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The Interaction and Activation of Fe2o3/Ceo2 Oxygen Carrier in Chemical Looping Dry Reforming of Methane

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SSRN 2024年

作者： Zhang, Jinrui Liu, Xiaozhi Pan, Yue Wang, Yuhan Yang, Tianlong Li, Peng Shen, Yuanhui Su, Dong Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 710049 China

Chemical looping dry reforming of methane (CL-DRM) holds great promise for both CO2 utilization and syngas production with high efficiencies. The structure and component of oxygen carriers (OCs) are critical factors that influence the CL-DRM performances, such as reaction activity and production selectivity. Incorporating CeO2 is known to enhance the reactivity and stability of Fe2O3 for chemical looping reforming. However, the underlying mechanism of how CeO2 synergistically interact with Fe2O3 to enhance performances is still not clear. In this work, we comparatively investigate CeO2 supported Fe2O3 OCs in interfacial and physical Fe-Ce contact modes. The OC with sol-gel method achieves 80% CH4 conversion and 96% CO selectivity, significantly improved from OC with the mechanically mixed sample. Additionally, we found a strong interaction between Fe2O3 and CeO2 components, resulting in the formation of CeFeO3 after the first cycle. Our in-situ environmental transmission electron microscopy study shows that the Fe2O3-CeO2 interaction promotes the oxygen release during the reduction. Iron exhibited significant activity with ceria under CO2, dissolving into CeO2 lattice and forming CeFeO3. Density function theory results suggest that the improved reactivity of Fe2O3/CeO2 OC results from the enhanced oxygen ion migration in CeFeO3 © 2024, The Authors. All rights reserved.

关键词： Sol-gels

Design and Optimal Thermal Efficiency Contrastive Analysis on Closed Brayton Cycle Systems with Different Fluids of Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Liu, Xiuting 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 CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor, the closed Brayton cycle system was selected as the energy conversion system, and the thermodynamic analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed. The results of the thermodynamic analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest and reaching 46.6% with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The results of the exergy analysis show the CO2 cycle has the highest potential to improve thermal efficiency, which has the highest improvement from 43.48% to 49.31% with the recompression process. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

Dye visualization of the wake of a near-wall particle in response to a periodic oscillation

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Measurement: Sensors 2021年 13卷

作者： Li, Xing Zhang, Haibin Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'anShaanxi710049 China

In turbulent dispersed multiphase flows, the interaction between the particle wake and the ambient turbulent fluctuation can be crucial for the change of the multiphase system. This issue is extremely complex due to the chaotic nature of the turbulence. In this paper, the ambient turbulent fluctuation of certain frequency is simulated by the Karman vortex street behind a horizontally placed cylinder, and the response of the wake of a stationary near-wall particle to the oncoming oscillation is investigated. The dye visualization is used to mark the vortex structures of the wake and the oncoming oscillation, respectively, and power spectrum analysis is conducted to reveal the features in the frequency domain. Results show that at relatively low Rep, the oncoming oscillation has little effect on the wake. As Rep increases, the response of the wake to the oncoming oscillation is evident. High-frequency fluctuation dissipates very fast and only exists near the particle. On the contrary, the life span of the low-frequency fluctuation lasts for a much longer period and exists far downstream. In addition, the self-induced vortex shedding is not notable and is overwhelmed by the oncoming oscillation. © 2020 The Author(s)

关键词： Wakes

Novel Solid-state Hydrolysis Kinetics of Nabh4 for Stable and High-Capacity On-Line Hydrogen Production

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SSRN 2024年

作者： Chen, Jiawei Wu, Zhen Zheng, Jie Shi, Yu Xie, Lei Yang, Fusheng Wang, Yuqi Zhang, Zaoxiao School of Chemical Engineering Northwest University Xi’an710069 China School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China College of Chemistry and Molecular Engineering Peking University Beijing100871 China Sunan Institute for Molecular Engineering Peking University Jiangsu 215500 China State Key Laboratory of Multiphase Flow for Power Engineering Xi’an Jiaotong University Xi’an710049 China

Solid-state hydrolysis of NaBH4 could achieve high-capacity on-line hydrogen production. However, the stability of hydrogen production in the solid-state hydrolysis process has been questioned. In this paper, a novel kinetics is proposed for the solid-state hydrolysis behavior. The acceleration factor β is introduced into the traditional shrinking core model to reveal the relationship between "dissolution" and "catalytic hydrolysis" in the solid-state hydrolysis process. The comparison results show a good agreement between the model and experiment in the temperature range of 303.15-348.15 K. Meanwhile, the kinetics conclusions and product characterization indicated that the "excessive dissolution" of NaBH4 and the "dehydration of by-products" are two important factors contributing to the uncontrolled reaction. Based on the parametric analysis and experimental verification, the optimum temperature for solid-state hydrolysis is approximately 323.15 K. Besides, the adjustment of the water intake strategy to intermittent intake reduced water consumption by 36.6%. As a result, the hydrogen release capacity could be increased to as high as 5.49 wt.% (close to the U.S. Department of Energy 2025 gravimetric hydrogen storage capacity of 5.5 wt.%), even though the weight of water is taken into account as reactant. © 2024, The Authors. All rights reserved.

关键词： Hydrolysis

Design and Optimal Thermal Efficiency Analysis on Closed Brayton Cycle System of Fluoride-Salt-Cooled High-Temperature Advanced Reactor (Fustar)

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Yun, Shichang Zhou, Xingguang Jiang, Dianqiang Lv, Xindi Feng, Zhenyu Wu, Wenqiang Tian, Wenxi Qiu, Suizheng Su, G.H. Zhao, Quanbin Liu, Xiuting 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 CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China

To match the advantages of Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR): the high temperature, inherent safety, compact structure, and modularization, the closed Brayton cycle system was selected as the energy conversion system, and the enthalpy analysis, conjugate gradient optimization, and exergy analysis were performed. The pinch point constraint method based on simultaneous equations was proposed to improve the calculation efficiency and ensure the unity of comparison standards, and the exergy analysis was used to quantify and optimize the exergy losses for the equipment. For the simple regenerative cycle configuration, the thermal efficiency and mass flow rate of the cycle system with various fluids (far-critical fluids: air, nitrogen, helium, and argon, near-critical fluids: carbon dioxide, sulfur hexafluoride, propane, and xenon) were analyzed, at the highest thermal efficiencies. The results of enthalpy analysis show that the thermal efficiency of the sulfur hexafluoride cycle is the highest with the simple regenerative cycle configuration. The thermal efficiency of the far-critical fluid cycle is more sensitive to turbine efficiency. The exergy analysis shows the CO2 cycle has the highest potential to improve thermal efficiency. The method and conclusion of this paper can provide references for the design and optimization of the Brayton power cycle system. © 2022, The Authors. All rights reserved.

关键词： Enthalpy

The Role of Particle-Vortex Interaction in Hydraulic Performance and Erosion Behavior of Semi-Open Centrifugal Pump: Effect of Particle Size

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SSRN 2023年

作者： Wang, Kai Liu, Hanyu Wang, Like Guo, Pengcheng Wang, Yueshe Yang, Junfeng State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi’an University of Technology No.5 Jinhua South Road Xi’an710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China Shaanxi Provincial Dongzhuang Water Conservancy Engineering Co. Ltd Xi’an713200 China

The interaction between the particle migration and vortex evolution aggravates the complexity of erosion on the flow components. In this work, the liquid-solid two-phase flow of semi-open centrifugal pump under different particle sizes is simulated based on the four-way coupling Euler-Lagrange method, in which the fluid-particle interaction and particle-particle interaction are taken into account. The interrelationship among vortex structure, particle migration and surface erosion behavior is revealed. The results show that the erosion area is mainly distributed in the blade leading edge, the pressure surface inlet edge and the hub. When the particle size is 0.1 mm and 0.3 mm, due to the good following characteristic of particles and the inhibition effect on tip leakage vortex, the particles are easy to impact the outlet edge of blade suction surface and the hub, which induce severe erosion. As the particle size decreases, the number of particles flowing into the tip clearance layer increases. Therefore, the frequent impact of particles on the tip leakage vortex leads to the breakup, separation and refusion of the vortex, which aggravates the flow instability. This paper provides a new insight into the hydraulic performance and erosion characteristics of semi-open centrifugal pump in terms of particle-vortex interaction. © 2023, The Authors. All rights reserved.

关键词： Particle size

Boosting photocatalytic hydrogen production by creating isotype heterojunctions and single-atom active sites in highly-crystallized carbon nitride

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Science Bulletin 2022年第5期67卷 520-528,M0004页

作者： Shaohua Shen Jie Chen Yiqing Wang Chung-Li Dong Fanqi Meng Qinghua Zhang Yiliang Huangfu Zhi Lin Yu-Cheng Huang Yanrui Li Mingtao Li Lin Gu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China Department of Physics Tamkang UniversityNew Taipei City 25137TaiwanChina Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity,but is yet to be ***,we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride(CCN)to triazine-based poly(triazine imide)(PTI),rendering the creation of singleatom cobalt coordinated isotype CCN/PTI ***-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88%at 425 nm for photocatalytic hydrogen production with a rate achieving3538μmol h^(-1)g^(-1)(λ>420 nm),which is 4.8 times that of CCN and 27.6 times that of *** high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration,and the single-atom Co sites for accelerating surface oxidation reaction.

关键词： Photocatalytic hydrogen production Single-atom cobalt Crystalline carbon nitride Poly(triazine imide) Isotype heterojunctions

Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

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Plasma Science and Technology 2020年第7期22卷 75-82页

作者： Kai RONG Zhenzhen WANG Ruomu HU Renwei LIU Yoshihiro DEGUCH Junjie YAN Jiping LIU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China Graduate School of Technology Industrial and Social SciencesTokushima UniversityTokushima 770-8501Japan Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi'an Jiaotong UniversityXi'an 710049People’s Republic of China

Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental *** gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg *** experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise *** Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed *** Hg signal intensity and signal to noise ratio decreased with the increase in delay *** to the above results,the optimized measurement conditions can be *** Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method *** relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.

关键词： laser-induced breakdown spectroscopy flue gas trace heavy metal quantitative analysis

ȮH insights into the interaction of hydrogen-rich methane and water: Laser absorption experiments and chemical kinetics

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Combustion and Flame 2025年 278卷

作者： Xin Zhang Zilong Feng Congjie Hong Wuchuan Sun Zuohua Huang Yingjia Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 PR China

Flue gas recirculation and steam injection are employed in hydrogen-rich gas turbines to stabilize fuel reactivity and improve cycle efficiency, introducing high water vapor content into the combustion chamber and thereby necessitating an investigation of water-fuel interactions at elevated temperatures. This study employed UV laser absorption diagnostics behind reflected shock waves to conduct in situ measurements of the ȮH concentration time-histories during the oxidation of CH 4 /H 2 /H 2 O/O 2 /Ar mixtures at pressures of approximately 1.3, 5.0, and 15.2 atm and temperatures ranging from 1225 to 1888 K with varying hydrogen blending and water addition ratios. The absorption lineshapes of the ȮH R 1 (5) transition in the A-X(0,0) vibronic band were characterized after broadening and shifting in Ar at different pressures, with diagnostic center wavelengths set at 306.6868 nm (1.3 atm), 306.6874 nm (5.0 atm), and 306.6886 nm (15.2 atm), respectively. The obtained ȮH concentration time-history data were compared in detail with predictions from eight representative reaction kinetic models, and the predictive capability of the models for ȮH behavior was quantitatively assessed using the error function method. NUIGMech1.1 exhibited superior performance in predicting ȮH behavior and was subsequently selected for kinetic analysis to elucidate stage-specific micro-mechanisms and identify key reactions driving the concentration evolution. The activating effect of H 2 on ȮH behavior during CH 4 oxidation was investigated. Results indicate that higher hydrogen levels intensify hydrogen-related reaction pathways, expanding the radical pools (H, ȮH, and Ö), thereby promoting fuel consumption through Ḣ-atom abstraction reactions. Additionally, by introducing weak collision H 2 O* and inert H 2 O**, the thermodynamic and kinetic effects of water were distinguished. The results show that under the current conditions, H 2 O primarily affects ȮH behavior through direct participatio

关键词： Hydrogen-enriched methane Kinetic models Laser absorption Water addition ȮH time-histories