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Cuttings transport: Back reaming analysis based on a coupled layering-sliding mesh method via CFD

Petroleum Science 2023年第6期20卷 3673-3686页

作者： Na Zhu shi-Dong Ding Xiao-Lei Shi Wen-Jun Huang De-Li Gao MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China SINOPEC Research Institute of Petroleum Engineering Co.Ltd No.197 Baisha RoadChangping DistrictBeijing102206China

Inadequate hole cleaning is one of the main reasons for inefficient operations in extended-reach drilling.The mechanism of cuttings transport under the back reaming operation,which is frequently adopted to remove the cuttings,has been investigated in this study.To this end,a coupled layering-sliding mesh method with the Eulerian-Granular approach has been established innovatively.The dynamic layering method has been employed to simulate the axial motion of the pipe,whereas the sliding mesh method has been used to simulate the pipe rotation.The back reaming operation of a connector-furnished pipe has been simulated,and the sensitive parameter analysis has been conducted.The results thus obtained demonstrate that the increase in the initial bed height,inclination,and the diameter and length of the connector causes a significant increase in the cuttings concentration.In addition,the cuttings concentration is observed to decrease significantly with the pipe rotation speed.Furthermore,two main factors contribute towards the cuttings accumulation around the connector,namely,the difference in the cross-sectional area and the pushing effect of the connector—like a“bulldozer”.The“bulldozer”effect of the connector dominates when the tripping velocity is significant compared to the velocity of the cuttings.Conversely,the effect of the difference in the cross-sectional area becomes the leading factor for cuttings accumulation.The“bulldozer”effect of the connector causes a more severe impact on hole cleaning.In both cases,increasing the tripping velocity only mildly affects the cuttings concentration.It is therefore suggested that the tripping velocity should be slower than that of the sand during the back reaming operation.Furthermore,increased fluid velocity might lead to a higher accumulated cuttings concentration around the connector when the cuttings bed has not entirely passed through the connector.A significant flow rate can be safely applied after the cuttings have passed through the connector furnished with a large d

关键词： Drill cuttings transport Back reaming Layering-sliding mesh Hole cleaning Connector

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Mechanical behavior of drillstring with drag reduction oscillators and its effects on sliding drilling limits

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Petroleum Science 2021年第6期18卷 1689-1697页

作者： Xiao-Lei Shi Wen-Jun Huang De-Li Gao MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China

Practice has proved that drag reduction oscillators can decrease the axial friction and increase wellbore extension effectively in sliding drilling operations.However,the complicated mechanical behavior of drillstring with drag reduction oscillators has not been revealed sufficiently.In this paper,the mechanical model of drillstring with drag reduction oscillators is established by considering the friction nonlinearity.Further introducing the initial conditions,boundary conditions and continuity conditions,the finite differential equation of drillstring vibration is obtained and solved.The new model has been applied to a case study,in which the drag reduction effects of drillstring with and without oscillators are compared and the effects of relevant factors on drag reduction are analyzed.The results show that the hook loads increase obviously by reducing downhole average friction coefficient for drillstring with oscillators.Increasing vibration amplitude of the drag reduction oscillator can decrease axial friction,but the vibration frequency is nearly irrelevant to drag reduction.Increasing number of drag reduction oscillators can decrease axial friction,but may lead to large hydraulic power loss and high risk of drillstring fatigue.Therefore,there is an optimal number of drag reduction oscillators.The re search re sults are of significant guiding significance for optimal design and safety control in sliding drilling operations.

关键词： Drillstring Downhole oscillator Friction force Drag reduction Sliding drilling

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One-step post-treatment boosts thermoelectric properties of PEDOT:PSS flexible thin films

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Journal of Materials Science & Technology 2023年第1期132卷 81-89页

作者： Xingyu Liu Xiao-Lei Shi Li Zhang Wei-Di Liu Yanling Yang Zhi-Gang Chen School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China School of Chemistry and Physics Queensland University of TechnologyBrisbaneQLD 4000Australia Australian Institute for Bioengineering and Nanotechnology The University of QueenslandBrisbaneQLD 4072Australia

Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.

关键词： Thermoelectric PEDOT:PSS Post-treatment Dimethylacetamide L-ascorbic acid

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Flexible hollow TiO_(2)@CMS/carbon-fiber van der Waals heterostructures for simulated-solar light photocatalysis and photoelectrocatalysis

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Journal of Materials Science & Technology 2022年第3期98卷 143-150页

作者： Hua-Jun Chen Yan-Ling Yang Xin-Xin Zou Xiao-Lei Shi Zhi-Gang Chen School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China School of Environment and Chemistry Luoyang Institute of Science and TechnologyLuoyang 471000China Centre for Future Materials University of Southern QueenslandSpringfield CentralQLD 4300Australia School of Mechanical and Mining Engineering The University of QueenslandBrisbaneQLD 4072Australia

The recycling technology of photocatalyst powdery has hardly been mature in the photocatalytic oxidation so far.In this work,the hollow TiO_(2)microspheres with an appropriate thickness are confined in carbon microspheres(CMSs)to form hollow TiO_(2)@CMSs,which are physically integrated with carbon-fiber textile by van der Waals(vdW)interactions to generate separable and recyclable hollow TiO_(2)@CMSs/carbon-fiber vdW heterostructures.Such separable and recyclable heterostructures show remarkable oxidation of 2,4-dinitrophenol.From our detailed characterization and density functional theory(DFT)calculations,we found that carbon fiber can trap electrons exerted from the excitation of hollow TiO_(2)@CMSs and creates holes in hollow TiO_(2)microspheres,which endow the carbon fiber with photocatalytic activity through coherent charge injection.This study indicates that our general strategy for the fabrication of hollow TiO_(2)@CMSs/carbon-fiber vdW heterostructures can be used as separable and recyclable photocatalyst and photoelectrocatalyst with potential industrial applications in environmentrelated fields.

关键词： Hollow nanostructure TiO_(2) Carbon fiber van der Waals heterostructure Photoelectrocatalysis

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Revolution in thermoelectric cooling using PbSe thermoelectrics by grid plainification

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Science China Materials 2024年第5期67卷 1672-1673页

作者： Xiao-Lei Shi Qingfeng Liu Zhi-Gang Chen School of Chemistry and Physics ARC Research Hub in Zero-emission Power Generation for Carbon Neutralityand Centre for Materials ScienceQueensland University of Technology State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech University

Thermoelectric materials and devices enable direct conversion between heat and electricity, holding potential applications in thermoelectric power generation, localized cooling, and electronic thermal management [1]. However, despite widespread applications, thermoelectric technology remains constrained by material performance [2].

关键词： enable thermoelectric constrained

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Weavable thermoelectrics: advances, controversies, and future developments

Materials Futures

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Materials Futures 2024年第1期3卷 63-94页

作者： Xiao-Lei Shi Shuai Sun Ting Wu Jian Tu Zhiming Zhou Qingfeng Liu Zhi-Gang Chen School of Chemistry and Physics ARC Research Hub in Zero-emission Power Generation for Carbon Neutralityand Centre for Materials ScienceQueensland University of TechnologyBrisbaneQueensland4000Australia State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211800People’s Republic of China School of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054People’s Republic of China

Owing to the capability of the conversion between thermal energy and electrical energy and their advantages of light weight,compactness,noise-free operation,and precision reliability,wearable thermoelectrics show great potential for diverse applications.Among them,weavable thermoelectrics,a subclass with inherent flexibility,wearability,and operability,find utility in harnessing waste heat from irregular heat sources.Given the rapid advancements in this field,a timely review is essential to consolidate the progress and challenge.Here,we provide an overview of the state of weavable thermoelectric materials and devices in wearable smart textiles,encompassing mechanisms,materials,fabrications,device structures,and applications from recent advancements,challenges,and prospects.This review can serve as a valuable reference for researchers in the field of flexible wearable thermoelectric materials and devices and their applications.

关键词： thermoelectric weaving materials structure device

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A-site cation engineering enables oriented Ruddlesden-Popper perovskites towards efficient solar cells

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Science China Chemistry 2022年第12期65卷 2468-2475页

作者： Rui Liu Yue Yu Chang Liu Hua Yang Xiao-Lei Shi Hua Yu Zhi-Gang Chen Institute of Photovoltaics Southwest Petroleum UniversityChengdu610500China Institute of High Energy Physics Chinese Academy of Sciences(CAS)Beijing100049China School of Chemistry and Physics Queensland University of TechnologyBrisbaneQLD4001Australia

Quasi two-dimensional(Q-2D)perovskites with favorable environment stability and satisfied device performance are attracting great attention and becoming star materials.The unique characteristics of more wide range of Goldschmidt tolerance factor endow Q-2D perovskites with exceptional composition tunability and great potential.Herein,Guanidinium(Gua)was firstly introduced into the octahedral cation site of BA_(2)MA_(3)Pb_(4)I_(13) perovskite to partially replace methylammonium(MA).With the incorporation of Gua,the XRD intensity ratio of(202)/(111)increased nearly 100%for control and 0.10Gua-mixed Q-2D perovskite,from1.49 to 2.84,indicating that the layered perovskite crystallization orientation is significantly regulated.Coupling with GIWAXS results,a preferential orientation Q-2D perovskite film was obtained.Meanwhile,the Gua-based Q-2D perovskite exhibits significantly reduced nonradiative recombination,which greatly promotes the efficient transport of carriers leading to a high efficiency of 15.41%in the BA_(2)(MA_(0.9)GA_(0.1))_(3)Pb_(4)I_(13)-based solar cell.Moreover,the solar cells display superior environmental stability at an average humidity of 35%±5%in the air for 1200 h.This work points the way to the regulation of crystal orientation for enhancing the performance of Q-2D perovskite by the A-site cation engineering.

关键词： crystallographic orientation Q-2D perovskite cation engineering solar cell

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Bioartificial liver devices:Perspectives on the state of the art

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Frontiers of Medicine 2011年第1期5卷 15-19页

作者： Yi-Tao DING Xiao-Lei Shi Department of Hepatobiliary Surgery the Affiliated Drum Tower Hospital of the Nanjing University Medical SchoolNanjing 210008China

Acute liver failure remains a significant cause of morbidity and mortality.Bioartificial liver(BAL)devices have been in development for more than 20 years.Such devices aim to temporarily take over the metabolic and excretory functions of the liver until the patients’own liver has recovered or a donor liver becomes available for transplant.The important issues include the choice of cell materials and the design of the bioreactor.Ideal BAL cell materials should be of good viability and functionality,easy to access,and exclude immunoreactive and tumorigenic cell materials.Unfortunately,the current cells in use in BAL do not meet these requirements.One of the challenges in BAL development is the improvement of current materials;another key point concerning cell materials is the coculture of different cells.The bioreactor is an important component of BAL,because it determines the viability and function of the hepatocytes within it.From the perspective of bioengineering,a successful and clinically effective bioreactor should mimic the structure of the liver and provide an in vivo-like microenvironment for the growth of hepatocytes,thereby maintaining the cells’viability and function to the maximum extent.One future trend in the development of the bioreactor is to improve the oxygen supply system.Another direction for future research on bioreactors is the application of biomedical materials.In conclusion,BAL is,in principle,an important therapeutic strategy for patients with acute liver failure,and may also be a bridge to liver transplantation.It requires further research and development,however,before it can enter clinical practice.

关键词： acute liver failure bioartificial livers hepatocyte bioreactor

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Low-carbon transition of iron and steel industry in China:Carbon intensity, economic growth and policy intervention

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Journal of Environmental Sciences 2015年第2期27卷 137-147页

作者： Bing Yu xiao Li Yuanbo Qiao lei shi State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University School of Economics and Management Tsinghua University

As the biggest iron and steel producer in the world and one of the highest CO2 emission sectors, China’s iron and steel industry is undergoing a low-carbon transition accompanied by remarkable technological progress and investment adjustment, in response to the macroeconomic climate and policy intervention. Many drivers of the CO2 emissions of the iron and steel industry have been explored, but the relationships between CO2 abatement,investment and technological expenditure, and their connections with the economic growth and governmental policies in China, have not been conjointly and empirically examined. We proposed a concise conceptual model and an econometric model to investigate this crucial question. The results of regression, Granger causality test and impulse response analysis indicated that technological expenditure can significantly reduce CO2 emissions, and that investment expansion showed a negative impact on CO2 emission reduction. It was also argued with empirical evidence that a good economic situation favored CO2 abatement in China’s iron and steel industry, while achieving CO2 emission reduction in this industrial sector did not necessarily threaten economic growth.This shed light on the dispute over balancing emission cutting and economic growth.Regarding the policy aspects, the year 2000 was found to be an important turning point for policy evolution and the development of the iron and steel industry in China. The subsequent command and control policies had a significant, positive effect on CO2 abatement.

关键词： CO2emission reduction Iron and steel industry Economic growth China Vector autoregression（VAR）

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Mechanism investigation and strategies for reducing residual stress at open ends of the roll-formed part

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宝钢技术研究:英文版 2023年第3期17卷 25-31页

作者： XU Dongkai shi lei xiao Hua Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel) Shanghai 201999China

Increasing geometrical accuracy at open ends of the roll-formed part is difficult due to the release of residual stress after end cutting.In this work,a typical rail with a high requirement of geometry accuracy was selected to realize the behaviors of residual stress release.First,residual stress distribution after roll forming is discussed in detail by finite element analysis with ABAQUS.In addition,two different approaches are proposed to check their capabilities in reducing the residual stress level.The results indicate that both additional rolling passes and multiple bending processes are beneficial to reducing uniform residual stress.

关键词： roll forming ultra-high-strength steel residual stress

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