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New insights into the deposition of natural gas hydrate on pipeline surfaces:A molecular dynamics simulation study

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Petroleum Science 2024年第1期21卷 694-704页

作者： Jun Zhang Hai-Qiang Fu Mu-Zhi Guo Zhao Wang Li-Wen Li Qi Yin You-Guo Yan Wei Wei Wei-Feng Han Jie Zhong School of Materials Science and Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina Department of Alternative Energy PetroChina Research Institute of Petroleum Exploration&DevelopmentLangfang 065007HebeiChina

Natural gas hydrate(NGH)can cause pipeline blockages during the transportation of oil and gas under high pressures and low temperatures.Reducing hydrate adhesion on pipelines is viewed as an efficient way to prevent NGH blockages.Previous studies suggested the water film can greatly increase hydrate adhesion in gas-dominant system.Herein,by performing the molecular dynamics simulations,we find in water-dominant system,the water film plays different roles in hydrate deposition on Fe and its corrosion surfaces.Specifically,due to the strong affinity of water on Fe surface,the deposited hydrate cannot convert the adsorbed water into hydrate,thus,a water film exists.As water affinities decrease(Fe>Fe_(2)O_(3)>FeO>Fe_(3)O_(4)),adsorbed water would convert to amorphous hydrate on Fe_(2)O_(3)and form the ordered hydrate on FeO and Fe_(3)O_(4)after hydrate deposition.While absorbed water film converts to amorphous or to hydrate,the adhesion strength of hydrate continuously increases(Fedeposition mechanisms on Fe and its corrosion surfaces and suggest hydrate deposition can be adjusted by changing water affinities on pipeline surfaces.

关键词： deposition Natural gas hydrate Pipelines Water affinity Adhesion strength

A progress review of black carbon deposition on Arctic snow and ice and its impact on climate change

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Advances in Polar Science 2024年第2期35卷 178-191页

作者： ZHANG Zilu ZHOU Libo ZHANG Meigen Department of Lower Atmosphere Observation Research(LAOR) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

The rapid warming of the Arctic,accompanied by glacier and sea ice melt,has significant consequences for the Earth’s climate,ecosystems,and economy.Black carbon(BC)deposition on snow and ice can trigger a significant reduction in snow albedo and accelerate melting of snow and ice in the Arctic.By reviewing the published literatures over the past decades,this work provides an overview of the progress in both the measurement and modeling of BC deposition and its impact on Arctic climate change.In summary,the maximum value of BC deposition appears in the western Russian Arctic(26 ng·g^(–1)),and the minimum value appears in Greenland(3 ng·g^(–1)).BC records in the Arctic ice core already peaked in 1920s and 1970s,and shows a regional difference between Greenland and Canadian Arctic.The different temporal variations of Arctic BC ice core records in different regions are closely related to the large variability of BC emissions and transportation processes across the Arctic region.Model simulations usually underestimate the concentration of BC in snow and ice by 2–3 times,and cannot accurately reflect the seasonal and regional changes in BC deposition.Wet deposition is the main removal mechanism of BC in the Arctic,and observations show different seasonal variations in BC wet deposition in Ny-Ålesund and Barrow.This discrepancy may result from varying contributions of anthropogenic and biomass burning(BB)emissions,given the strong influence by BC from BB emissions at Barrow.Arctic BC deposition significantly influences regional climate change in the Arctic,increasing fire activities in the Arctic have made BB source of Arctic BC more crucial.On average,BC in Arctic snow and ice causes an increase of+0.17 W·m^(–2)in radiative forcing and 8 Gt·a^(–1)in runoff in Greenland.As stressed in the latest Arctic Monitoring and Assessment Programme report,reliable source information and long-term and high-resolution observations on Arctic BC deposition will be crucial for a more comprehensive understanding and a better mitigation

关键词： Arctic climate black carbon albedo snow deposition

Relationship between hydrogenation degree and pyrolysis performance of jet fuel

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Chinese Journal of Chemical Engineering 2024年第4期68卷 35-42页

作者： Qing Liu Tinghao Jia Lun Pan Jijun Zou Xiangwen Zhang Key Laboratory for Green Chemical and Technology School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China Zhejiang Institute of Tianjin University Ningbo 315201China Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027China

Understanding the relationship between the chemical composition and pyrolysis performance of endothermic hydrocarbon fuel(EHF)is of great significance for the design and optimization of advanced EHFs.In this work,the effect of deep hydrogenation on the pyrolysis of commercial RP-3 is investigated.Fuels with different hydrogenation degrees were obtained by the partially and completely catalytic hydrogenation and their pyrolysis performances were investigated using an apparatus equipped with an electrically heated tubular reactor.The results show that with the increase of hydrogenation degree,fuel conversion almost remains constant during the pyrolysis process(500e650C,4 MPa);however,the heat sink increases slightly,and the anti-coking performance significantly improves,which are highly related to their H/C ratios.Detailed characterisations reveal that the difference of the pyrolysis performance can be ascribed to the content of aromatics and cycloalkanes:the former are prone to initiate secondary reactions to form coking precursors,while the latter could act as the hydrogen donor and release hydrogen,which will terminate the radical propagation reactions and suppress the coke deposition.This work should provide the guidance for upgrading EHFs by modulating the composition of EHFs.

关键词： RP-3 Fuel Pyrolysis Hydrogenation deposition

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Tracing the origin of large respiratory droplets by their deposition characteristics inside the respiratory tract during speech

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Building Simulation 2023年第5期16卷 781-794页

作者： Yihan Wang Jianjian Wei Caroline X.Gao Tao Jin Li Liu Institute of Refrigeration and Cryogenics Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang ProvinceZhejiang UniversityHangzhou 310000China Public Health and Preventive Medicine Monash UniversityMelbourneVIC3004Australia Department of Building Science Tsinghua UniversityBeijing 100084China

Origin of differently sized respiratory droplets is fundamental for clarifying their viral loads and the sequential transmission mechanism of SARS-CoV-2 in indoor environments.Transient talking activities characterized by low(0.2 L/s),medium(0.9 L/s),and high(1.6 L/s)airflow rates of monosyllabic and successive syllabic vocalizations were investigated by computational fluid dynamics(CFD)simulations based on a real human airway model.SST k-ωmodel was chosen to predict the airflow field,and the discrete phase model(DPM)was used to calculate the trajectories of droplets within the respiratory tract.The results showed that flow field in the respiratory tract during speech is characterized by a significant laryngeal jet,and bronchi,larynx,and pharynx-larynx junction were main deposition sites for droplets released from the lower respiratory tract or around the vocal cords,and among which,over 90%of droplets over 5μm released from vocal cords deposited at the larynx and pharynx-larynx junction.Generally,droplets’deposition fraction increased with their size,and the maximum size of droplets that were able to escape into external environment decreased with the airflow rate.This threshold size for droplets released from the vocal folds was 10-20μm,while that for droplets released from the bronchi was 5-20μm under various airflow rates.Besides,successive syllables pronounced at low airflow rates promoted the escape of small droplets,but do not significantly affect the droplet threshold diameter.This study indicates that droplets larger than 20μm may entirely originate from the oral cavity,where viral loads are lower;it provides a reference for evaluating the relative importance of large-droplet spray and airborne transmission route of COVID-19 and other respiratory infections.

关键词： respiratory droplets deposition viral load airborne transmission COVID-19

deposition law of flat fan nozzle for pesticide application in horticultural plants

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International Journal of Agricultural and Biological Engineering 2022年第4期15卷 27-38页

作者： Xiaoyi Wu Yalan Jia Bo Luo Chongchong Chen Yaxiong Wang Feng Kang Jiale Li School of Technology Beijing Forestry UniversityKey Lab of State Forestry Administration for Forestry Equipment and AutomationBeijing100083China Army Aviation Institute Beijing 101123China

Pesticide spraying is to protect the plants with adequate target coverage and a minimum of off-target drift.Understanding the spatial distribution characteristics of spray droplets is essential for regulating pesticide deposition,in order to investigate the relationship between the two at the mechanistic level and provide an accurate basis for nozzle selection,this study compared the characteristics of the atomization field under different pressures,angles,and flow rate types by phase Doppler particle analyzer(PDPA),the unit spatial density of droplet was used as a link to explore the internal mechanism that affects the deposition efficiency by constructing a transport model and conducting actual spraying experiments.The results showed that the cumulative distribution of droplet diameter could be perfectly fitted by the Rosin-Rammler correlation,and the deposition efficiency had a strong correlation with the peak particle size range.For strawberry and chrysanthemum plants,the optimal droplet deposition particle size ranges were 250-270μm and 240-260μm,respectively.This article explained the deposition efficiency from a single droplet dynamics mechanism and deposition of droplet cloud,which provided a new research idea for the study of precision plant protection.

关键词： pesticide transport deposition atomization field PDPA

Modeling study on the roles of the deposition and transport of PM_(2.5) in air quality changes over central-eastern China

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Journal of Environmental Sciences 2023年第1期123卷 535-544页

作者： Lei Zhang Jianjun He Sunling Gong Xiaomei Guo Tianliang Zhao Huizheng Che Hong Wang Chunhong Zhou Jingyue Mo Ke Gui Yu Zheng Lei Li Junting Zhong Xiaoye Zhang State Key Laboratory of Severe Weather&Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological SciencesBeijing 100081China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Chengdu 610072China Weather Modification Office of Sichuan Province Chengdu 610072China Climate and Weather Disasters Collaborative Innovation Center Nanjing University of Information Science&TechnologyNanjing 210044China

The role of PM_(2.5)(particles with aerodynamic diameters≤_(2.5)μm)deposition in air quality changes over China remains unclear.By using the three-year(2013,2015,and 2017)simulation results of the WRF/CUACE v1.0 model from a previous work(Zhang et al.,2021),a non-linear relationship between the deposition of PM_(2.5)and anthropogenic emissions over central-eastern China in cold seasons as well as in different life stages of haze events was unraveled.PM_(2.5)deposition is spatially distributed differently from PM_(2.5)concentrations and anthropogenic emissions over China.The North China Plain(NCP)is typically characterized by higher anthropogenic emissions compared to southern China,such as the middlelow reaches of Yangtze River(MLYR),which includes parts of the Yangtze River Delta and the Midwest.However,PM_(2.5)deposition in the NCP is significantly lower than that in the MLYR region,suggesting that in addition to meteorology and emissions,lower deposition is another important factor in the increase in haze levels.Regional transport of pollution in central-eastern China acts as a moderator of pollution levels in different regions,for example by bringing pollution from the NCP to the MLYR region in cold seasons.It was found that in typical haze events the deposition flux of PM_(2.5)during the removal stages is substantially higher than that in accumulation stages,with most of the PM_(2.5)being transported southward and deposited to the MLYR and Sichuan Basin region,corresponding to a latitude range of about 24°N-31°N.

关键词： PM_(2.5) deposition Regional transport China WRF/CUACE v1.0 model

Effect of existence state of asphaltenes on the asphaltenes-wax interaction in wax deposition

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Petroleum Science 2023年第1期20卷 507-514页

作者： Yun Lei Han Wang Shuang-Shuang Li Xue-Qian Liu Hao-Ran Zhu Yu-Ming Gao Hao-Ping Peng Peng-Fei Yu Jiangsu Key Laboratory of Oil and Gas Storage&Transportation Technology Changzhou UniversityJiangsu213164China

Asphaltenes are the most elusive substances in waxy crude oil,especially the complex structures,which leads to significant precipitation and aggregation characteristics of asphaltenes,and affects the asphaltenes-wax interaction.In this study,the concept of the existence state of asphaltenes was introduced to semi-quantitatively investigate the precipitation and aggregation characteristics of asphaltenes.On this basis,the influence of the existence state of asphaltenes on wax deposition was studied by coldfinger device and high-temperature gas chromatography,and the composition and properties of the deposits were analyzed.Four main findings were made:(1)As the asphaltene concentration increases,the existence state of asphaltenes gradually transitions from dispersed state to aggregated state,and the asphaltene concentration of 0.30 wt%in this study is the starting point of the transition.(2)The existence state of asphaltenes in crude oil does affect the process of wax deposition,as shown in the fact that the dispersed asphaltenes promote the occurrence of wax deposition,while the aggregated asphaltenes can inhibit wax deposition.(3)In the presence of the aggregated asphaltenes,that is,when the asphaltene concentration is higher than 0.30 wt%,the shedding phenomenon of deposit layer was observed,and with the increase of aggregated asphaltenes,the deposit layer fell off earlier.(4)With the increase of the dispersed asphaltenes,the wax appearance temperature(WAT)and wax content of the deposits all showed an increasing trend,while with the appearance of the aggregated asphaltenes,the above situation was reversed.The findings of this study can help for better understanding of the interaction between the asphaltenes and wax in wax deposition.

关键词： Asphaltenes Precipitation/aggregation Existence state of asphaltenes deposition

Molecular sieve based Janus separators for Li-ions redistribution to enable stable lithium deposition

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Nano Research 2022年第6期15卷 5143-5152页

作者： Huanyu Xie Zhimeng Hao Shuai Xie Yadong Ye Wei Zhang Zhaowei Sun Song Jin Hengxing Ji Jun Chen Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Materials for Energy ConversionDepartment of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) College of ChemistryNankai UniversityTianjin 300071China

During operation of a lithium metal battery,uneven lithium deposition often results in the growth of lithium dendrites and causes a rapid decay in battery performance and even leads to safety issues.This is still the main hurdle hindering the practical application of lithium metal anodes.We report a new type of Janus separator fabricated by introducing a molecular sieve coating on the surface of the polypropylene separator that serves as a redistribution layer for lithium ions.Our results show that using this layer,the growth of lithium dendrites can be largely inhibited and the battery performance greatly improved.In a typical Li||Cu half-cell with the Janus separator,the Coulombic efficiency of the lithium metal anode can be maintained at>98.5%for over 500 cycles.The cycling life span is also extended by a factor of 8 in the Li||Li symmetric cell.Furthermore,the high-strength coating improves the mechanical properties of the separator,thus enhancing safety.The effectiveness of our strategy is demonstrated by both the inhibited growth of lithium dendrites and the improved battery performance.Our methodology could eventually be generalized for electrode protection in other battery systems.

关键词： Janus separator molecular sieve redistribution lithium metal anode deposition

Chemical Determination of Base Status Metals in Soil Sediments and Particulate Matter in Wellington Industrial Estate Location

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Open Journal of Applied Sciences 2024年第5期14卷 1338-1352页

作者： Richard Tamba Simbo Jerry Yeke Paye Fayia Francis Nyuma Department of Chemistry School of Basic Sciences Njala University Freetown Sierra Leone Department of Science and Mathematics College of Arts and Sciences William V.S. Tubman University Harper Liberia Department of Fisheries and Science Thomas J.R Faulkner College of Science and Technology University of Liberia Monrovia Liberia

This research study explored the levels of base status metals in soil sediments and particulate matter in the wellington industrial estate location;the main objectives were to: 1) determine sodium and potassium, 2) determine calcium and magnesium, 3) determine available iron. The following hypotheses were put forward;H0a: there is no significant difference in the concentration levels between Ca and Mg in the study area, H1a: there is significant difference in the concentration levels between Ca and Mg in the study area, H0b: there is no significant difference in the concentration levels between Na and K in the study area, H1b: there is significant difference in the concentration levels between Na and K in the study area. Six locations were used to collect samples with the aid of scoop and gravel free auger (at varying depths of 0 - 5 cm and 5 - 10 cm) which are Wellington Industrial Estate Area 1 (WIEL 1), (WIEL 2), (WIEL 3), (WIEL 4), (WIEL 5), (WIEL 6);the samples were given laboratory treatment. Flame photometer, EDTA, and Spectrophotometer were used in the determinations of sodium and potassium, calcium and magnesium, and available iron respectively. The results indicated that levels of potassium were in medium range (moderately high);sodium levels were generally low when compared to Brook’s classification table. Levels of calcium were generally low and those of magnesium were moderate based on Brook’s table of classification. Levels of available iron which fall within the range of Quijano-Guerta (2003) were high;this implies such levels can lead to toxicity. In all locations, there was decrease in the levels of each metal in the samples with (5 - 10 cm) depth.

关键词： deposition Environment Particulate Sediment Toxicity