrictDalian 116024China Optics and Optoelectronics Laboratory Ocean University of ChinaQingdao 266100China State Key Lab of Power Systems Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

Laser-induced breakdown spectroscopy(LIBS)has been widely studied due to its unique advantages such as remote sensing,real-time multi-elemental detection and none-to-little *** the efforts of researchers around the world,LIBS has been developed by leaps and ***,in recent years,more and more Chinese LIBS researchers have put tremendous energy in promoting LIBS *** is worth mentioning that the application of LIBS in a specific field has its special application background and technical difficulties,therefore it may develop in different stages.A review summarizing the current development status of LIBS in various fields would be helpful for the development of LIBS technology as well as its applications especially for Chinese LIBS community since most of the researchers in this field work in *** the present work,we summarized the research status and latest progress of main research groups in coal,metallurgy,and water,*** on the current research status,the challenges and opportunities of LIBS were evaluated,and suggestions were made to further promote LIBS applications.

关键词： laser-induced breakdown spectroscopy application

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