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Enhancing mixing of cohesive particles by baffles in a rotary drum

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Particuology 2016年第2期14卷 104-110页

作者： Zhixing zhou Jihong Li jingzhi zhou Shizhong Li Junxiao Feng Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Beijing Engineering Research Centre of Biofuels China MOST-USDA Joint Research Center for Biofuels Beijing 100084 China Department of Thermal Science an-d Energy Engineering School of Mechanical Engineering University of Science and Technology Beifing Beijing 100081 China

A soft-sphere discrete cohesive powder model was used to simulate the transverse mixing of particles in a rotary drum. Using this model, the effect of cohesion strength and baffle length was investigated. Mixing time （tR） and mixing entropy were used to characterize the mixing behavior. The results showed that increasing particle cohesiveness increases tR. Baffles enhanced transverse mixing, especially for high- cohesive particles. Moreover, the baffle length played a significant role on mixing. An optimized length of 0.50 （L/R） enhances transverse mixing for high-cohesive particles, Further increases in baffle length only decreases the mixing rate by impeding the surface flow layer. In contrast to high-cohesive particles, low-cohesive particles needed much shorter baffles.A soft-sphere discrete cohesive powder model was used to simulate the transverse mixing of particles in a rotary drum. Using this model, the effect of cohesion strength and baffle length was investigated. Mixing time （tR） and mixing entropy were used to characterize the mixing behavior. The results showed that increasing particle cohesiveness increases tR. Baffles enhanced transverse mixing, especially for high- cohesive particles. Moreover, the baffle length played a significant role on mixing. An optimized length of 0.50 （L/R） enhances transverse mixing for high-cohesive particles. Further increases in baffle length only decreases the mixing rate by impeding the surface flow layer. In contrast to high-cohesive particles, low-cohesive particles needed much shorter baffles.

关键词： Cohesive particles Mixing Baffles Rotary drum

A Comprehensive Review of Thermal Performance Improvement of High-Temperature Heat Pipes

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Journal of Thermal Science 2024年第2期33卷 625-647页

作者： CHEN Qihan zhou jingzhi zhou Guohui CHENG Keyong HUAI Xiulan WEI Gaosheng School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing100096China Nanjing Institute of Future Energy System Nanjing211135China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China

Energy efficiency issues are being focused on the growing concern of global warming and environmental *** high-temperature heat pipe(HTHP) is an effective and environmental-friendly heat transfer device employed in many industries,including solar power generation,high-temperature flue gas waste heat recovery,industrial furnaces,nuclear industries,and *** a critical factor in HTHPs,thermal performance is mainly introduced in the entire *** date,most reviews have been published concerning one or several application ***,to the best of authors' knowledge,it is hard to find a review discussing how to improve the thermal performance of HTHPs ***,the impact on the performance of three main components of HTHPs over the past 30 years is introduced:the working fluid,the HTHP structure,and the wick ***,it is a considerable review of the optimal operating conditions for each direction,and we expect this paper contribute to improving the thermal performance of ***,current numerical simulations and theoretical research on the heat transfer limit of HTHPs are *** significant hypotheses used in numerical simulations and the present theoretical studies are compiled ***,some potential future directions and tentative suggestions for HTHP research are put forward.

关键词： high-temperature heat pipe review alkali metal heat pipe thermal performance

Experimental and Numerical Study of an 80-kW Zigzag Printed Circuit Heat Exchanger for Supercritical CO_(2)Brayton Cycle

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Journal of Thermal Science 2021年第4期30卷 1289-1301页

作者： ZHANG Huzhong CHENG Keyong HUAI Xiulan zhou jingzhi GUO Jiangfeng Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

In this study,an experimental system was built to investigate the global performance of an 80-k W zigzag printed circuit heat exchanger(PCHE).It could meet the requirement of the pre-cooler for the supercritical carbon dioxide(S-CO_(2))Brayton power cycle and the modified effectiveness considering the pinch point is between 61.5%and 79.3%.When the outlet S-CO_(2)temperature is near the pseudo-critical point,the thermo-physical properties have more effects on heat transfer performance compared to flow *** the local performance,the mass flow rates of both sides have crucial influences on the location where the peak of S-CO_(2)Nusselt number occurs while only the S-CO_(2)flow rate affects the variation of the peak *** addition,the influence of the radius of curvature on the secondary-flow should not be *** the end,new empirical correlations were proposed considering the drastic variations of the Prandtl number.

关键词： Printed Circuit Heat Exchanger(PCHE) supercritical carbon dioxide(S-CO_(2)) pre-cooler zigzag channel thermal-hydraulic performance

Numerical study of collection efficiency and heat-transfer characteristics of packed granular filter

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Particuology 2019年第5期17卷 75-82页

作者： Junlin Chen Xunfeng Li Xiulan Huai Yongwei Wang jingzhi zhou Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

The collection mechanism and heat-transfer characteristics of a packed granular filter were investigated using a three-dimensional randomly packed granular filter model. The bridging method was introduced to optimize the grids of contact points between granules. The influences of granular bed depth, gas velocity, and gas temperature on grade collection efficiency were investigated. The results indicated that a decrease of temperature improved collection efficiency when the particle diameter was greater than 5 |xm. The grade collection efficiency maintained a stable value when the Stokes number, St, was less than 0.009, but increased linearly with ig(St) when St > 0.009. A logarithmic mean temperature difference method was used to obtain overall heat-transfer coefficients of gas-solid two-phase flow through the packed granular filter. The results showed that convective heat transfer was enhanced due to the intro-duction of solid particles in the bed. The overall heat-transfer coefficient increased approximately linearly with an increase in particle loading ratio. The Nusselt number was related to the Reynolds number, the Archimedes number, and the particle loading ratio.

关键词： Packed granular filter Gas-solid two-phase flow Grade collection efficiency Heat transfer

Synthesis and Characterization of Disodium Hydrogen Phosphate Dodecahydrate-Lauric-Palmitic Acid Used for Indoor Energy Storage Floor Units

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Journal of Thermal Science 2020年第2期29卷 477-485页

作者： XU Qian AKKURT Nevzat ZOU Zhenwei LIU Yang FENG Junxiao YU Chuqiao DING Chong XIONG Yaxuan zhou jingzhi ZANG Yong DING Yulong School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Department of Mechanical Engineering Munzur UniversityTunceli 62000Turkey School of Information and Electronics Communication and Information SystemBeijing Institute of TechnologyBeijing 100081China School of Mathematics Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of HVAC Beijing University of Civil Engineering and ArchitectureBeijing 100044China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China

Organic and inorganic phase change materials(PCMs) are considered potential materials for thermal energy storage(TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material(PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid(D-LA-PACM) was prepared. Expanded graphite(EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the microstructure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6℃ and 34.3℃ and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid(LA-PA) and disodium hydrogen phosphate dodecahydrate(DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(m·K). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.

关键词： organic-inorganic PCM form-stable PCM thermal property energy storage

HF-VHF dual-channel multifunctional radio astronomy terminal system

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Astronomical Techniques and Instruments 2024年第2期1卷 140-149页

作者： Kaijing Liu Liang Dong Huanhuan Xie Baoxin Li jingzhi zhou School of Information Engineering Southwest University of Science and TechnologyMianyang 621010China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Xi’an Research Institute of Navigation Technology Xi’an 710068China Yunnan Province China-Malaysia HF-VHF Advanced Radio Astronomy Technology International Joint Laboratory Kunming 650216China

The high frequency-very high frequency(HF-VHF)frequency band is of significant importance in astronomical observations,with applications studying various phenomena such as space weather,solar radio emissions,planetary eruptions in the solar system,pulsars,transient sources,and reionization of the early *** article introduces the HF-VHF frequency band multifunctional radio astronomical terminal system based on a dual-channel high-speed acquisition board with a frequency observation range of 1-250 MHz and a sampling rate of 500 Msps(Mega samples per second).The maximum quantization bit of the system is 14 bits,with a maximum time resolution of 0.1 s and a maximum spectral resolution of 16 *** system combines spectral analysis of solar radio signals and recording of time-domain data of signals interfering with long baselines,and adopts a server-client separation mode to allow remote operation with separate *** is used in the China-Malaysia joint astronomy project,which can carry out single-site observation of solar radio signals as well as interferometric observation of signals from multiple sites.

关键词： HF-VHF Solar radio High-speed acquisition Frequency domain analysis Time-domain recording.

高师转型为综合大学图书馆信息资源建设的思考

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图书情报工作 2008年第8期52卷 144-147页

作者：周敬治鲁东大学图书馆烟台264025

分析高等师范院校转型为地方综合大学后,随着自身战略定位的转变,图书馆信息资源建设定位、发展目标所发生改变,着重从转型后综合大学的教学、科研、重点学科、新上学科、师范特色、地方特色、自建专题数据库、学科导航库、特色数据库... 详细信息

分析高等师范院校转型为地方综合大学后,随着自身战略定位的转变,图书馆信息资源建设定位、发展目标所发生改变,着重从转型后综合大学的教学、科研、重点学科、新上学科、师范特色、地方特色、自建专题数据库、学科导航库、特色数据库等方面,阐述地方综合大学图书馆的信息资源建设。

关键词：综合大学图书馆信息资源

发酵秸秆碎料内乙醇平面热源法提取及其设备设计

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农业机械学报 2018年第5期49卷 330-341页

作者：周敬之冯俊小北京科技大学能源与环境工程学院北京100083 冶金工业节能减排北京市重点实验室北京100083

为降低固态发酵后秸秆碎料料内乙醇提取能耗,用平面热源进行乙醇提取并设计相应设备,进行初步计算。基于热重试验,研究了固态发酵后的甜高粱秆粉碎料中乙醇的蒸馏规律。考虑料含湿量、湿分乙醇体积分数、加热温度对料中湿分质量变化速... 详细信息

为降低固态发酵后秸秆碎料料内乙醇提取能耗,用平面热源进行乙醇提取并设计相应设备,进行初步计算。基于热重试验,研究了固态发酵后的甜高粱秆粉碎料中乙醇的蒸馏规律。考虑料含湿量、湿分乙醇体积分数、加热温度对料中湿分质量变化速率的影响,得出在研究范围内(含湿量10%~90%,湿分乙醇体积分数3%~11%,加热温度20~100℃)料中湿分质量变化速率与乙醇体积分数关系不大,随料含湿量呈线性关系,随加热温度呈幂函数关系,并得出回归模型。基于乙醇挥发数据,得出乙醇挥发数学模型。基于以上两模型,推导出平面热源提取乙醇的乙醇提取率方程,根据加热温度、料含湿量和湿分乙醇体积分数,便可计算任意时刻的乙醇提取率。建立成本模型并进行成本分析发现,该提取方法成本显著低于原有蒸汽提醇法。最后设计了一套采用平面热源连续提取发酵料内乙醇的生产装置,给出其设计计算式,进行了初步设计,得到一套示例性质的工业级设备方案。

关键词：秸秆碎料乙醇提取平面热源固态发酵装备设计

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立式镁还原罐还原过程中结构传热特性分析

化工进展 2018年第2期37卷 459-467页

作者：徐钱冯俊小周敬之北京科技大学能源与环境工程学院北京100083

为解决镁还原罐耗损大、寿命短的问题,本文根据国内外金属镁的还原工艺现状,综合考虑了温度、固定端数、罐长和罐厚对立式镁还原罐承载能力的影响,采用ANSYS有限元软件对立式镁还原竖罐的结构特性进行热力耦合模拟,得到还原系统应力场... 详细信息

为解决镁还原罐耗损大、寿命短的问题,本文根据国内外金属镁的还原工艺现状,综合考虑了温度、固定端数、罐长和罐厚对立式镁还原罐承载能力的影响,采用ANSYS有限元软件对立式镁还原竖罐的结构特性进行热力耦合模拟,得到还原系统应力场以及罐体温度场等,并对还原罐屈曲应力极限进行了研究,优化了还原罐的结构特征。同时考虑装料量对罐体强度的影响,研究装料量与还原罐温度场、还原罐屈曲应力极限之间的规律,对还原罐结构进一步优化。结果表明:物料层的导热和还原反应吸热使得物料中心与物料边缘处的升温速度有较大差距;增加中心管可适当减少镁罐的还原周期,且对镁还原反应的影响不大;高温载荷可导致还原罐屈曲应力大幅度降低(20%以上),对变形量影响较小,因此应尽量降低还原罐的工作温度。

关键词：传热立式镁还原罐有限元分析屈曲应力优化