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Mixed convective heat transfer characteristics and mechanisms in structured packed beds

Particuology 2023年第11期82卷 122-133页

作者： Yuelong Qu Liang Wang Xipeng Lin Haisheng Chen Shuang Zhang Haoshu Ling yakai bai Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalian116023China

The structured packed bed is considered a promising reactor owing to its low pressure drop and good heat transfer *** the heat transfer process of thermal storage in packed beds,natural convection plays an important *** obtain the mixed convective heat transfer characteristics and mechanisms in packed beds,numerical simulations and coupling analyses were carried out in this study on the unsteady process of fluid flow and heat transfer.A three-dimensional model of the flow channel in the packed bed was established,and the Navier–Stokes equations and Laminar model were adopted for the *** effects of the driving force on fluid flow around a particle were studied in *** differences in velocity and density distributions under different flow directions due to effect of the aiding flow or opposing flow were intuitively demonstrated and quantitatively *** was found that the driving force strengthens the fluid flow near the particle surface when aiding flow occurs and inhibits the fluid flow when opposing flow *** boundary layer structure was changed by the natural convection,which in turn influences the field synergy *** the aiding flow,the coordination between the velocity and density fields is higher than that for the opposing *** analysis the effects of physical parameters on mixed convective heat transfer,it is indicated that with an increase in the fluid-solid temperature difference or the particle diameter,or a decrease in the fluid temperature,the strengthening or inhibiting effect of natural convection on the heat transfer became more significant.

关键词： Computational fluiddynamics Packed beds Natural convection Heat transfer

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Influence of geometry on the thermal performance of water pit seasonal heat storages for solar district heating

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Building Simulation 2021年第3期14卷 579-599页

作者： yakai bai Ming Yang Jianhua Fan Xiaoxia Li Longfei Chen Guofeng Yuan Zhifeng Wang Key Laboratory of Solar Thermal Energy and Photovoltaic Systems Chinese Academy of SciencesBeijing 700190China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Civil Engineering Technical University of DenmarkBrovej 1182800 Kgs.LyngbyDenmark Joint Laboratory Institute of Electrical EngineeringChinese Academy of Sciences and Guangdong Five Star Solar Energy Co.Ltd.Beijing 100190China Lanzhou University of Technology Gansu 730050China

The aim of the study is to investigate the influence of geometry on the thermal capacity and stratifications of a water pit heat storage for solar district heating.A TRNSYS component model for a truncated cone water pit was developed based on the coordinate transformation method and validated by experimental results from the water pit heat storage in Huangdicheng in *** thermal performance of 26 water pits with different heights and side wall slopes was calculated for 10 consecutive *** takes four to six years for the water pit to reach steady-state *** operation data from the tenth year was selected to evaluate the thermal performance of each *** results show that because of the thermal insulation on top of the water pit,the height to diameter ratio of a water pit with minimum annual heat loss was always smaller than *** annual storage efficiency of a water pit increases with side wall slope due to the reduced side wall *** is an almost linear increase in the thermal stratification number of a water pit with *** an increase in the height,thermal stratification in water pits with a steeper slope increased more gradually than water pits with a lower *** findings in this paper are relevant for the design optimization of water pits as seasonal thermal energy storages.

关键词： water pit seasonal heat storage truncated cone storage capacity thermal stratification coordinate transformation

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Thermal Analysis of a Volumetric Solar Receiver

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Journal of Thermal Science 2019年第6期28卷 1176-1185页

作者： CHEN Longfei YANG Ming LI Jinping bai yakai LI Xiaoxia TANG Wenxue YANG Nancong WANG Zhifeng Lanzhou University of Technology Lanzhou 730050China Key Laboratory of Solar Thermal Energy and Photovoltaic Systems Chinese Academy of SciencesBeijing 100190China Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Beijing Engineering Research Center of Solar Thermal Power Beijing 100190China Beijing CSP International Cooperation Centre Beijing 100190China Joint Laboratory Institute of Electrical EngineeringChinese Academy of Sciences and Guangdong Five Star Solar Energy Co.Ltd.Beijing 100190China Guangdong 5 Star Solar Energy CO.LTD Dongguan 523051China

The volumetric receiver has received wide attention due to its high thermal efficiency. This paper studied a new type of a solid-liquid composite volumetric receiver. The heat transfer in a solid-liquid composite volumetric solar receiver was analyzed using a one-dimensional unsteady simulation model of the solid-liquid receiver. The model included absorption of the incident solar radiation by the glass window, the silicon carbide porous ceramic heat absorber panel and the water. The results were verified against experimental data for a volumetric receiver and the error did not exceed 10%. It can be used to predict the heat transfer in solid-liquid composite volumetric receivers.

关键词： solar receiver solid-liquid composite absorber silicon carbide porous ceramic volumetric solar collector

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基于圆柱封装单元的水合盐相变储热填充床的储释特性实验研究

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储能科学与技术 2024年第8期13卷 2623-2633页

作者：刘云汉王亮张双林曦鹏葛志伟白亚开林霖王艺斐陈海生华北电力大学能源动力与机械工程学院北京102206 中国科学院工程热物理研究所北京100190 中国科学院大学北京100049 毕节高新技术产业开发区国家能源大规模物理储能技术研发中心贵州毕节551700

水合盐相变储热技术具有储热密度高、成本低等优势,在清洁供暖中具有广阔应用前景。本研究设计并搭建了以三水合乙酸钠作为储热材料,以圆柱形相变材料封装单元作为基础单元的填充床相变储热装置。通过实验研究填充床储热装置的运行特性... 详细信息

水合盐相变储热技术具有储热密度高、成本低等优势,在清洁供暖中具有广阔应用前景。本研究设计并搭建了以三水合乙酸钠作为储热材料,以圆柱形相变材料封装单元作为基础单元的填充床相变储热装置。通过实验研究填充床储热装置的运行特性,研究了流量和储热温度对装置的储释热用时、出口温度、热效率及储热密度的影响。实验结果表明:提高储热温度和增大流量可缩短储热用时、提升热效率和储热密度。储热装置的热效率可达94.73%,储能密度可达71.77 kW·h/m^(3)。

关键词：无机水合盐相变材料储热装置填充床

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Polyethylenimine-modified graphene quantum dots promote endothelial cell proliferation

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Regenerative Biomaterials 2024年第2期3卷 137-146页

作者： Qirong Xu Chen Li Xiangyan Meng Xinghong Duo yakai Feng School of Chemistry and Chemical Engineering Qinghai University for NationalitiesXining 810007PR China Key Laboratory of National Ethnic Affairs Commission of Resource Chemistry and Ecological Environment Protection on Qinghai-Tibet Plateau Xining 810007PR China institute of Disaster and Emergency Medicine Tianjin UniversityTianjin 300072PR China School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350PR China Key Laboratory of Systems Bioengineering(Ministry of Education) Tianjin UniversityTianjin 300072PR China

Endothelial cell proliferation plays an important role in angiogenesis and treatment of related *** aim of this study was to evaluate the effect of polyethylenimine(PEI)-modified graphene quantum dots(GQDs)gene vectors on endothelial cell *** GQDs-cationic polymer gene vectors were synthesized by amidation reaction,and used to deliver pzNF580 gene to Human umbilical vein endothelial cells(HUVECs)for promoting their *** chemical modification of GQDs can ad-just gene vectors'surface properties and charge distribution,thereby enhancing their interaction with gene molecules,which could effectively compress the pZNF580 *** CCK-8 assay showed that the cell viability was higher than 80%at higher vector concentration(40μg/mL),demonstrating that the GQDs-cationic polymer gene vectors and their gene complex nanoparticles(NPs)having low *** results of the live/dead cell double staining assay were consistent with those of the CCK-8 assay,in which the cell viability of the A-GQDs/pZNF580(94.38±6.39%),C-GQDs-PEI-polylactic acid-co-polyacetic acid(PLGA)/pZNF580(98.65±6.60%)and N-GQDs-PEI-PLGA/pZNF580(90.08±1.60%)groups was significantly higher than that of the Lipofectamine 2000/pzNF580(71.98±3.53%)positive treatment *** results of transfection and western blot experiments showed that the vector significantly enhanced the delivery of plasmid to HUVECs and increased the expression of pZNF580 in *** addition,the gene NPs better promote endothelial cell migration and *** cell migration rate and proliferation ability of C-GQDs-PEI-PLGA/pZNF580 and N-GQDs-PEI-PLGA/pZNF580 treatment groupS were higher than those of Lipofectamine 2000/pDNA treatment *** GQDs possess the potential to serve as efficient gene *** tightly bind gene molecules through charge and other non-covalent interactions,significantly improving the effciency of gene delivery and ensuring the smooth release of genes with

关键词： graphene quantum dots polyethylenimine ZNF580 gene endothelial cell proliferation

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超声波辅助加工技术应用综述

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中国铸造装备与技术 2024年第3期59卷 38-42页

作者：刘国强白雅凯李文振张玉宋宪涛张彦李武秀吴凡董德骁安业龙山东省机械设计研究院山东济南250031 齐鲁工业大学(山东省科学院) 机械工程学院山东济南250301 枣庄市瑞隆机械制造有限公司山东枣庄277400 济南和谐模具制造有限公司山东济南251400 山东承泽金属科技有限公司山东德州251100

材料加工历史悠久,目前呈现出精益、高效、高质量、绿色环保的发展趋势。其中,超声波辅助加工技术在优化材料性能、提升表面质量和结构精准控制等方面,起到有益的作用。从超声波辅助加工角度探讨了超声波辅助焊接、增材制造、激光熔覆... 详细信息

材料加工历史悠久,目前呈现出精益、高效、高质量、绿色环保的发展趋势。其中,超声波辅助加工技术在优化材料性能、提升表面质量和结构精准控制等方面,起到有益的作用。从超声波辅助加工角度探讨了超声波辅助焊接、增材制造、激光熔覆、先进材料制备、残余应力检测及去除等不同场景中的应用,并总结了超声波辅助加工的技术特点及发展趋势。

关键词：材料加工超声波辅助加工激光熔覆先进材料制备

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Spatial-temporal differentiation and influencing factors of rural settlements in mountainous areas: an example of Liangshan Yi Autonomous Prefecture, Southwestern China

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Journal of Mountain Science 2024年第1期21卷 218-235页

作者： WANG Yumeng DENG Qingchun YANG Haiqing LIU Hui YANG Feng ZHAO yakai School of Geographical Sciences China West Normal UniversityNanchong 637009China Sichuan Provincial Engineering Laboratory of Monitoring and Control for Soil Erosion in Dry Valleys China West Normal UniversityNanchong 637009China Liangshan Soil Erosion and Ecological Restoration in Dry Valleys Observation and Research Station Xide 616753China

Rural settlement is the basic spatial unit for compact communities in rural area. Scientific exploration of spatial-temporal differentiation and its influencing factors is the premise of spatial layout rationalization. Based on land use data of Liangshan Yi Autonomous Prefecture(hereinafter referred to as Liangshan Prefecture) in Sichuan Province, China from 1980 to 2020, compactness index, fractal dimension, imbalance index, location entropy and the optimal parameters-based geographical detector(OPGD) model are used to analyze the spatial-temporal evolution of the morphological characteristics of rural settlements, and to explore the influence of natural geographical factors, socioeconomic factors, and policy factors on the spatial differentiation of rural settlements. The results show that:(1) From 1980 to 2020, the rural settlements area in Liangshan Prefecture increased by 15.96 km^(2). In space, the rural settlements are generally distributed in a local aggregation, dense in the middle and sparse around the periphery. In 2015, the spatial density and expansion index of rural settlements reached the peak.(2) From 1980 to 2020, the compactness index decreased from 0.7636 to 0.7496, the fractal dimension increased from 1.0283 to 1.0314, and the fragmentation index decreased from 0.1183 to 0.1047. The spatial morphological structure of rural settlements tended to be loose, the shape contour tended to be complex, the degree of fragmentation decreased, and the spatial distribution was significantly imbalanced.(3) The results of OPGD detection in 2015 show that the influence of each factor is slope(0.2371) > traffic accessibility(0.2098) > population(0.1403) > regional GDP(0.1325) > elevation(0.0987) > poverty alleviation(0). The results of OPGD detection in 2020 show that the influence of each factor is slope(0.2339) > traffic accessibility(0.2198) > population(0.1432) > regional GDP(0.1219) > poverty alleviation(0.0992) > elevation(0.093). Natural geographical facto

关键词： Rural settlements Location entropy Geographical detector Spatiotemporal differentiation Influencing factors

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基于技术经济学的氨水脱碳工艺参数影响分析

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动力工程学报 2016年第7期36卷 541-550页

作者：韩中合白亚开华北电力大学电站设备状态监测与控制教育部重点实验室河北保定071003

为了合理评价氨水脱碳工艺与燃煤电厂集成后的运行性能,基于脱碳系统仿真模型和燃煤电厂变工况模型,利用技术经济学方法建立了脱碳机组评价体系.考察了CO_2捕集系统主要参数(氨水质量分数、贫液CO_2负荷、吸收塔入口温度、再生塔压力、... 详细信息

为了合理评价氨水脱碳工艺与燃煤电厂集成后的运行性能,基于脱碳系统仿真模型和燃煤电厂变工况模型,利用技术经济学方法建立了脱碳机组评价体系.考察了CO_2捕集系统主要参数(氨水质量分数、贫液CO_2负荷、吸收塔入口温度、再生塔压力、氨气逃逸率和CO_2捕集率)对机组运行性能的影响,选取了氨水脱碳系统可行运行参数.结果表明:氨水质量分数为11%、贫液负荷为0.36以及吸收塔入口温度为15℃为该系统可行运行参数,此时脱碳机组相对于优化前发电效率提升了0.712 7%,发电煤耗降低了6.959 4g/(kW·h),发电成本降低了0.011元/(kW·h),脱碳成本降低了16.756 3元/t.

关键词：冷冻氨法二氧化碳发电成本脱碳成本

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A novel reprocessable chloroprene rubber based on dynamic disulfide metathesis

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International Journal of Smart and Nano Materials 2024年第1期15卷 42-61页

作者： Jianliang Jiang Junxue Zhai Yanqing Chen Dongqi Zhao yakai Feng School of Chemical Engineering and Technology Collaborative Innovation Center of Chemical Science and Chemical Engineering(Tianjin)Tianjin UniversityTianjinChina R&D Department of China(Yangzhou) Material Handling Tech-Engineering LtdYangzhouChina Key Laboratory of Rubber Plastics of Ministry of Education/Shandong Province (QUsT)School of Polymer Science&EngineeringQingdao University of Science&TechnologyQingdaoChina R&D Department of Tianjin Joaboa Technology Co.Ltd TianjinP.R.China Frontiers Science Center for Synthetic Biology Tianjin UniversityTianjinChina Key Laboratory of Systems Bioengineering(Ministry of Education) Tianjin UniversityTianjinChina

For sustainable application of chloroprene rubber(CR),a new technology is developed by the vulcanization of CR using 2,2'-dithiodipyridine(DPD)as a cross-linking agent with the repro-cessing performance owing to disulfde *** DPD was incorporated into CR vulcanization,the Menschutkin reac-tion between allyl chloride group and pyridine group occurred with a maximum exothermic peak at 184°*** number of effective cross-linking bond at o.5 phr DPD vulcanizate was higher than that at high DPD *** vulcanizate showed high tensile strength(11.12 MPa)and elongation at break(1253±120%)owing to the exchangeable disulfide bond in the *** the catalysis of triphenylphosphine,the metathesis of disulfide compound was improved obviously,which endowed CR/DPD vulcanizates with good recyclability *** cross-linkage maintains its stability at low temperature,thus ensuring the mechanical stability of CR/DPD vulcanizate under the ambient *** and reprocessing of CR/DPD vulcanizate can be conducted with common industrial rubber processing *** reprocessable chloroprene rubber could have potential appli-cation in CR industry,also serve to significantly improve envir-onmental sustainability.

关键词： Chloroprene rubber reprocessable Menschutkin reaction disulfide

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镍基合金复合材料涂层研究现状

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中国铸造装备与技术 2024年第4期59卷 39-43页

作者：刘国强安业龙张玉李文振李武秀宋宪涛董德骁吴银龙王修涛周瑞白雅凯山东省机械设计研究院山东济南250031 齐鲁工业大学(山东省科学院)机械工程学院山东济南250301 枣庄市瑞隆机械制造有限公司山东枣庄277400 山东承泽金属科技有限公司山东德州251100 济南和谐模具制造有限公司山东济南251400

镍基合金复合材料涂层作为一种高性能表面防护材料,在海工、航空航天、能源、化工等领域具有广泛的应用前景。本文探讨了关于镍基合金的涂层熔覆技术,陶瓷材料复合涂层、高分子材料复合涂层、不同镍基合金涂层等技术特点。研究发现,通... 详细信息

镍基合金复合材料涂层作为一种高性能表面防护材料,在海工、航空航天、能源、化工等领域具有广泛的应用前景。本文探讨了关于镍基合金的涂层熔覆技术,陶瓷材料复合涂层、高分子材料复合涂层、不同镍基合金涂层等技术特点。研究发现,通过引入涂层可以提高镍基合金的硬度、耐腐蚀性、耐磨性,总结了镍基合金发展趋势。

关键词：镍基合金复合材料陶瓷材料复合涂层

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