Effect of the prandtl number on the convection field and the heat transfer during natural convection

Berkovskii, B. M.; Полевиков, В. К.

doi:10.1007/bf00838619

Cited by 19 publications

(8 citation statements)

References 12 publications

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“…In the former case, conventional central difference schemes can be used, but these schemes show instability in the convective diffusion regime. Berkovskii and Polevikov [28] proposed a good second order monotonic conservative scheme defined on a five point (nine point if half integer indices are taken into account) pattern:…”

Section: Methods Of Calculation Of Mass Transfer In Coaxial Cellmentioning

confidence: 99%

Cross-flow mass transfer in a model hexagonal system of hollow fiber membranes

et al. 2015

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A method for calculating external mass transfer in a contactor with transverse confined flow of a viscous incompressible liquid (gas) past a hollow fiber membrane at low Reynolds numbers has been pro posed. The method is based on the concept of array of hollow fiber membranes as a hexagonal system of par allel fibers to which the Kuwabara cell model with a known flowfield is applicable. Asymmetric membranes with macroporous permeable outer supports have been considered. A solution of the problem on the external Stokes flow past a hollow fiber membrane in the cell, taking into account the hydrodynamic permeability of the support, has been found in terms of the model. To describe the flow inside and outside the support, joining of the general solutions to the Stokes and Brinkman equations has been used. The Saffman slip condition has been set on the surface of the low permeability membrane. The dependences of the stream function, velocity components, and drag force upon the fiber packing density and support permeability and thickness have been revealed. Efficiency η of solute sorption by the fiber has been calculated for the flowfield found, assuming zero component concentration at the membrane surface (full absorption approximation). The dependences of η on the diffusion Peclet number, support permeability and thickness, and fiber packing density have been calculated. Direct 3D simulation of convective mass transfer in the contactor at low Reynolds numbers has been performed, and the cell model has been shown to be applicable to the calculation of the contactor with a predominantly two dimensional transverse flow.

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Section: Methods Of Calculation Of Mass Transfer In Coaxial Cellmentioning

confidence: 99%

Cross-flow mass transfer in a model hexagonal system of hollow fiber membranes

et al. 2015

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“…In order to describe the flow and temperature fields in the gas phase we used the time-dependent twodimensional convection equations in the Boussinesq approximation [16][17][18][19][20][21] while in the solid phase we considered the two-dimensional heat conduction equation [22,23].…”

Section: Formulation Of the Problem And Methods Of Solutionmentioning

confidence: 99%

Two-dimensional problem of natural convection in a rectangular domain with local heating and heat-conducting boundaries of finite thickness

Кузнецов¹,

Sheremet²

2006

Fluid Dyn

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Time-dependent natural convective heat transfer in a closed rectangular domain with heatconducting boundaries of finite thickness is investigated numerically in the case of local heating on the inner side of the vertical wall. Convection-radiation heat transfer takes place on one of the outer boundaries of the solution domain. The inhomogeneous temperature distribution in the gas cavity is clearly manifested when the Grashof number Gr > 10 6 . Circulation flows can be distinguished in various zones of the solution domain on the basis of the numerical investigations carried out. These flows are due to the effect of the heat-release source, the propagation of perturbations induced by elements of the rigid wall, and the dynamics of conductive heat transfer in the solid material. The scales of the effect of the Grashof number on the hydrodynamic and thermal characteristics are indicated.

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“…The process of transfer of energy, momentum and mass in these circumstances is described by the system of non-stationary partial differential equations [12,13], similar to [5][6][7]. It is considered that the temperature and concentration on the left border of the solution domain (chimney of TPP) do not depend on time.…”

Section: Thermophysical Basis Of Energy Technologiesmentioning

confidence: 99%

The formation of acid rain in the atmosphere, adjacent to the TTP with the joint-condensing of sulfur dioxide and water vapor

Gvozdyakov

Губин

Matveeva

2014

EPJ Web of Conferences

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Abstract. Presents the results of mathematical simulation of the condensation process of sulphur dioxide and water vapor on the condensation nuclei surface under the action of natural factors. Numerical investigations were carried out for the summer at a moderate speed of the wind. The influence of the parameter of condensation on the speed of the process of sulfuric acid drops formation in the air space was analyzed. Time ranges, sufficient for the formation of the acid rain sedimentation in the atmosphere, adjacent to the areas of thermal power station work were established. It is shown that the speed of air masses movement effects on the process of acid anthropogenic admixtures dispersion in the atmosphere. Approbation of the obtained results was carried out by checking the difference scheme conservative and solution of test problems.A significant contribution to the formation of sulfuric acid in the boundary layer of the atmosphere is contributed by thermal power plants [1]. When burning the natural fuel of power plants in the environment there are different pollutants [2]. Under the influence of natural factors the combustion products of coals may condense on the water droplets presenting in the atmosphere and reach the Earth's surface [3]. Most of them refers to the number of toxic, and even at relatively low concentrations cause the adverse effects on nature and human life [1,2]. Table 1 shows the values of acceptable amounts of some contaminants contained in the flue gas in power station.In this paper we study the processes of condensation of sulphur trioxide SO 3 and water vapor H 2 O. Sulphur dioxide is formed in flues boilers of power plants by partial oxidation of SO 2 (up to 5% of the total SO 2 ) from the combustion of high-sulphur fuels, and belongs to a class of mild-hazard products [1,2].Earlier in [5][6][7] the process of acid rain formation in the airspace adjacent to the power plants, at different air temperatures and wind speeds was investigated. It was intended that the formation of sulfuric acid drops occurs only due to condensation of sulfuric anhydride on the condensation nuclei surface.In real practice the atmosphere always contains water vapors of natural origin [7]. In addition, a significant increase of the water vapor concentration in the air is possible in areas adjacent to the power plants by emissions of H 2 O due to the work of the heat engineering equipment of the station [1]. The analysis of processes of sulfuric acid drops formation in the air upon jointly proceeding processes of condensation of SO 3 and H 2 O vapors on the condensation nuclei surface is of interest. This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Effect of the prandtl number on the convection field and the heat transfer during natural convection

Cited by 19 publications

References 12 publications

Cross-flow mass transfer in a model hexagonal system of hollow fiber membranes

Cross-flow mass transfer in a model hexagonal system of hollow fiber membranes

Two-dimensional problem of natural convection in a rectangular domain with local heating and heat-conducting boundaries of finite thickness

The formation of acid rain in the atmosphere, adjacent to the TTP with the joint-condensing of sulfur dioxide and water vapor

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