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Numerical investigation of laminar heat transfer and nanofluid flow between two porous horizontal concentric cylinders 被引量:8
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作者 Mehdi MIRZAEYAN Davood TOGHRAIE 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第7期1976-1999,共24页
In this study, the laminar heat transfer and nanofluid flow between two porous horizontal concentric cylinders was investigated. The problem is investigated in two different geometries and the Re=10, 25, 50, 75, 100 a... In this study, the laminar heat transfer and nanofluid flow between two porous horizontal concentric cylinders was investigated. The problem is investigated in two different geometries and the Re=10, 25, 50, 75, 100 and volume fraction 0, 0.2%, 0.5%, 2% and 5% that related to copper nanoparticles, and porous medium porosity of 0.5 and 0.9. Compared to the first geometry, the convective coefficient in the second geometry increases by 8.3%, 7% and 5.5% at Reynolds numbers of 100, 75 and 50, respectively. Comparison of the outlet temperatures for two heat fluxes of 300 and 1200 W/m^2 indicates a 2.5% temperature growth by a fourfold increase in the heat fluxes. Also, the higher Nusselt number is associated with the second geometry occurring at porosities of 0.9 and 0.5, respectively. In both geometries, the Nusselt number values at the porosity of 0.9 are higher, which is due to the increased nanofluid convection at higher porosities. The velocity of the nanofluid experiences a two-fold increase at the outlet compared to its inlet velocity in the first geometry and for both porosities. Similarly, a three-fold increase was achieved in the second geometry and for both porosities. 展开更多
关键词 porous horizontal concentric cylinders nanofluid flow PERMEABILITY heat transfer
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Geometric shapes of the interface surface of bicomponent flows between two concentric rotating cylinders
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作者 李开泰 史峰 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2008年第10期1363-1376,共14页
In this paper, the shape problem of interface of bicomponent flows between two concentric rotating cylinders is investigated. With tensor analysis, the problem is reduced to an energy functional isoperimetric problem ... In this paper, the shape problem of interface of bicomponent flows between two concentric rotating cylinders is investigated. With tensor analysis, the problem is reduced to an energy functional isoperimetric problem when neglecting the effects of the dissipative energy caused by viscosity. We derive the associated Euler-Lagrangian equation, which is a nonlinear elliptic boundary value problem of the second order. Moreover, by considering the effects of the dissipative energy, we propose another total energy functional to characterize the geometric shape of the interface, and obtain the corresponding Euler-Lagrangian equation, which is also a nonlinear elliptic boundary value problem of the second order. Thus, the problem of the geometric shape is converted into a nonlinear boundary value problem of the second order in both cases. 展开更多
关键词 bicomponent flow interface surface Navier-Stokes equations concentric rotating cylinders
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Comparison of Rheometric Devices for Measuring the Rheological Parameters of Debris Flow Slurry 被引量:1
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作者 YANG Hong-juan WEI Fang-qiang +2 位作者 HU Kai-heng ZHOU Gong-dan LYU Juan 《Journal of Mountain Science》 SCIE CSCD 2015年第5期1125-1134,共10页
Soil samples with clay content ranging from 15% to 31%, were taken from three debris flow gullies in Southwest China. Three debris flow slurry samples were prepared and tested with four measuring systems of an Anton P... Soil samples with clay content ranging from 15% to 31%, were taken from three debris flow gullies in Southwest China. Three debris flow slurry samples were prepared and tested with four measuring systems of an Anton Paar Physica MCR301 rheometer, including the concentric cylinder system,the parallel-plate system, the vane geometry, and the ball measuring system. All systems were smoothwalled. Flow curves were plotted and yield stress was determined using the Herschel-Bulkley model,showing differences among the different systems.Flow curves from the concentric cylinder and parallelplate systems involved two distinct regions, the low shear and the high shear regions. Yield stresses determined by data fitting in the low shear region were significantly lower than the values from the inclined channel test which is a practical method for determining yield stress. Flow curves in the high shear region are close to those from the vane geometry and the ball measuring system. The fitted values of yield stress are comparable to the values from the inclined channel test. The differences are caused by wall-slip effects in the low shear region.Vane geometry can capture the stress overshoot phenomenon caused by the destruction of slurry structure, whereas end effects should be considered in the determination of yield stress. The ball measuring system can give reasonable results, and it is applicable for rheological testing of debris flow slurries. 展开更多
关键词 Debris flow SLURRY RHEOMETER concentric cylinder system Parallel plate system VANE Ball measuring system
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Performance of Dielectric Barrier Discharge Reactors on Elemental Mercury Oxidation in the Coal-Fired Flue Gas
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作者 安久涛 商克峰 +4 位作者 鲁娜 洪义 姜雨泽 李杰 吴彦 《Plasma Science and Technology》 SCIE EI CAS CSCD 2014年第2期155-160,共6页
The oxidation of elemental mercury (Hg~) by dielectric barrier discharge reactors was studied at room temperature, where concentric cylinder discharge reactor (CCDR) and surface discharge plasma reactor (SDPR) w... The oxidation of elemental mercury (Hg~) by dielectric barrier discharge reactors was studied at room temperature, where concentric cylinder discharge reactor (CCDR) and surface discharge plasma reactor (SDPR) were employed. The parameters (e.g. Hg^0 oxidation efficiency, energy constant, energy yield, energy consumption, and O3 concentration) were discussed. From comparison of the two reactors, higher Hg^0 oxidation efficiency and energy constant in the SDPR system were obtained by using lower specific energy density. At the same applied voltage, energy yield in the SDPR system was larger than that in the CCDR system, and energy consumption in the SDPR system was much less. Additionally, more 03 was generated in the SDPR system. The experimental results showed that 98% of Hg^0 oxidation efficiency, 0.6 J·L^-1 of energy constant, 13.7 μg·J^-1 of energy yield, 15.1 eV·molecule^-1 of energy consumption, and 12.7 μg·J^-1 of O3 concentration were achieved in the SDPR system. The study reveals an alternative and economical technology for Hg^0 oxidation in the coal-fired flue gas. 展开更多
关键词 surface discharge plasma reactor concentric cylinder discharge reactor ele- mental mercury mercury oxidation
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