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collection efficiency of a monitor parallel plate ionization chamber for pencil beam scanning proton therapy

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Nuclear Science and Techniques 2020年第2期31卷 1-10页

作者： Rong-Cheng Han Yong-Jiang Li Yue-Hu Pu Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China Shanghai APACTRON Particle Equipment Co.Ltd Shanghai 201800China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210China

The collection efficiency of monitor parallel plate ionization chambers is the main uncertainty in the beam control of pencil beam scanning *** calculation methods for collection efficiency in photon or passive scattering proton systems have not considered the characteristics of non-uniform charge density in pencil beam scanning *** this study,Boag’s theory was applied to a proton pencil beam scanning *** transverse distribution of charge density in the ionization chamber was considered to be a Gaussian function and an analytical solution was derived to calculate collection efficiency in the beam spot *** calculation method is called the integral method and it was used to investigate the effects of beam parameters on collection *** was determined that collection efficiency is positively correlated with applied voltage,beam size,and beam energy,but negatively correlated with beam current ***,it was confirmed that collection efficiency is improved when the air filling the monitor parallel plate ionization chamber is replaced with nitrogen.

关键词： collection efficiency Monitor ionization chamber Pencil beam scanning Proton therapy

collection efficiency of Cylindrical and Elliptic Cyclone Dust Collectors with Vortex Breaker

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Journal of Thermal Science 2000年第3期9卷 257-264页

作者： AkiraOgawa Tatuyaugai DepartmentofMechanicalEng. CollegeofEng.NihonUniv.T－963Tamura－machiKooriyamashiJapan JatcoTransTechnologyLtd. T－417－2571Imaizumi700－1Fuji－shiShizuokaPrefecturejapan

The cyclone dust collector is applied to many kinds of industries and also there are many types of cyclones which are selected for the application and the placement of the establishment. However the cross section of these cyclones is the circular cylindrical section for the optimum condition of the turbulent rotational flow. However from the energy consumption and the collection efficiency points of view, the circular cross section of the cyclone is not always recommended but the elliptic cross section is recommended. Therefore in this paper, the detailed experimental results of the collection efficiency for the circular cross section and for the elliptic cross sections of the eccentricity =0.5,0.6and 0.7 are reported. The test dust for these experiments is fly-ash of the mean diameter Xpm=18.0 μm and 18.3 μm. The feed particle concentration is Co=1.0-50 g/m3.

关键词： elliptic cyclone eccentricity collection efficiency fly-ash feed particle concentration pressure drop.

Contributions of the Secondary Jet to the Tangential Velocity Distribution and to the collection efficiency of the Fixed Guide Vane Type Axial Flow Cyclone Dust Collector

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Journal of Thermal Science 2015年第6期24卷 503-509页

作者： Akira Ogawa Hideki Anzou So Yamamoto Mituru Shimagaki Tokyo Japan

In order to control the maximum tangential velocity V?m(m/s)of the turbulent rotational air flow and the collection efficiencyηc(%)using the fly ash of the mean diameter X R50=5.57?m,two secondary jet nozzles were installed to the body of the axial flow cyclone dust collector with the body diameter D1=*** in order to estimate V?m(m/s),the conservation theory of the angular momentum flux with Ogawa combined vortex model was *** comparisons of the estimated results of V?m(m/s)with the measured results by the cylindrical Pitot-tube were shown in good *** also the estimated collection efficienciesηcth(%)basing upon the cut-size Xc(?m)which was calculated by using the estimated V?m(m/s)and also the particle size distribution R(Xp)were shown a little higher values than the experimental results due to the re-entrainment of the collected *** best method for adjustment ofηc(%)related to the contribution of the secondary jet flow is principally to apply the centrifugal effect?c(1).Above stated results are described in detail.

关键词： Axial Flow Cyclone Dust Collector Maximum Tangential Velocity Cut-Size Particle Size Distribution collection efficiency Reynolds number Centrifugal Effect

Simulation and experimental verification of the dependence of collection efficiency on the shape of a dual micropipette

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Science China Chemistry 2011年第8期54卷 1311-1318页

作者： GAO Zhao LI Bo ZHAO WenBo CHEN Yong HU Mo LIANG ZhongWei ZHOU ShuLin SHAO YuanHua College of Chemistry and Molecular Engineering Peking University Beijing 100871 China School of Mathematical Sciences Peking University Beijing 100871 China Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China

The current responses of a generation/collection (G/C) system based on dual micropipettes are simulated by the boundary element (BE) method, from which the collection efficiencies for various pipettes with different geometries are calculated. The influence of the shape of a dual micropipette on the collection efficiency, such as curvature and symmetry of the pipette, as well as the thickness of glassy band between generator and collector, is presented and discussed in detail. Moreover, the simulation results have been tested using the experiments of potassium and sodium ions transfers facilitated by dibenzo-18-crown-6 (DB18C6) at the water/1,2-dichloroethane (W/DCE) interface. These results demonstrate that the BE method is an efficient and useful approach for the simulation of collection efficiency of symmetric geometries of dual micropipettes operating in the G/C mode under transport conditions of diffusion control. However, there are still some problems for the cases of asymmetric dual micropipettes, which show rather large differences between the values of simulated and experimental ones. This work also indicates that such an ionic G/C technique should have advantages in applications when the dual pipettes have symmetric geometries.

关键词： boundary element method dual micropipettes collection efficiency simulation

Estimation of collection efficiency Depended on FeedParticle Concentration for Axial Flow Cyclone DustCollector

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Journal of Thermal Science 1999年第3期8卷 143-157页

作者： Akira Ogawa(Department of Mechanical Engineering, College of Engineering, Nihon University T-963-8642.Tokusada, Tamura-machi, Kooriyama-shi, Japan. Fax.0249-56-8860) Department of Mechanical Engineering College of Engineering Nihon University T-963-8642 Japan

A cyclone dust collector is applied in many industries. Especially the axial flow cyclone is the mostsimple construction and it keeps high reliability for maintenance. On the other hand, the collectionefficiency of the cyclone depends not only on the inlet gas velocity but also on the feed particle concentration. The collection efficiency increases with increasing feed particle concentration. However untilnow the problem of how to estimate the collection efficiency depended on the feed particle concentrationis remained except the investigation by Muschelknautz & Brunner~[6]. Therefore in this paper one ofthe estimate method for the collection efficiency of the axial flow cyclones is proposed. The applicationto the geometrically similar type of cyclone of the body diameters D_1=30, 50, 69 and 99 mm showedin good agreement with the experimental results of the collection efficiencies which were described indetail in the paper by Ogawa & Sugiyama~[8].

关键词： axial flow cyclone dust collector collection efficiency cut-size Reynoldsnumber centrifugal effect re-entrainment in dust bunker critical feed particle concentration fly-ash high concentration low concentration.

Effects of Different Rainwater Diversion Patterns on Rainwater collection efficiency and Water Utilization efficiency in Cornfield

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Meteorological and Environmental Research 2015年第8期6卷 54-56页

作者： Wang Jianxin Wang Panlei Duan Zongyan Pan Yanhua Chen Shihua Lu Yao Institute of Agricultural Resources & Environment Yunnan Academy of Agricultural Sciences

Four rainwater diversion patterns including undisturbed soil ditch （T1）, slope compaction （T2）, asbestos sheet covering after compac- tion （T3） and plastic film covering after compaction （T4） were set in cornfield in arid areas of Yunnan Province, and effects of various patterns on rainwater collection efficiency, water utilization efficiency and corn yield were studied. The results shows that rainwater collection efficiency, water utilization efficiency and corn yield of the four diversion patterns presented the same trend, namely T4 〉T3 〉T2 〉T1. Overall, rainwater collection efficiencies of the four diversion patterns ranged from 41.7% to 58.7% ; compared with T1, water utilization efficiencies of T2 ,T3 and T4 increased by 34.9%, 53.5% and 92.5%, and maize yields of them improved by 1 767.0, 1 981.5 and 2 385.0 kg/hm2.

关键词： Arid areas of Yunnan Maize Diversion pattern collection efficiency Water utilization efficiency China

Influence of wire spacing and plate spacing on electrostatic precipitation of nanoparticles: An approach involving electrostatic shielding and diffusion charging

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Particuology 2023年第9期80卷 127-139页

作者： Felipe de Aquino Lima Vádila Giovana Guerra Department of Chemical Engineering Federal University of São CarlosRodovia Washington LuísKm 235C.P.676CEP 13560-970São CarlosSPBrazil

Electrostatic precipitation is a process widely used as gas cleaning device,to removal particles from gas ***,in a conventional and well-sized precipitator,the collection efficiency decreases for ultrafine particles,making it difficult to employ this equipment for controlling nanoparticle *** paper investigates the influence of plate spacing(4 and 6.5 cm)and wire spacing(4,6,and 12 cm)on the electric current and nanoparticle collection efficiency,considering the effect of diffusion charging and electrostatic *** laboratory-scale dry wire-plate electrostatic precipitators with different plate spacings were tested for the collection of nanoparticles(6.15–241.4 nm)at three air velocities(1.9,2.9,and 3.9 cm/s).The results demonstrated the effectiveness of the equipment in removing nanoparticles(99.9%)under the highest electric *** values of the wire spacing led to increases in the current and the collection *** was associated with reduced electrostatic shielding,which is more evident in smaller ducts with a higher density of field *** is expected that the findings should improve knowledge on electrostatic precipitation of nanoparticles,enabling optimization of collection efficiency by considering the effects of geometric parameters.

关键词： Electrostatic precipitation Nanoparticles collection efficiency Plate spacing Wire spacing

Separating polydisperse particles using electrostatic precipitators with wire and spiked-wire discharge electrode design

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Particuology 2018年第3期16卷 10-17页

作者： Soren Sander Steffen Gawor Udo Fritsching Process Engineering Stiftung Institut ffir Werlcstofftechnik Badgasteiner Strasse 3 28359 Bremen Germany Particles and Process Engineering University of Bremen Bibliothekstrasse 1 28359 Bremen. Germany

Numerical simulations of electrostatic precipitators featuring wire and spiked electrode designs were performed to determine particle behavior and separation efficiency. The applied-voltage mechanism that alters the flow structure of particles through ionic winds and mean electric fields are revealed. Numeri- cal studies throughout the past years have shown these structures for channel and pipe configurations. However, less attention was given to field averaging for the ni,~r-product and electric field. Our study focuses on this averaging and illustrates relevant differences between multidimensional setups concern- ~ng these fields. Turbulence was modeled using the Reynolds-averaged Navier-Stokes equations with a second-order Reynolds-stress-model closure. A high three-dimensionality of the ionic wind-induced turbulence is presented. This leads to an increase in the submicron-particle precipitation rate. The results confirm the dependence of separation efficiency on particle density and permittivity, thereby showing the advantages of spiked wires compared with wire-plate setups used in electrostatic precipitators.

关键词： Electro-hydrodynamic CFD simulation Electrostatic particle precipitation Electrode design collection efficiency

Experimental and numerical study of a gas cyclone with a central filter

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Particuology 2022年第4期20卷 47-59页

作者： Zihui Zhang Sijie Dong Kejun Dong Li'an Hou Wenzheng Wang Yi Wei Bo Wang Key Laboratory of Western China's Environmental Systems(Ministry of Education)and Engineering Research Center of Fine Particles Pollution Control Technology and Equipment of Gansu Province College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Centre for Infrastructure Engineering School of EngineeringWestern Sydney UniversityPenrithNSW 2751Australia Xi'an High-Tech Institute Xi'an 710025China Gansu Chemical Industry Research Institute Co. Ltd.Lanzhou 730000China

This paper studies a novel gas cyclone with a cylindrical fiter face installed in the center from the vortex finder to the bottom *** experimental results show that this composite cyclone has a higher collection fficiency and a lower pressure drop than the original *** mechanisms for the improvement are analyzed by both physical experiments and numerical *** measuring dust samples collected at different places it is revealed that the center filter can prevent fine particles from entering the inner vortex and escaping,which accounts for the increase of the collection *** addition,the flow field of the composite cyclone is simulated by computational fluid dynamics and compared with that of the original *** analysis shows that with the filter layer installed,the swirling flow disappears in the vortex finder,which decreases the kinetic energy dissipation and hence lowers the pressure drop.

关键词： Cyclone Filtration Porous media model collection efficiency Pressure drop