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Effect of damage zone around borehole on carbon dioxide injection promoted gas extraction in soft and low-permeability coal seam

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Frontiers of Earth Science 2023年第3期17卷 776-787页

作者： lijun zhou Xihua zhou Gang BAI Xianlin LI Mingkun LUO College of Safety Science and Engineering Liaoning Technical UniversityFuxin 123000China Key Laboratory of Mine Thermodynamic Disasters and Control(Ministry of Education) Fuxin 123000China

Injecting external CO_(2) into soft and low-permeability coal seams can improve CH4 extacctinn efficiency, and also benefit in CO_(2) sequestration. However, the distribution law of damage zone around borehole in soft coal seam and its effect on the efficiency of CO_(2) injection promoted CH4 extraction are not clear. In this paper, a multi-physics coupling mathematical model considering damage effect is established for simulating the process of CO_(2) injection promoted CH4 extraction in soft and low-permeability coal seam. The distribution of damage zone and permeability around boreholes under different diameters and coal strengths are analyzed. The gas pressure and gas content in coal seam during CO_(2) injection promoted CH4 extraction when the model considered damage effect are compared with that of ignored. The results show that small borehole diameter corresponds to narrow damage zone around the borehole in coal seam. The damage zone expands with the increase of the borehole diameter. The damage zone increases exponentially with the borehole diameter, while decreases exponentially with the compressive strength of coal seam. The highest permeability in the damage zone has increased by nearly 300 times under the condition of simulated case. CH4 pressure around the extraction borehole reduces, and the reduction area expands with the increase of time. Compared with the result of considering the damage effect, the reduction area of ignoring it is smaller, and the reducing speed is slower. The integrated effect of CO_(2) injection and CH4 extraction leads to rapid decrease of CH4 content in coal seam near the boreholes. The CO_(2) pressure and content increase around the injection borehole, and the increasing area gradually extends to the whole coal seam. In soft coal seams, failure to consider the damage effect will underestimate the efficiency of CH4 extraction and CO_(2) sequestration, resulting conservative layout of boreholes.

关键词： soft and low-permeability coal seam carbon dioxideinjection gas extraction damageeffect permeability evolution

Analysis of flow and heat transfer characteristics of micro-pin fin heat sink using silver nanofluids

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Science China(Technological Sciences) 2012年第1期55卷 155-162页

作者： zhou MingZheng XIA GuoDong CHAI Lei LI Jian zhou lijun Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of Education College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China

Silver nanofluids with three different volume fractions are prepared by a one-step chemical reduction method(Ultra-sound-assisted Membrane Reaction(UAMR)).The convective heat transfer and friction characteristics of silver nanofluid in micro-pin fin heat sink are investigated *** results indicate that the pressure drops of nanofluids with different volume fractions have little *** to the base fluid(polyvinylpyrrolidone(PVP) solution),the pressure drop of nanofluids increases slightly at the same volume flow *** the flow rate is small,the increment is not *** in-troduction of surfactant increases the fluid viscosity,so the pressure drops of nanofluids are larger than those of pure water,under the same flow ***,the maximum difference is no more than 10%.The volume fraction of silver nanoparticles significantly affects the convection heat transfer coefficient of micro-pin fin heat *** presence of nanoparticles improves significantly the heat transfer ***,high viscosity of the nanofluids hinders the heat transfer strengthening effect of *** the present work,when the volume fraction of silver particles reaches to 0.012%,the thermal resistance of nanofluid gradually becomes lower than that of deionized water,which indicates the integrated heat transfer enhancement of nanofluids.

关键词： nanofluids micro-pin fin heat transfer viscosity volume fraction

Transient thermal network model for train-induced wind cooling dry-type on-board traction transformer in electric multiple units

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High Voltage 2023年第3期8卷 514-526页

作者： lijun zhou Shuai Yuan Qiuyue Zhu Dongyang Wang Lujia Wang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina School of Electrical and Power Engineering China University of Mining and TechnologyXuzhouChina

Thermal characteristic is one of the key performances of dry-type on-board traction transformer(D-OBTT),which directly affects the operation safety of the new generation electric multiple ***,due to the particularity of train-induced wind cooling mode of D-OBTT,the existing efficient thermal modelling methods cannot be used under fluctuating air velocity and load.A time-saving transient thermal model for D-OBTT is ***,the framework of the transient thermal network model(TTNM)is proposed considering the coexistence of non-fully and fully developed state of the train-induced wind and the addition heat flow in the solid ***,a novel formula for calculating the length of non-fully developed section considering the geometric dimensions and heat flux density is proposed based on computational fluid dynamics(CFD)parametric sweeps for the first *** accuracy of TTNM is validated by a D-OBTT experimental setup,and the time consumption is significantly reduced compared with CFD.

关键词： traction network thermal

Experimental study on ageing characteristics of electric locomotive ethylene propylene rubber cable under mechanical-thermal combined action

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High Voltage 2022年第4期7卷 792-801页

作者： lijun zhou Cong Liu Shengwei Quan Xiangyu Zhang Dongyang Wang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The train-mounted ethylene propylene rubber(EPR)cables of electric locomotive are partly restricted by the body structure and spatial layout and are in a combined envi-ronment of strong mechanical bending and thermal *** degradation character-istics of the insulation layer have not yet received sufficient *** order to study the ageing characteristics of EPR cables of electric locomotive under the combined action of machine and thermal,this paper designs a bending-thermal combined ageing test platform for cables with a temperature of 135°C,bending diameter of 393.52 mm,590.28 mm and unbending cables,and tests after *** product has been tested by infrared spectroscopy,scanning electron microscopy,elongation at break and broadband dielectric *** research results show that the bending outer part of the train-mounted EPR cable is a pain *** the combined action of bending and thermal,whether it is microstructure or macro performance,the degradation rate and degree of the bending of outer insulation layer are greater than the value under a single thermal ageing *** bending has an accelerating effect on the ageing of the EPR insulation *** research results can provide a reference for the ageing characteristics of the train-mounted EPR cable under the bending-thermal synergy and the evaluation of operating state of the train-mounted EPR cable under bending-thermal operating conditions.

关键词： microstructure thermal bending

Edge engineering in chemically active two-dimensional materials

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Nano Research 2022年第11期15卷 9890-9905页

作者： lijun zhou Mengyan Li Wei Wang Cong Wang Huiping Yang Yang Cao State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials(iChEM)College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China

When "cut off" continuous and uniform basal plane of two-dimensional(2D)materials,edges appear at *** edges with unique one-dimensional(1D)structures and bound-states significantly alter materials’local chemical activities and have been extensively investigated as model platforms for investigating structure–property–performance relationships for *** interesting phenomena have been discovered in the past decades,highlighting the importance of interactions between active species and edge atoms at the atomic level and making 1D edges as emerging catalysts with high efficiency,promising candidates for battery and electrochemical ***,this review focuses on the recent progress of edge synthesis and structural engineering methods,understanding of edge structure–activity mechanisms,and potential applications using edge *** and prospects are also envisioned.

关键词： two-dimensional(2D)materials one-dimensional(1D)edges relation of structure-activity

Tetra-alkylsulfonate functionalized poly(aryl ether) membranes with nanosized hydrophilic channels for efficient proton conduction

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Journal of Energy Chemistry 2020年第1期29卷 57-64,I0003页

作者： lijun zhou Junyang Zhu Meijin Lin Jiaqi Xu Zailai Xie Dongyang Chen College of Materials Science and Engineering Fuzhou UniversityFuzhou 350116FujianChina PowerChina Railway Construction Co. LtdBeijing 100037China College of Chemistry Fuzhou UniversityFuzhou 350116FujianChina

The microstructure of polymer electrolyte membranes plays a key role in ion conductivity and water ***,fluorinated poly(aryl ether)s with tetra-alkylsulfonate side chains(SFPAEs)have been successfully synthesized from the copolymerization of a newly developed tetra-allyl-containing bisphenol(TABP)monomer,followed by the thiol-ene addition with sodium 3-mercapto-1-propanesulfonate to attach the ionic groups at the end of the flexible *** the first of its kind,the densely distributed and lengthy alkylsulfonate group possesses the benefit of ease to self-assemble into hydrophilic domains during membrane preparation via solution ***,the TEM characterizations revealed that distinct hydrophilic channels of 1-2 nm width had been formed,much larger than those of a home-made control sample where only di-alkylsulfonate side chains were *** SFPAE-4-45 with an IECw of 2.0 mmol g^-1 exhibited an enhanced proton conductivity of 143.7 m S cm^-1 at room temperature,which was superior to that of Nafion 212(91.0 m S cm^-1).Furthermore,the oxidative stabilities of SFPAEs were significantly higher than those of non-fluorinated analogs in *** study offered a new route to engineering the pendent structure of ionomers for well-defined microscopic morphologies.

关键词： Proton exchange membrane Poly(arylene ether) Nano-phase separation Thiol-ene addition

Fast Protection Strategy for DC Transmission Lines of MMC-based MT-HVDC Grid

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Chinese Journal of Electrical Engineering 2021年第2期7卷 83-92页

作者： Sihua Wang lijun zhou Tian Wang Tianyu Chen Yu Wang College of Automation&Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China Rail Transit Electrical Automation Engineering Laboratory of Gansu Province Lanzhou Jiaotong UniversityLanzhou 730070China

Multi-terminal high voltage DC(MT-HVDC)grid has broad application prospects in connecting different energy sources,asynchronous interconnection of power grids,remote load power supply,and other *** present,the key technologies that affect the development of MT-HVDC transmission system include swift fault identification and location in the DC line and its rapid *** fault monitoring relies on line communication,which cannot guarantee the rapidity and reliability of protection;moreover,it may even cause device damage.A fault identification scheme based on a single-terminal transient is presented in this *** scheme calculates the line inductance by using the rise rate of fault current at the initial stage of the fault,and determines the occurrence of the fault by comparing the observed line inductance with the set value,which lays a foundation for calculating the location of the fault point using distance protection.A simulation model on the PSCAD/EMTDC platform is built;the simulation example verifies that the proposed scheme can identify faults under dissimilar conditions while maintaining a low error level on the premise of no communication lines so as to meet the protection requirements of the MT-HVDC grid.

关键词： Multi-terminal high voltage DC(MT-HVDC)grid modular multilevel converter(MMC) DC circuit breaker(DCCB) bipolar short-circuit fault identification

Literature review of driving risk identification research based on bibliometric analysis

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第4期10卷 560-577页

作者： Huimin Ge Yunyu Bo Wenkai Zang lijun zhou Lei Dong School of Automotive and Traffic Engineering Jiangsu UniversityZhenjiang 212013China

In order to understand the current research status and development direction of driving risk identification at home and abroad,relevant literatures in the field of driving risk identification from the China National Knowledge Infra-structure(CNKI)and Web of Science(WOS)in recent 12 years(2011-2022)were selected as research samples,and literature metrology tools VOSviewer and Citespace were used for visual *** situation was analyzed from the aspects of chronological distribution,national cooperation network,distribution of domestic institutions,journal performance and keywords overview,literature coupling clustering and research *** results show that the number of published papers fluctuates year by year,and China,the United States and Germany have the largest number of published *** United States is at the center of international *** CNKI shows that universities in China such as Chang’an University and Chongqing Jiaotong University have published a large number of *** to the statistics of WOS,Accident Analysis&Prevention is the most widely published journal in the *** average level of the journal is high and the quality of articles is *** the research contents of CNKI and WOS,the main research directions can be clustered into five cluster themes by using the coupling function in VOSviewer,including driving risk assessment considering driver factors,the influence of driving environment on driving risk,driving risk assessment considering multi-source characteristic data,multiaspect research on driving risk and risk identification of non-traditional vehicles in specific ***-machine co-driving,artificial intelligence,intelligent driving,risk identification and natural driving are the current research hotspots and the future research trends.

关键词： Traffic safety Bibliometric analysis Driving risk identification Developing state Literature coupling

Degree of polymerisation estimation for insulation paper immersed in silicone oil using frequency domain dielectric spectroscopy

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High Voltage 2023年第5期8卷 1041-1054页

作者： lijun zhou Jun Zhang Zhixin Li Rongting Wen Dongyang Wang Jiekang Wu Huiling Tang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina School of Automation Guangdong University of TechnologyGuangzhouChina School of Physics and Optoelectronic Engineering Guangdong University of TechnologyGuangzhouChina

Frequency domain dielectric spectroscopy(FDS)is an effective method reflecting the changes of ageing status of silicone oil‐immersed insulation *** better evaluating the ageing status of silicone oil‐immersed insulation paper,an evaluation method was studied by analysing the ageing kinetic model and results of ***,the method to separate the different polarization losses and conductivity loss from the results of FDS was ***,based on the idea of ageing correction translation coefficient and timevarying pre exponential factor,the zero order ageing dynamic model was modified,which combines the ageing kinetic model with the results of ***,the evaluation method for the degree of polymerisation(DP)of silicone oil‐immersed paper was proposed,and experiments were conducted to obtain the parameters in the modified model and then to verify the proposed *** results show that the proposed method can be used to evaluate the DP effectively.

关键词： immersed insulation spectroscopy