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An intrinsic kinetics model to predict complex ash effects (ash film, dilution, and vaporization) on pulverized coal char burnout in air (O2/N2) and oxy-fuel (O2/CO2) atmospheres

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PROCEEDINGS OF THE COMBUSTION INSTITUTE 2019年第3期37卷 2781-2790页

作者： Niu, Yanqing Liu, Siqi Shaddix, Christopher R. Hui, Shi'en Xi An Jiao Tong Univ Sch Energy & Power Engn Dept Thermal Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Sandia Natl Labs Combust Res Facil Livermore CA 94550 USA

During coal combustion, char chemical reaction is the slowest step, particularly in the last burnout stage, where the char consists of small amounts of carbon in a predominant ash framework. Existing kinetics models tend to deviate from experimental measurements of late char burnout due to the incomplete treatment of ash effects. Ash can improve pore evolution through vaporization, hinder oxygen transport by forming an ash film, and reduce active carbon sites and available surface per unit volume by penetrating into the char matrix. In this work, a sophisticated kinetics model, focusing on these three ash evolution mechanisms (ash vaporization, ash film, and ash dilution) during pulverized coal (PC) char combustion, is developed by integrating them into a thorough mechanistic picture. Further, a detailed comparison of the three distinct ash effects on PC char conversion during air (O-2/N-2) and oxy-fuel (O-2/CO2) combustion is performed. For the modeled coal, the mass of ash vaporization is approximate 3 orders less than the mass of ash remaining, which participates in ash dilution and ash film formation, both in O-2/N-2 and O-2/CO2 atmospheres. The influence of these phenomena on burnout time follows the order: ash dilution > ash film > ash vaporization. The influence of ash vaporization on burnout time is minor, but through interactions with the ash dilution and ash film forming processes it can have an impact at high extents of burnout, particularly in O-2/CO2 atmospheres. In O-2/N-2 atmospheres the residual ash predominately exists as an ash film, whereas it mainly exists as diluted ash in the char matrix in O-2/CO2 atmospheres. The residual ash particle is encased by a thick film when the ash film forming fraction is high (low ash dilution fraction). These results provide in-depth insights into the conversion of PC char and further utilization of the residual ash. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

关键词： Ash Char combustion Ash film Ash dilution Ash vaporization

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Observation based study on atmospheric oxidation capacity in Shanghai during late-autumn: Contribution from nitryl chloride

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ATMOSPHERIC ENVIRONMENT 2022年 271卷 118902-118902页

作者： Lou, Shengrong Tan, Zhaofeng Gan, Guicheng Chen, Jun Wang, Haichao Gao, Yaqin Huang, Dandan Huang, Congyan Li, Xiaoqian Song, Ruifeng Wang, Hongli Wang, Meng Wang, Qian Wu, Yuhang Huang, Cheng Shanghai Acad Environm Sci State Environm Protect Key Lab Format & Prevent U Shanghai 200233 Peoples R China Forschungszentrum Julich Inst Energy & Climate Res IEK 8 Troposphere D-52428 Julich Germany Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Sun Yat Sen Univ Sch Atmospher Sci Guangzhou Peoples R China Minist Educ Southern Marine Sci & Engn Guangdong Lab Zhuhai Guangdong Prov Observat & Res Stn Climate Environ Key Lab Trop Atmosphere Ocean Syst Zhuhai Peoples R China Chinese Res Inst Environm Sci State Key Lab Environm Criteria & Risk Assessment Beijing 100012 Peoples R China

Atmospheric oxidation processes are important to convert freshly emitted trace gases to secondary pollutants. ROx radicals (including hydroxyl radical (OH), hydroperoxyl radical (HO2), and organic peroxyl radical (RO2)) dominate the atmospheric oxidation capacity. In this study, measurements of RO(x & nbsp;& nbsp;)chemistry precursors and products are presented in Shanghai, a megacity in eastern China during late autumn. During the campaign, two types of air masses are identified, one of which is warm air parcel characterized by relatively higher concentrations of particulate matters and ozone. An observational based chemical box model is utilized to simulate the radical chemistry. HONO is the most important radical source contributing more than one-third of the total radical primary source. However, alkene ozonolysis reactions not only serve as a non-photolytic source but also become relative important during polluted cases indicating the important role in polluted conditions. The maximum ClNO2 was 0.4 ppbv (5min averaged) with a 1h diurnal averaged maximum of 0.16 ppbv and 0.06 ppbv for polluted and clean cases, respectively. The contribution of ClNO2 photolysis to the total primary radical production is < 1% on 24h averaged based. Though the campaign was conducted in late autumn when ClNO2 was considered as a relatively important radical source compared to summer conditions, our results suggest the contribution of ClNO2 may vary from case to case. The role of Cl radical and OH radical in secondary pollution formation is explored. Although the model predicts that the concentrations of Cl radicals are orders of magnitude smaller than that of OH radicals, further model analysis highlight that the ozone production per VOC oxidation is more efficient due to Cl radical initiated the reaction chain compared to OH radical. The ubiquitous presence of ClNO2 with large spatial and temporal variability demonstrates that the contribution of ClNO2 to photochemical processes sh

关键词： Atmospheric Oxidation Capacity (AOC) Ozone production Nitryl Chloride Shanghai

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Compositional Variations in Highly Active Ptsn/Al2o3 Catalysts Derived from Molecular Complexes

SSRN

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SSRN 2023年

作者： He, Qian Xu, Chaokai Tan, Shengdong Tang, Yaxin Xi, Shibo Yao, Bingqing Wade, Austin Zhao, Binbin Lu, Shangchen Tian, Mingjiao He, Chi Ma, Lu Fu, Xingjie Shi, Jiwei Lu, Jiong Howe, Alexander G.R. Dai, Sheng Luo, Guangfu Du, Yankun Department of Material Science and Engineering College of Design and Engineering National University of Singapore 9 Engineering Drive 1 EA #03-09 Singapore117575 Singapore Department of Materials Science and Engineering Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and Technology Guangdong Shenzhen518055 China 1 Pesek Road Jurong Island 627833 Singapore Thermo Fisher Scientific 5350 NW Dawson Creek Drive HillsboroOR United States State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Brookhaven National Laboratory UptonNY11973 United States Department of Chemistry National University of Singapore 12 Science Drive 2 117549 Singapore Key Laboratory for Advanced Materials Joint International Research Laboratory of Precision Chemistry and Molecular Engineering School of Chemistry and Molecular Engineering East China University of Science & Technology Shanghai200237 China

We investigated the industrially important PtSn/Al2O3 catalysts prepared with uniform particle sizes (~ 1 nm) and varied compositions using molecular complexes of Pt(II) and Sn(II). Our best catalyst, with a Sn:Pt ratio of around 2, exhibited a high initial propylene productivity of about 1.1 mol C3H6 (g catalyst)-1 h-1. Elaborate electron microscopy studies revealed significant compositional variations in the catalyst, highlighting the practical challenges in achieving or confirming the theoretically predicted optimum Sn:Pt ratio. It is also found that the catalytic activities correlate well with the Pt dispersion, suggesting the structure-insensitive nature of the dehydrogenation reaction applies in these ultrasmall Pt-Sn nanoparticles. The presence of Pt-rich particles in the catalysts did not produce noticeable degradations in the reaction selectivity, indicating a wide composition range for Pt-Sn nanoparticles to be effective at the 1 nm size range. These findings emphasize the importance of detailed analysis of compositional distributions for understanding nanoalloys. © 2023, The Authors. All rights reserved.

关键词： Electron microscopy

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Co3O4 Hybrid Electrocatalysts;Materials Description and Mechanistic Aspects Toward Hydrogen Production, Oxygen Evolution-Reduction, and CO2 Reduction Reactions

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CHEMICAL RECORD 2025年第3期25卷 e202400166页

作者： Tahira, Aneela Padervand, Mohsen Dawi, Elmuez Aftab, Umair Ghasemi, Shahnaz Vigolo, Brigitte Tonezzer, Matteo Bidmeshkipour, Samina Baghernejad, Masoud labidi, Abdelkader Lichtfouse, Eric Wang, Chuanyi Vomiero, Alberto Ibupoto, Zafar Hussain Shah Abdul Latif Univ Khairpur Mirs Inst Chem Sindh Pakistan Univ Maragheh Dept Chem Fac Sci POB 55181-83111 Maragheh Iran Guangzhou Inst Ind Intelligence GIII Evnironm & Energy Catalysis Lab Guangzhou 511400 Peoples R China Ajman Univ Coll Humanities & Sci Dept Math & Sci POB 346 Ajman U Arab Emirates Mehran Univ Engn & Technol Dept Met & Mat Engn Jamshoro 76080 Sindh Pakistan Sharif Univ Technol Sharif Energy Water & Environm Inst Azadi AvePOB 11365-8639 Tehran Iran Univ Lorraine CNRS IJL F-54000 Nancy France Univ Cagliari Dept Chem & Geol Sci Campus Monserrato I-09042 Monserrato CA Italy Sharif Univ Technol Dept Energy Engn Azadi AvePOB 11365-8639 Tehran Iran Forschungszentrum Julich Helmholtz Inst Munster IEK 12 Corrensstr 46 D-48149 Munster Germany Shaanxi Univ Sci & Technol Sch Environm Sci & Engn Xian 710021 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Lulea Univ Technol Dept Engn Sci & Math Div Mat Sci Lulea Sweden Ca Foscari Univ Venice Dept Mol Sci & Nanosyst Venice Italy Univ Sindh Jamshoro Inst Chem Sindh 76080 Pakistan

Controlling the adverse effects of global warming on human communities requires reducing carbon dioxide emissions and developing clean energy resources. Fossil fuel overuse damages the environment and raises sustainability concerns. As a resource-rich element, cobalt oxide hybrids have attracted considerable attention as low-priced and eco-friendly electrocatalysts. Alkaline solutions disperse Co3O4 easily despite its highly stable nature, which arises from the reverse spinel structures of Co. Metal oxides, nickel foam, polymeric frameworks, and carbon nanotubes have been successfully served to combine with the Co3O4 constructions for improving the electrocatalytic performance. To date, no comprehensive study has systematically investigated the relation between the cobalt oxide hybrid's physicochemical-electronic aspects and its catalytic features. This review mainly focuses on material design, fabrication, morphology, structural characteristics, and electroactivity, considering the critical factors towards practical applications. The economic impacts of the constructions and their expected contribution to large-scale utilizations are also demonstrated. Moreover, this research discusses the synergistic effects of crucial electrochemical parameters on sustainable energy production over the Co3O4-based hybrids. Finally, some beneficial conclusive suggestions are made based on emerging factors for real-world application. Future research in the field aiming at developing sustainable and clean energy production technologies can effectively benefit from the findings of this report.

关键词： Co3O4 Electrocatalysis Hybrid materials Clean energy Sustainable technologies

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Magneto-optical transmission in magnetic nanoparticle suspensions for different optical applications: a review

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JOURNAL OF PHYSICS D-APPLIED PHYSICS 2021年第1期54卷

作者： Jing, Dengwei Sun, Le Jin, Jingyu Thangamuthu, Madasamy Tang, Junwang Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Peoples R China UCL Dept Chem Engn London WC1E 7JE England

Recently, the magneto-optical properties of magnetic nanofluids have received increasing attention due to their wide range of applications in solar energy conversions and also as smart fluids in tunable photonic devices, optical switch, optical fiber sensor, etc. This review discusses up-to-date developments in magneto-optical transmission in ferrofluids. The magnetic nanoparticle would undergo various structural transitions under external magnetic field, including chainlike formation and lateral coalescence which, in turn, leads to various interesting light transmission phenomena. It is thus possible to alter the properties of the transmitted light by adjusting the orientation of the magnetic field with respect to that of the incident light. The polarization direction of light has a negligible effect on the magneto-optical transmission while light passing along the magnetic field. However, it makes a significant difference for light normal to the field direction. These characteristics are comprehensively reviewed, and their potential applications are presented. It is supposed to provide a general view on the research trends, existing problems and future work for the investigation of magneto-optical transmission in magnetic nanofluids.

关键词： magnetic nanofluids magneto-optical transmission transmitted light intensity particle aggregation

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Investigating cohesive sediment dynamics in open waters via grain-resolved simulations

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flow 2023年第1期3卷 E24-E24页

作者： Vowinckel, Bernhard Zhao, Kunpeng Zhu, Rui Meiburg, Eckart Tech Univ Carolo Wilhelmina Braunschweig Leichtweiss Inst Hydraul Engn & Water Resources D-38106 Braunschweig Germany Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Calif Santa Barbara Dept Mech Engn Santa Barbara CA 93106 USA Zhejiang Univ Ocean Coll Zhoushan 316021 Peoples R China

Cohesive particulate flows play an important role in environmental fluid dynamics, as well as in a wide variety of civil and process engineering applications. However, the scaling laws, constitutive equations and continuum field descriptions governing such flows are currently less well understood than for their non-cohesive counterparts. Grain-resolved simulations represent an essential tool for addressing this shortcoming, along with theoretical investigations, laboratory experiments and field studies. Here we provide a tutorial introduction to simulations of fine-grained sediments in viscous fluids, along with an overview of some representative insights that this approach has yielded to date. After a brief review of the key physical concepts governing van der Waals forces as the main cohesive effect for subaqueous sediment suspensions, we discuss their incorporation into particle-resolved simulations based on the immersed boundary method. We subsequently describe simulations of cohesive particles in several model turbulent flows, which demonstrate the emergence of a statistical equilibrium between the growth and break-up of aggregates. As a next step, we review the influence of cohesive forces on the settling behaviour of dense suspensions, before moving on to submerged granular collapses. Throughout the article, we highlight open research questions in the field of cohesive particulate flows whose investigation may benefit from grain-resolved simulations.

关键词： Sediment transport Cohesive sediments Computational methods

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flow regime identification of swirling gas-liquid flow with image processing technique and neural networks

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CHEMICAL engineering SCIENCE 2019年 199卷 588-601页

作者： Liu, Li Bai, Bofeng Shanghai Jiao Tong Univ Sch Nucl Sci & Engn Shanghai 200240 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Swirling flow is one of the commonly-recognized techniques to control working processes in various engineering fields. A fundamental understanding of the swirling flow pattern is significantly important for proper design, operation and optimization of swirling flow systems. Although a large amount of work has been done on conventional non-swirling two-phase flow, investigations on swirling flow regime classification are still scarce. In this paper, a visualization experiment was carried out to study the gas-liquid flow in a vertical pipe containing a swirler with four helical vanes. The typical flow regimes in swirling gas-liquid flow were first classified and defined by visual observation. Subsequently, the liquid holdup was measured with the proposed image processing technique and statistically analyzed through PDF and CPDF. Owing to its integral and stable feature, CPDF was then utilized along with a self-organizing neural network (SONN) to identify the swirling flow regimes objectively. Finally, a swirling flow regime map was proposed and compared with the previous non-swirling and swirling maps available in the publications. Based on this study, the influence of the centrifugal force on phase distribution of gas-liquid flow was clarified and the general relationship between swirling gas-liquid flow and non-swirling gasliquid flow was concluded. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Swirling gas-liquid flow flow regime map Liquid holdup Image processing Neutral network

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Catalytic total oxidation of toluene over carbon-supported Cu-Co oxide catalysts derived from Cu-based metal organic framework

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POWDER TECHNOLOGY 2020年 363卷 95-106页

作者： Li, Jian-Rong Wang, Feng-Kang He, Chi Huang, Cenyan Xiao, Hang Chinese Acad Sci Ctr Excellence Reg Atmospher Environm Xiamen 361021 Peoples R China Chinese Acad Sci Inst Urban Environm Key Lab Urban Environm & Hlth Xiamen 361021 Peoples R China Chinese Acad Sci Ningbo Urban Environm Observat & Res Stn Ningbo 315800 Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ Chinese Acad Sci Natl Engn Lab VOCs Pollut Control Mat & Technol Beijing 101408 Peoples R China

A series of carbon-supported Cu-Co oxide catalysts (Cu-Co/C) were prepared via the combination methods of impregnation and pyrolysis using Co-doped Cu-based metal organic framework (Cu-3(BTC)(2)center dot 3H(2)O, Cu-BTC) precursor. Physicochemical properties of prepared catalysts were characterized by using various technologies and toluene was chosen as the probe molecule to evaluate their catalytic performance. Results revealed that the successive calcination in Ar and air was conducive to the formation of 3D porous carbon matrix and homogeneous elemental dispersion. The Cu-Co/C catalysts with spinel structure exhibited higher catalytic activity than that of Cu-500/C material. Moreover, CuCo0.5/C material exhibited superior catalytic durability and water resistance in catalytic oxidation of toluene. The excellent catalytic performance of CuCo0.5/C was mainly related to large specific surface area, high amounts of surface chemisorbed active oxygen and high ratio of Co2+/Co3+. (c) 2020 Elsevier B.V. All rights reserved.

关键词： Cu-Co/C catalyst MOFs VOCs Toluene Catalytic oxidation

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Numerical Simulation of Quasi-Static Bubble Formation from a Submerged Orifice by the Axisymmetric VOSET Method

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MICROGRAVITY SCIENCE AND TECHNOLOGY 2019年第3期31卷 279-292页

作者： Wang, Tai Li, Hui-Xiong Zhao, Jian-Fu Guo, Kai-Kai North China Elect Power Univ Sch Energy Power & Mech Engn Baoding 071003 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Chinese Acad Sci Inst Mech CAS Key Lab Micrograv Beijing 100190 Peoples R China

In order to investigate the dynamics of quasi-static bubble formation from a submerged orifice, this paper developed an axisymmetric VOSET method with continuum surface force (CSF) model which can accurately capture the moving phase interface of gas-liquid flow. Test case shows that numerical results are in good agreement with experimental results from the literature. The effects of gas flow rate, orifice size, surface tension, contact angle, liquid density, and gravitational acceleration on bubble shape, departure time and departure volume are investigated and analyzed. It is found that increase in orifice size, surface tension, and contact angle results in the increase in the capillary force resisting bubble detachment, which leads to larger departure time and departure volume. But there is a critical contact angle, and contact angle has no significance effect on the process of bubble formation and detachment, when it is smaller than the critical value. Buoyancy force promoting bubble detachment increases with the increase of liquid density and gravitational acceleration, which results in smaller departure time and departure volume. Also, the forming process of the neck shape of bubble bottom at the bubble detachment stage is observed, and the results show that the position of the smallest part of the neck approximately equals to the orifice radius R-c.

关键词： Axisymmetric VOSET method Bubble formation Bubble detachment Static contact angle Numerical simulation

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Effects of gasification condition on the overall performance of methanol electricity polygeneration system

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ENERGY CONVERSION AND MANAGEMENT 2019年 184卷 362-373页

作者： Qin, Zhen Bhattacharya, Sankar Tang, Kai Zhang, Zaoxiao Xi An Jiao Tong Univ Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Monash Univ Dept Chem Engn Clayton Vic 3800 Australia

The operating conditions of coal gasifier have significant effects on the overall system performance of an associated process. This study designs a methanol-electricity polygeneration system and presents a comprehensive discussion about the effects of the ratio of steam to coal, the ratio of O-2 to coal, the ratio of carrier gas (CO2) to coal and the CO2 concentration in methanol synthesis gas on different performance indicators. The results show that the steam/coal ratio has slight effects on the overall system performance due to the offset in different sections. An optimal O-2/coal ratio exists in the range of 0.84-0.86 to achieve the minimum unit water consumption and the maximum methanol production and energy efficiency, which is almost consistent with the range that the H-2 concentration in gasifier syngas reaches the maximum value. The amount of carrier gas CO2 and the CO2 concentration in methanol synthesis gas should be kept at a low level to just meet the requirements of coal pressurization and synthesis reaction. This comprehensive sensitivity analysis can provide some significant guidance for the system design.

关键词： Polygeneration Coal gasification H/C ratio adjustment Energy efficiency Water consumption

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