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Effect of operational and geometric parameters on the hydrodynamics of a Wurster coater:A CFD-DEM study

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Particuology 2024年第2期85卷 62-76页

作者： Yinqiang Song tuo zhou Ruiqi Bai Man Zhang Hairui Yang Department of Energy and Power Engineering Tsinghua UniversityBeijing100084China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua UniversityBeijing100084China State Key Laboratory of Power System and Generation Equipment Tsinghua UniversityBeijing100084China

A coupled CFD-DEM method was used to study the hydrodynamics of a Wurster ***,the CFD part of the model was validated by the accurate prediction of the pressure drops over a pseudo-2D fluidized bed under various gas *** effect of gas velocity,gap height,tube length and batch volume of the particles on the cycle time and the residence time of the particles was thoroughly *** central jet gas velocity ui was found to speed up the particle cycle but undermine the coating *** gas velocity at the horizontal transport zone u2 was able to promote the horizontal transport of the particles but should not be too high,otherwise,it would obstruct the normal falling back of the particles in the downward *** gap heights would decrease the coating efficiency but tube length had little impact on *** increment of batch volume would commonly abase the cycle time and the working efficiency under a given *** de-fluidization problem arose when the batch volume increased to 550 ***,this problem could be swept out by the optimization of u1 and *** a mixture of different sizes,the coarse particles enjoyed higher coating efficiency and could travel closer to the *** may shield the fine particles from getting enough coating liquids,and thus coarse particles and fine particles were not recommended to get coated in the same batch.

关键词： Numerical simulation CFD-DEM Wurster coater Hydrodynamics Cycle time Residence time

Effects of the inlet particle spatial distribution on the performance of a gas-solid cyclone separator

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Particuology 2024年第2期85卷 133-145页

作者： Yuge Yao Manxia Shang Xiwei Ke Zhong Huang tuo zhou Junfu Lyu Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China

The present study was aimed at the inlet particle spatial distribution of a gas-solid separator with high solid loading and investigated its effects on cyclone performance and the inner flow *** flow fields of a cyclone with different rectangular particle flow areas on the inlet surface were numerically simulated using a four-way coupling *** simulated results indicate that reducing the inlet particle flow area and lowing the inlet particle position can effectively reduce the scattered particles inside the cyclone separator and enhance the separation *** gathering the particles to the centerline can also weaken the particle *** particles near the roof account for the swirling particle ceiling *** inlet particle spatial distribution affects the pressure drop mainly by affecting the gas tangential velocity in the cylinder ***,compared to the hori-zontal particle distribution on the inlet surface,the vertical particle distribution has greater effects on cyclone performance.

关键词： Gas-solid cyclone Inlet particle spatial distribution Four-way coupling Separation efficiency Scattered particle

Coupled Heat Transfer Simulation of the Spiral Water Wall in a Double Reheat Ultra-supercritical Boiler

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Journal of Thermal Science 2018年第6期27卷 592-601页

作者： DONG Jiancong zhou tuo WU Xiaojiang ZHANG Jian FAN Haojie ZHANG Zhongxiao School of Mechanical Engineering Shanghai Jiao Tong University Institute of Engineering Thermophysics Chinese Academy of Sciences Department of Research and Development Shanghai Boiler Works Co. Ltd.

This paper presented a coupled heat transfer model combining the combustion in the furnace and the ultra-supercritical(USC) heat transfer in the water wall tubes. The thermal analysis of the spiral water wall in a 1000 MW double reheat USC boiler was conducted by the coupled heat transfer simulations. The simulation results show that there are two peak heat flux regions on each wall of spiral water wall, where the primary combustion zone and burnt-out zone locate respectively. In the full load condition, the maximal heat flux of the primary combustion zone is close to 500 kW/m^2, which is higher than that in the conventional single reheat USC boilers. The heat flux along the furnace width presents a parabolic shape that the values in the furnace center are much higher than that in the corner regions. The distribution of water wall temperature has a perfect accordance with the heat flux distribution of the parabolic shape curves, which can illustrate the distribution of water wall temperature is mainly determined by heat flux on the water wall. The maximal water wall temperature occurs at the middle width of furnace wall and approaches 530°C, which can be allowed by the metal material of water wall tube 12Cr1MoVG. In the primary combustion zone, the wall temperatures in half load are almost close to the values in 75% load condition, caused by the heat transfer deterioration of the subcritical pressure fluid under the high heat flux condition. The simulation results in this study are beneficial to the better design and operational optimization for the double reheat USC boilers.

关键词： coupled model heat transfer spiral water wall double reheat ultra-supercritical

A state-of-the-art review on transition between the fast fluidization and pneumatic transport of Geldart group B particles

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Particuology 2023年第2期73卷 78-94页

作者： Boyu Deng Yi Zhang Man Zhang Yi Ding tuo zhou Xinhua Yang Zhong Huang Hairui Yang Guangxi Yue State Key Laboratory of Power Systems Department of Energy and Power EngineeringTsinghua UniversityBeijing100084China China Electric Power Planning&Engineering Institute Beijing100120China SDIC Power Holding Co. LtdBeijing100034China

The fluidization state in the circulating fluidized bed(CFB)boiler is crucial to its stable and safe ***,up to now,the research field has not reached unanimity on whether the fluidization regime that the upper furnace of the boiler operates in is the fast fluidization or pneumatic *** this end,this paper reviewed relevant research on the transition between the fast fluidization and pneumatic transport of Geldart group B particles,including the flow characteristics of the fast fluidization,the transition condition between the fast fluidization and pneumatic transport,the determination methods of the transport velocity utr and saturation carrying capacity G_(s)* and the influencing factors on these two *** research findings can provide certain guidelines for the design and optimization of the CFB boiler,and result in plenty of prediction correlations for utr and G_(s)*.Nonetheless,owing to insufficient data available on Geldart group B particles,especially the ones obtained under high temperature or pressure conditions and in large-scale CFB apparatuses,the existing correlations are not well suited for the prediction of u_(tr) and G_(s)* of Geldart group B ***,further efforts are urgently demanded on the fast fluidization transition of Geldart group B particles.

关键词： Fast fluidization transition Transport velocity Saturation carrying capacity Geldart group B particles Circulating fluidized bed

Laser-rewritable room temperature phosphorescence based on in-situ polymerized tartaric acid

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Science China Chemistry 2024年第9期67卷 3029-3038页

作者： tuo-Yu zhou Tai-Wen Li Hai-Fu Zhang Rui-Lin Chai Qian Zhao Penglin Zhang Guang-Yue Li Qian-Wen Wang Chang Li Yu Shu Zhi Fan Sheng-Hua Li College of Chemical Engineering and Materials Science College of SciencesTianjin University of Science&TechnologyTianjin 300457China College of Chemical Engineering North China University of Science and TechnologyTangshan 063210China Tianjin Key Laboratory of Multiplexed Identification for Port Hazardous Chemicals Tianjin University of Science&TechnologyTianjin 300457China

Organic room temperature phosphorescence(RTP)materials have potential applications in information technology and ***,the precise control of the afterglow in reversible manners remains challenging for organic ***,we report a kind of organic RTP material fabricated by simple heating mixtures of tartaric acid(TA)and aromatic acids,which can switch their phosphorescence by *** mixtures show tunable phosphorescence from indigo to orange with phosphorescence efficiency of up to 53.99% due to locking different organic luminogens by the TA-formed matrix through the noncovalent *** afterglow of those materials lasts a few seconds and disappears by water fumigation,which can be repeated in response to wet/heat *** drop-casting those materials on glass slides,a laser-repatternable phosphorescence is achieved by facile laser direct writing and quenched by water *** results open the opportunity for the design of smart stimuli-responsive phosphorescence materials from sustainable natural products.

关键词： room temperature phosphorescence tunable afterglows tartaric acid laser direct writing stimuli-response

Fabrication of patterned graphitized carbon wires using low voltage near-field electrospinning, pyrolysis, electrodeposition, and chemical vapor deposition

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Microsystems & Nanoengineering 2020年第1期6卷 1341-1352页

作者： Derosh George Adrian Garcia Quang Pham Mario Ramos Perez Jufeng Deng Michelle Trang Nguyen tuo zhou Sergio OMartinez-Chapa Yoonjin Won Chong Liu Roger CLo Regina Ragan Marc Madou Mechanical and Aerospace Engineering University of CaliforniaIrvineUSA Chemical Engineering and Materials Science University of CaliforniaIrvineUSA Materials and Manufacturing Technology University of CaliforniaIrvineUSA School of Engineering and Sciences Tecnologico de MonterreyMonterreyMexico Mechanical Engineering Dalian University of TechnologyDalianChina Chemical Engineering California State UniversityLong BeachUSA Present address:Mechanical Engineering Centro de Ensenanza Tecnica y Superior UniversidadMexicaliMexico

We herein report a high-resolution nanopatterning method using low voltage electromechanical spinning with a rotating collector to obtain aligned graphitized micro and nanowires for carbon nanomanufacturing.A small wire diameter and a small inter-wire spacing were obtained by controlling the electric field,the spinneret-to-collector distance,the pyrolysis parameters,the linear speed of the spinneret,the rotational speed of the *** a simple scaling analysis,we show how the straightness and the diameter of the wires can be controlled by the electric field and the distance of the spinneret to the collector.A small inter-wire spacing,as predicted by a simple model,was achieved by simultaneously controlling the linear speed of the spinneret and the rotational speed of the *** drying of the polymer nanowires enabled the facile fabrication of suspended wires over various *** polyacrylonitrile wires were carbonized using standard stabilization and pyrolysis to obtain carbon *** carbon nanowires with a diameter of<50 nm were *** also established a method for making patterned,highly graphitized structures by using the aforementioned carbon wire structures as a template for chemical vapor deposition of *** patterning technique offers high throughput for nano writing,which outperforms other existing nanopatterning techniques,making it a potential candidate for large-scale carbon nanomanufacturing.

关键词： nanowires carbon field

桥丝式电雷管无损检测系统电热转换灵敏度的研究

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计量学报 2005年第3期26卷 225-227页

作者：廖晓纬周拓宇淮南师范学院安徽淮南232001 上海交通大学上海200030

针对桥丝式电雷管电热响应无损检测的通用测试系统,提出了系统的电热转换灵敏度的概念并推出其一般表达式。利用测试系统的这个特性参数,能方便地将输出端的电压数字量换算成被测对象的温升,大大地简化计算,可以作为研究电热响应无损检... 详细信息

针对桥丝式电雷管电热响应无损检测的通用测试系统,提出了系统的电热转换灵敏度的概念并推出其一般表达式。利用测试系统的这个特性参数,能方便地将输出端的电压数字量换算成被测对象的温升,大大地简化计算,可以作为研究电热响应无损检测方法的一个重要手段。

关键词：计量学电热响应转换灵敏度无损检测系统电雷管

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气体再燃低NO_x燃烧器的喷口射流特性

燃烧科学与技术 2008年第3期14卷 281-287页

作者：朱明张忠孝周托上海理工大学动力工程学院上海200093

以宝钢350 MW锅炉为原型建立了冷态模拟实验台,用热球风速仪对气体再燃低NOx燃烧器喷口的流动特性进行了实验研究,并利用射流混合理论解释了再燃气体和炉内旋转气流的混合程度对NOx还原的影响.分析了再燃速度的改变对燃烧器出口区域和... 详细信息

以宝钢350 MW锅炉为原型建立了冷态模拟实验台,用热球风速仪对气体再燃低NOx燃烧器喷口的流动特性进行了实验研究,并利用射流混合理论解释了再燃气体和炉内旋转气流的混合程度对NOx还原的影响.分析了再燃速度的改变对燃烧器出口区域和实验炉内的空气动力场的流场的影响,并提出了有效混合度的概念.实验结果表明,保持一次风速度为21 m/s不变,再燃气体速度为32 m/s时,再燃气体偏离射流轴线较早,不能射入炉膛旋转气流的中心部位;当再燃气体速度为48 m/s时,导致再燃气体射穿炉内旋转气流;再燃风速度为40 m/s时,射流中心夹角小,有效混合度大,混合强烈,对NOx的还原充分,可认为是最佳工况.

关键词：气体再燃低NOx燃烧器空气动力场射流混合度

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利用井中偶极声源远场辐射特性的远探测测井

地球物理学报 2012年第8期55卷 2798-2807页

作者：唐晓明魏周拓中国石油大学(华东)地球科学与技术学院声学测井联合实验室青岛266555

远探测声波测井技术近年来的一个重要进展是利用偶极声波探测仪器来发射和接收地层深部的反射信号.本文论述了这种偶极声波远探测技术的基本原理和方法,并结合数值模拟计算验证了该方法的可行性及灵敏度.具体来说,井中偶极声源向地层深... 详细信息

远探测声波测井技术近年来的一个重要进展是利用偶极声波探测仪器来发射和接收地层深部的反射信号.本文论述了这种偶极声波远探测技术的基本原理和方法,并结合数值模拟计算验证了该方法的可行性及灵敏度.具体来说,井中偶极声源向地层深部辐射出纵波、SH和SV型横波,其中SH型横波具有很宽的辐射覆盖及较高的反射灵敏度,是偶极横波远探测的重要依据.在慢速地层中,偶极辐射的纵波具有振幅强、灵敏度高的特征,也可以用于远探测测井.偶极远探测的另一个重要特征是其对反射体的方位灵敏度,这是由于声源为指向性发声的结果.采用四分量的数据采集方式便可以确定反射体走向的方位.在理论分析的基础上,我们用实际例子说明偶极声波远探测的重要特征及其有效性.

关键词：井孔声波偶极声源辐射反射声波成像