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Numerical investigation on characteristics of interfacial wave of liquid film in gas-liquid two-phase flow using OpenFOAM

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Chinese Journal of Aeronautics 2024年第2期37卷 233-248页

作者： Xiaoqi MA Yueshe WANG Jiaming TIAN state Key Laboratory of Multiphase Flow in Power engineering Xi’an Jiaotong UniversityXi’an 710049China

Liquid film cooling as an advanced cooling technology is widely used in space *** operation of liquid film along the rocket combustion inner wall is crucial for thermal protection of rocket *** stability of liquid film is mainly determined by the characteristics of interfacial wave,which is rarely investigated right *** to improve the stability of thin film has become a hot *** view of this,an advanced model based on the conventional Volume of Fluid(VOF)model is adopted to investigate the characteristics of interfacial wave in gas-liquid flow by using OpenFOAM,and the mechanism of formation and development of wave is revealed intuitively through numerical *** effects from gas velocity,surface tension and dynamic viscosity of liquid(three factors)on the wave are studied *** can be found that the gas velocity is critical to the formation and development of wave,and four modes of droplets generation are illustrated in this ***,a gas vortex near the gas-liquid interface can induce formation of wave easily,so changing the gas vortex state can regulate formation and development of ***’s more,the change rules of three factors influencing on the interfacial wave are obtained,and the surface tension has a negative effect on the formation and development of wave only when the surface tension coefficient is above the critical value,whereas the dynamic viscosity has a positive effect in this ***,the maximum height and maximum slope angle of wave will level off as the gas velocity ***,the maximum slope angle of wave is usually no more than 38°,no matter what happens to the three factors.

关键词： Interfacial wave Gas-liquid Two-phase flow VOF model OpenFOAM

Acoustic characterization of hydrate formation and decomposition in clay-bearing sediments

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Petroleum Science 2024年第4期21卷 2830-2838页

作者： Yi-Jian Zhu Xiao-Mei Yang Xing Huang Hao Li Xiao-Hui Wang Yi-Fei Sun Peng Xiao Chang-Yu Sun Guang-Jin Chen state Key Laboratory of Heavy Oil Processing College of Chemical Engineering and Environment China University of Petroleum

Understanding the acoustic characteristics of hydrates in various sediments is crucial for hydrate resource detection and safe and efficient exploitation, as hydrate occurrence patterns vary greatly in different sediments. In this work, sediments with different bentonite contents, water saturations, and types were prepared to investigate the characteristics of P-wave velocity(reflecting the magnitude of hydrate saturation in the sediment) and amplitude(reflecting the degree of hydrate-sediment cementation) during hydrate formation and depressurization. During hydrate formation, the P-wave velocity and amplitude have similar trends. As clay content increases, the P-wave velocity increase rates quickened. On the other hand, the increased rate of P-wave velocity slows down with the increase of water saturation in the clay-bearing sediments. Comparing various types of sediment shows that the water absorption and swelling of bentonite reduce the pore space, speeding up the cementation of the hydrate with the sediment and increasing P-wave velocity at a faster rate. Correspondence between P-wave velocity and hydrate saturation is strongly related to sediment type, clay content, and water *** rapidly decreasing amplitude in the early stage of hydrate depressurization indicates that hydrate in clay-bearing sediments is weakly cemented to the sediments, which is prone to stratigraphic *** findings of this study offer guidance for hydrate resource assessments in clay-bearing sediments as well as geologic risk estimations during hydrate mining.

关键词： gas hydrate bentonite illite P-wave velocity amplitude

Optimizing hemicelluloses pre-extraction in eucalyptus kraft pulping:A pathway towards enhancing pulp mill biorefineries

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Chinese Journal of Chemical engineering 2024年第6期70卷 162-172页

作者： Yuhan Wang Danqi Xue Jingjing Zhuo Zhouyang Xiang state Key Laboratory of Pulp and Paper engineering South China University of TechnologyGuangzhou 510640China

A critical pathway towards enhancing pulp mill biorefineries is to integrate the extraction and utilization of hemicelluloses into the pulping ***,an industrial pre-extraction strategy for hemicelluloses targeting eucalyptus kraft pulping process was *** solution or pulping white liquor was used to pre-extract hemicelluloses before the actual pulping *** response surface methodology(RSM)technique was applied to investigate the most suitable conditions to maximize the yield of these hemicelluloses while simultaneously minimizing the damage to pulp yields and ***(105 to 155℃),alkali concentration(3%to 8%),sulfidity(20%to 30%)and retention time(19 to 221 min)were combined to evaluate their effects on hemicellulose yields and chemical *** optimal pre-extraction conditions identified in this work(5.75%NaOH concentration,25%sulfidity at 135℃for 60 min)successfully allowed recovering 4.8%of hemicelluloses(based on the wood dry mass)and limited damages to pulp yields and *** cellulose content in pulp can even be increased by about 10%.Hemicellulose emulsification properties were also evaluated,which were comparable to synthetic *** study provides an industrial pathway to effectively separate and utilize wood hemicelluloses from the pulping process,which has the potential to improve the economy and material utilization of pulp and paper mills.

关键词： Hemicelluloses Xylan Pre-extraction Kraft pulping Emulsifying Response surface methodology(RSM)

Market Equilibrium Based on Cloud-edge Collaboration

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 96-104页

作者： Tong Cheng Haiwang Zhong Qing Xia the state Key Laboratory of Power Systems the Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Market participants can only bid with lagged information disclosure under the existing market mechanism,which can lead to information asymmetry and irrational market behavior,thus influencing market *** promote rational bidding behavior of market participants and improve market efficiency,a novel electricity market mechanism based on cloudedge collaboration is proposed in this *** market information,called residual demand curve,is published to market participants in real-time on the cloud side,while participants on the edge side are allowed to adjust their bids according to the information disclosure prior to closure *** proposed mechanism can encourage rational bids in an incentive-compatible way through the process of dynamic equilibrium while protecting participants’*** paper further formulates the mathematical model of market equilibrium to simulate the process of each market participant’s strategic bidding behavior towards equilibrium.A case study based on the IEEE 30-bus system shows the proposed market mechanism can effectively guide bidding behavior of market participants,while condensing exchanged information and protecting privacy of participants.

关键词： Cloud-edge collaboration market mechanism residual demand curve strategic bidding

Laminar Flame Structure-Dependent Exergy Destruction Behavior at Auto-Ignition Time Scale:A Case Study of Dimethyl Ether(DME)

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Journal of Thermal Science 2024年第4期33卷 1257-1271页

作者： WU Honghuan HUANG Wenlin ZHAO Hao SUN Wuchuan HUANG Zuohua ZHANG Yingjia state Key Laboratory of Multiphase Flow in Power engineering Xi’an Jiaotong UniversityXi’an710049China

Hybrid deflagration/auto-ignition flame structures coexist in the combustion of advanced *** exergy destruction caused by different irreversible processes under varied flame regimes is thus important for understanding engine *** this study,the flame propagation modes for the premixed DME/air mixtures are numerically investigated under engine-relevant *** entropy generation and exergy destruction characteristics are compared under different flame *** reveal that as the typical premixed flame transition towards auto-ignition front,the exergy destruction from heat conduction and species mass diffusion gradually vanish and are dominated by chemical *** distributions of temperature and species mole fraction in the flame domain are analyzed to clarify the exergy destruction behaviors caused by heat conduction and mass ***,by dividing the DME oxidation process into four stages,the main reaction channels that contribute to the increase in exergy destruction from chemical reaction have been *** is found that the production and consumption of CH_(2)O and HO_(2) radical dominate the exergy destruction behavior during DME *** this basis,the kinetic mechanism of low-temperature chemistry causing greater exergy destruction is ***,low-temperature chemistry leads to significant exergy destruction due to(a)the large irreversibility of itself and(b)(mainly)the enhancement of H_(2)O_(2)loop reactions by low-temperature reaction *** the reduction of combustion irreversibility is promising to be achieved by reasonably regulating the fuel oxidation path.

关键词： exergy destruction flame structures entropy generation low-temperature chemistry DME

Interparticle energy transfer between NaNdF_(4) and NaYbF_(4) in self-assembled nanostructures

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Journal of Rare Earths 2024年第6期42卷 1029-1035,I0001页

作者： Xinyu Chen Haoze Yang Yuyang Gu Chenqing Wen Yishuo Sun Jiaming Ke Wei Feng Department of Chemistry and state Key Laboratory of Molecular engineering of Polymers Fudan university Shanghai200433China

Forster resonance energy transfer(FRET)is a widely used spectroscopic *** development of donor-acceptor combinations is essential to advance this *** make the energy transfer efficiency independent of the external environment,we explored the potential of constructing donor—acceptor combinations with lanthanide ion-doped nanoparticles(LNPs),in which the 4f electrons of the lanthanide ions are shielded by the 5s and 6p ***-radiative energy transfer between LNPs was demonstrated in self-assembled nanostructures and core-shell structure of LNPs was used to control the distance between donor and acceptor in self-assembled *** emission intensity ratio of donor and acceptor illustrates that the energy transfer efficiency decreases significantly with increasing distance and the effective energy transfer distance is 8.5 nm,showing the potential of using LNPs as donor-acceptor pairs in the construction of distance-dependent energy transfer system.

关键词： Lanthanide nanoparticles Self-assembly Energy transfer Distance Epitaxialgrowth Rare earths

Sourcing the merits of 3D integrated air cathodes for highperformance Zn-air batteries by bubble pump consumption chronoamperometry

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Nano Research 2024年第8期17卷 6951-6959页

作者： Mengxuan Li Linfeng Yu Hai Liu Chuanyi Zhang Jiazhan Li Liang Luo Xiaoming Sun state Key Laboratory of Chemical Resource engineering Beijing University of Chemical TechnologyBeijing 100029China

Zn-air batteries(ZABs)as a potential energy conversion system suffer from low power density(typically≤200 mW·cm^(−2)).Recently,three-dimensional(3D)integrated air cathodes have demonstrated promising performance over traditional twodimensional(2D)plane ones,which is ascribed to enriched active sites and enhanced diffusion,but without experimental ***,we applied a bubble pump consumption chronoamperometry(BPCC)method to quantitatively identify the gas diffusion coefficient(D)and effective catalytic sites density(ρEC)of the integrated air cathodes for ***,the D andρEC values can instruct consequent optimization on the growth of Co embedded N-doped carbon nanotubes(CoNCNTs)on carbon fiber paper(CFP)and aerophilicity tuning,giving 4 times D and 1.3 timesρEC over the conventional 2D Pt/C-CFP *** a result,using the CoNCNTs with half-wave potential of merely 0.78 V ***(Pt/C:0.89 V ***),the superaerophilic CoNCNTs-CFP cathode-based ZABs exhibited a superior peak power density of 245 mW·cm^(−2) over traditional 2D Pt/C-CFP counterparts,breaking the threshold of 200 mW·cm^(−2).This work reveals the intrinsic feature of the 3D integrated air cathodes by yielding exact D andρEC values,and demonstrates the feasibility of BPCC method for the optimization of integrated electrodes,bypassing trial-and-error strategy.

关键词： Zn-air batteries three-dimensional(3D)integrated air cathodes superaerophilic gas diffusion coefficient effective catalytic sites density

Kinetics insights into size effects of carbon nanotubes'growth and their supported platinum catalysts for 4,6-dinitroresorcinol hydrogenation

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Chinese Journal of Chemical engineering 2024年第8期72卷 133-140页

作者： Yan Zhang Xiangxue Zhang Keng Sang Wenyao Chen Gang Qian Jing Zhang Xuezhi Duan Xinggui Zhou Weikang Yuan state Key Laboratory of Chemical engineering East China University of Science and TechnologyShanghai 200237China

Size effects are a well-documented phenomenon in heterogeneous catalysis,typically attributed to alterations in geometric and electronic *** this study,we investigate the influence of catalyst size in the preparation of carbon nanotube(CNT)and the hydrogenation of 4,6-dinitroresorcinol(DNR)using Fe_(2)O_(3)and Pt catalysts,*** Fe_(2)O_(3)/Al_(2)O_(3)catalysts were synthesized for CNT growth through catalytic chemical vapor *** findings reveal a significant influence of Fe_(2)O_(3)nanoparticle size on the structure and yield of ***,CNT produced with Fe_(2)O_(3)/Al_(2)O_(3)containing 28%(mass)Fe loading exhibits abundant surface defects,an increased area for metal-particle immobilization,and a high carbon *** makes it a promising candidate for DNR *** this catalyst support,we further investigate the size effects of Pt nanoparticles on DNR *** Pt catalysts demonstrate a preference for 4,6-diaminoresorcinol generation at(100)sites,whereas smaller Pt catalysts are more susceptible to electronic *** kinetics insights obtained from this study have the potential to pave the way for the development of more efficient catalysts for both CNT synthesis and DNR hydrogenation.

关键词： Kinetics Size effects Catalytic hydrogenation Active site

Experimental Study on Towing Characteristics of Composite Bucket Wellhead Platform

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China Ocean engineering 2024年第3期38卷 531-542页

作者： ZHANG Pu-yang LIU Ying-fei LE Cong-huan DING Hong-yan BAI Yu state Key Laboratory of Hydraulic engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China

With the rapid development of large-scale development of marginal oilfields in China,simple wellhead platforms that are simple in structure and easy to install have become an inevitable choice in the process of oilfield ***,traditional simple wellhead platforms are often discarded after a single *** pursuit of a more costeffective approach to developing marginal oilfields,this paper proposes a new offshore oil field development facility—an integrated bucket foundation for wellhead *** verify the safety of its towing behavior and obtain the dynamic response characteristics of the structure,this paper takes a bucket integrated bucket foundation for wellhead platform with a diameter of 40 m as the research *** combining physical model tests and numerical simulations,it analyzes the static stability and dynamic response characteristics of the structure during towing,complete with the effects of the draft,wave height,wave period,and towing point height,which produce the dynamic responses of the structure under different influence factors,such as roll angle,pitch angle,heave acceleration and towing force as well as the sensibility to transport *** results show that the integrated bucket foundation for wellhead platform is capable of self-floating towing,and its movement is affected by the local environment,which will provide a reference for actual projects.

关键词： composite bucket foundation wellhead platform air flotation towing model test