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Collection efficiency in a three-dimensional randomly arranged dual-layer granular bed filter

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Particuology 2020年第2期18卷 88-94页

作者： Junlin Chen xunfeng li Xiulan Huai Jingzhi Zhou Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The dual-layer granular bed filter packed with randomly arranged granules was simulated to study the effects of bed depth of the lower layer of fine granules and the inlet gas velocity on the collection *** computational results show that the collection efficiency is much better from this granular bed than a single-layer granular bed,especially for particle diameters of 1-10μ*** inlet gas velocity has less effect on the grade collection efficiency of the dual-layer granular bed than of the single-layer granular *** dual-layer granular bed provides a high collection efficiency and low pressure *** relationship between the grade collection efficiency and the Stokes number(St)based on the inlet gas velocity is *** St is below a threshold,the grade collection efficiency remains stable;if St is in value above threshold,the grade collection efficiency increases linearly with lg(St).As the bed depth of the lower layer of fine granules increases,the threshold for St shifts forward.

关键词： Dual-layer granular bed filter Pressure drop Grade collection efficiency Stokes number

Experimental Study on Flow Boiling Heat Transfer Characteristics of Microencapsulated Phase Change Material Suspension

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Journal of Thermal Science 2023年第4期32卷 1547-1557页

作者： TAN Zhenyu li xunfeng HUAI Xiulan CHENG Keyong CHEN Junlin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Nanjing Institute of Future Energy System Nanjing211135China

Due to its core phase change characteristics,microencapsulated phase change material(MPCM)can make many base fluids have better heat transfer *** this paper,the flow boiling heat transfer characteristics of fluorinated liquid-based microencapsulated phase change material suspension(MPCMS)through vertical transparent quartz channel were *** effects of MPCM core phase change temperature and suspension flow velocity on boiling heat transfer coefficient and critical heat flux were discussed,*** results show that the appropriate concentration of MPCMS can enhance both the boiling heat transfer coefficient and the critical heat *** strengthening effect becomes weak with the increase of suspension flow *** maximum strengthening rates of critical heat flux appear at 0.05 m/s,which are 25%(MPCMS(70℃)),16%(MPCMS(58℃))and 10%(MPCMS(28℃)).The phase change temperature of the MPCM core has important effects on the boiling heat transfer coefficient and the critical heat *** results showed that the MPCM with core phase change temperature higher than the boiling temperature of base fluid has the best enhancement *** bubble behavior in vertical tube with different heat flux can be observed by high-speed photography *** particle core phase change in MPCMS inhibits the aggregation of bubbles and forms many small bubbles to enhance heat *** work lays a foundation for further exploring the industrial application of MPCMS.

关键词： flow boiling enhancement flow visualization suspension microencapsulated phase change material

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

Effect of cavitating flow on forced convective heat transfer: a modeling study

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Chinese Science Bulletin 2014年第14期59卷 1580-1590页

作者： Jun Cai xunfeng li Bin liu Xiulan Huai Institute of Engineering Thermophysics Chinese Academy of Sciences

With water as working medium,a numerical study on liquid convection heat transfer accompanied by cavitating flow in a circular tube was conducted by combining mixture model and Schnerr–Sauer cavitation mode in the commercial code,Ansys *** is instigated by setting a restriction orifice in the circular *** simulation results show that cavitation occurs around the wall of the restriction orifice and disappears at the downstream *** comparison of local heat transfer coefficients under the same mass flow rate indicates that,heat transfer is significantly augmented at the downstream regions of the restriction orifice because of the occurrence of *** analysis on the characteristics of cavitating and noncavitating flows confirms that the occurrence of cavitation can increase the turbulence intensity under the same mass flow rate,which is the origin for heat transfer to be *** on it,the effects of such factors as inlet pressure and ratio of orifice to pipe diameter on cavitation enhanced heat transfer were further investigated for the purpose of application.

关键词：强迫对流换热空化流建模 FLUENT 节流孔板局部传热系数质量流率 ANSYS

STRUCTURE DESIGN OF THE BEIJING SPECTROMETERⅢBEAM PIPE

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Chinese Journal of Mechanical Engineering 2008年第3期21卷 1-6页

作者： ZHENG lifang JI Quan WANG li li xunfeng XU Shaowang DONG Sujun ZHAO libin liU Jianping School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Department of Flight Vehicle Design and Applied Mechanics Beihang University Beijing 100083 China School of Mechanical Engineering Tianjin University Tianjin 300072 China

The Beijing spectrometer Ⅲ （BESⅢ） beam pipe is in the center of the BESⅢ, which is the detector of the upgrade project of Beijing electron and positron collider （BEPC Ⅱ）. Electrons and positrons collide in the BESⅢ beam pipe. According to the demands of the BEPC Ⅱ, a key program of Chinese Academy of Sciences, the BESⅢ beam pipe is designed based on the finite elements analysis. The BESIII beam pipe is installed in the inner cylinder of the BESⅢ drift chamber. As a vacuum tube, the BESIII beam pipe is designed as 1 000 mm in length, 63 mm in inner diameter and 114 mm in outer diameter, respectively. The BESIII beam pipe consists of a central beryllium pipe cooled by EDM-1, the oil No.1 for electric discharge machining, and two extended copper pipes cooled by deionized water （DW）. The three parts are jointed by vacuum welding. Factors taken into account in the design are as follows. ① The wall thickness of the central beryllium pipe should be designed as small as possible to reduce the multi-scattering and improve the particle momentum resolution. And the wall thickness of the extended copper pipe should be designed as large as possible to protect the detectors from the backgrounds. ②The BESⅢ beam pipe must be sufficiently cooled to avoid the damage and prevents its influence to the BESⅢ drift chamber （DC） operation. The inner surface temperature of the DC inner cylinder must be maintained at 293±2 K. ③ The magnetic permeability of the materials used in the BESⅢ beam pipe must be less than 1.05 H/m to avoid large magnetic field distortions. ④ The static pressure of the vacuum chamber of the BESⅢ beam pipe must be less than 800 μPa. The simulating results show that the designed structure of the BESⅢ beam pipe satisfies the requirements mentioned above. The structure design scheme is evaluated and adonted hv the headouarters of BEPCⅡ.

关键词： Beam pipe Beijing spectrometer Ⅲ Structure design Beijing electron and positron collider Ⅱ BESⅢ

Acetone hydrogenation in exothermic reactor of an isopropanol–acetone–hydrogen chemical heat pump: effect of intra-particle mass and heat transfer

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Chinese Science Bulletin 2014年第28期59卷 4436-4443页

作者： Yanjun Duan Min Xu Xiulan Huai xunfeng li Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

Intra-particle mass and heat transfer plays an important role in performance of the exothermic fixed-bed reactor for an isopropanol–acetone–hydrogen chemical heat pump. In this work, an exothermic fixed-bed reactor model, taking into account the actual packing structure, is established in the commercial software Fluent. A 120°segment of a tube with tube-to-particle diameter ratio(n) of4, where realistic particles are packed and set to porous media, is used to simulate the 3D external flow, concentration and temperature fields in the exothermic packed-bed reactor. The influence of catalyst particle diameter(dp) and micropore diameter(d0) on the intra-particle temperature,species distribution, reaction rate and selectivity is discussed. The appropriate dpand d0 are obtained. Simulation results showed that intra-particle temperature gradient is not obvious. Large dpand small d0 lead to remarkable gradient of reaction rate inside the catalyst particle and the decrease in the catalyst efficiency and reduce the acetone conversion and the selectivity in isopropanol. The optimal results reveal that the spherical catalyst with dpof 1 mm and dporeof 10 nm is appropriate for high-temperature acetone hydrogenation.

关键词：颗粒直径化学热泵异丙醇丙酮加氢热反应器传热传质

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带层次结构效用可转移合作对策的Shapley值及其简化计算方法

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系统科学与数学 2016年第11期36卷 1913-1920页

作者：胡勋锋李登峰福州大学经济与管理学院福州350108

从分配式角度引入了带层次结构效用可转移合作对策的Shapley值,因此该值的商对策性质就成了一个很自然的推论.为了方便计算,文章还引入了该值的联盟式描述及简化联盟式描述.最后,给出了利用简化联盟式描述来计算该值的具体过程.

关键词：合作对策联盟结构层次结构 Shapley值

BES Ⅲ束流管温度场的数值模拟及实验研究

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原子能科学技术 2014年第4期48卷 734-739页

作者：郑莉芳王立纪全李勋锋刘建平北京科技大学机械工程学院北京100083 中国科学院高能物理研究所北京100049 中国科学院工程热物理所北京100190 北京科技大学机械工程学院北京100083

束流管安装在北京谱仪（BESⅢ）子探测器漂移室的内筒,新一代北京正负电子对撞机（BEPCⅡ）在运行时将会有更多的同步辐射和高次模辐射热负荷作用于束流管的内表面,过高的热量和过大的温度变化幅度将会影响漂移室的正常粒子的探测。本... 详细信息

束流管安装在北京谱仪（BESⅢ）子探测器漂移室的内筒,新一代北京正负电子对撞机（BEPCⅡ）在运行时将会有更多的同步辐射和高次模辐射热负荷作用于束流管的内表面,过高的热量和过大的温度变化幅度将会影响漂移室的正常粒子的探测。本文对束流管温度场进行了有限元数值模拟和实验研究,并对漂移室内筒的内壁面温度进行了数值分析。结果表明,当束流管内壁辐射热负荷在0~750 W变化时,设定束流管的中心管冷却油和外延管冷却水的进口温度分别为291.4K和291.6K,可将漂移室内筒的内壁温度控制在292.8~293.9K,满足（293±2）K的要求,保证了BESⅢ的精确粒子探测和BEPCⅡ的正常运行。

关键词： BESⅢ 束流管温度数值模拟实验

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红外测温探头防护性能数值模拟研究

工程热物理学报 2024年第1期45卷 205-211页

作者：叶志鹏李勋锋刘艳谭震宇淮秀兰中国科学院工程热物理研究所北京100190 中国科学院大学工程科学学院北京100049 中科南京未来能源系统研究院南京211135

本文针对高温叶栅试验台的红外测温需求,设计了测温探头的防护结构,在尽量不干扰主流的前提下实现对测温探头的热防护与污染防护。通过CFD计算,分析了该结构设计的合理性。对冷却空气入口总压的影响进行分析,发现入口总压过小,会造成探... 详细信息

本文针对高温叶栅试验台的红外测温需求,设计了测温探头的防护结构,在尽量不干扰主流的前提下实现对测温探头的热防护与污染防护。通过CFD计算,分析了该结构设计的合理性。对冷却空气入口总压的影响进行分析,发现入口总压过小,会造成探头的高温烧蚀,总压过大,则会对主流产生较大干扰。最后对冷却水入口流速进行分析,结果表明,探头的冷却效果随流速增大而增强,当流速大于2 m/s时,冷却效果基本不随流速变化而变化。

关键词：红外测温探头防护性能空气吹扫水冷保护