Effect of the days scrolling on the natural convection in an open ended storage silo

Ameziani, Djamel Eddine; Bennacer, Rachid; Bouhadef, Khedidja; Aberqi, Ahmed

doi:10.1016/j.ijthermalsci.2009.04.005

Cited by 14 publications

(11 citation statements)

References 26 publications

(29 reference statements)

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“…The thermal boundary conditions between the segment and the rest of the regions are discontinuous. Such discontinuous thermal boundary conditions have been addressed in the literature (Ameziani et al 2009). With local methods, such as finite differences, if the grid spacing is small compared to the boundary layer thickness near the discontinuity in the boundary condition, there is no need to regularize the discontinuity.…”

Section: Numerical Technique and Code Validationmentioning

confidence: 99%

Double-Diffusive Convection from a Discrete Heat and Solute Source in a Vertical Porous Annulus

et al. 2011

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This article reports a numerical study of double-diffusive convection in a fluidsaturated vertical porous annulus subjected to discrete heat and mass fluxes from a portion of the inner wall. The outer wall is maintained at uniform temperature and concentration, while the top and bottom walls are adiabatic and impermeable to mass transfer. The physical model for the momentum equation is formulated using the Darcy law, and the resulting governing equations are solved using an implicit finite difference technique. The influence of physical and geometrical parameters on the streamlines, isotherms, isoconcentrations, average Nusselt and Sherwood numbers has been numerically investigated in detail. The location of heat and solute source has a profound influence on the flow pattern, heat and mass transfer rates in the porous annulus. For the segment located at the bottom portion of inner wall, the flow rate is found to be higher, whereas the heat and mass transfer rates are higher when the source is placed near the middle of the inner wall. Further, the average Sherwood number increases with Lewis number, while for the average Nusselt number the effect is opposite. The average Nusselt number increases with radius ratio (λ); however, the average Sherwood number increases with radius ratio only up to λ = 5, and for λ > 5 , the average Sherwood number does not increase significantly.123 754 M. Sankar et al.

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Section: Numerical Technique and Code Validationmentioning

confidence: 99%

Double-Diffusive Convection from a Discrete Heat and Solute Source in a Vertical Porous Annulus

et al. 2011

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“…To consider the transfers interaction in the cylinder exits, the boundary conditions are as follows (see for instance Ameziani et al [12], Bennasrallah et al [21]): For the top surface (exit):…”

Section: Problem Formulationmentioning

confidence: 99%

“…4-7) and boundary conditions (Eqs. [8][9][10][11][12][13][14][15][16] are carried out using the following scaling:…”

Section: Problem Formulationmentioning

confidence: 99%

“…At t > 0, the corresponding spatial boundary conditions (11)(12)(13)(14) become respectively: If we name A the cylinder aspect ratio (i.e., A = R/H ), the lateral temperature (heated wall) is formulated by:…”

Section: Problem Formulationmentioning

confidence: 99%

“…It was also found that effects of aspect ratio become significant especially for higher values of amplitude, and both, flow strength as well as heat transfer, increase with Rayleigh number augmentation. The problem of unsteady natural convection heat transfer in a vertical, open-ended, porous cylinder heated laterally with a sinusoidal time variation of the temperature has been investigated by Ameziani et al [12]. They have found that the observed relative difference between sinusoidal and constant wall temperature is less than 5 %.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermal Enhancement in Storage Silos with Periodic Wall Heating

Himrane

Ameziani²,

Bouhadef³

et al. 2015

Arab J Sci Eng

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In this paper, unsteady natural convection problem in vertical, open-ended, porous cylinder has been numerically investigated to simulate the transient heat and mass convection in the grain storage in silos. The medium is the seat of a chemical reaction, and the enclosure lateral wall is submitted to a varying temperature profile. Time-dependent boundary temperature is presented as sinusoidal function which can approximate real weather conditions. In the case of constant temperature, a map diagram comprising several characteristic parameters such as Rayleigh number, aspect ratio, buoyancy ratio and lumped effective reaction rate of the two observed flow types, with and without fluid recirculation, was obtained. In order to approve that heat exchanges are dependent of reversal flow and control parameters, the phase diagrams connecting heat transfer (Nu) to the recirculation flow rate (Q r ) are proposed. The observed relative difference between sinusoidal and constant wall temperature increases with increasing Rayleigh number (Ra) and dimensionless temperature amplitudes (X A ), and it is particularly sensitive to the buoyancy ratio values (N) and the reaction rate (A k ). This difference passes from 18.7 % in the only thermal case to 8.15 % in the thermo-solutal case.

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Fully developed mixed convection of a binary fluid in a vertical porous channel

Alloui

Vasseur

2011

Can J Chem Eng

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This paper reports an analytical and numerical study of mixed convection heat and mass transfer of a binary fluid in a vertical parallel plate channel filled with a porous medium. The thermal conditions applied on the walls of the system are uniform heat fluxes. Both the cases of double-diffusion and Soret-induced convection are considered. The governing equations for the porous medium rely on Darcy's model. The governing parameters for the problem are the Rayleigh number, Ra, Peclet number, Pe, Lewis number, Le, buoyancy ratio, ϕ, aspect ratio of the channel A = L /H and the constant a (a = 0 for double diffusive convection and a = 1 for Soret induced convection). The resulting problem, in the limit of fully developed mixed convection, is solved analytically in closed form. A numerical solution of the full governing equations is demonstrated to be in good agreement with the analytical model. The temperature and velocity fields and the Nusselt and Sherwood numbers are obtained in terms of the governing parameters. The possible existence of reversed flows in the channel is discussed.

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Effect of the days scrolling on the natural convection in an open ended storage silo

Cited by 14 publications

References 26 publications

Double-Diffusive Convection from a Discrete Heat and Solute Source in a Vertical Porous Annulus

Double-Diffusive Convection from a Discrete Heat and Solute Source in a Vertical Porous Annulus

Thermal Enhancement in Storage Silos with Periodic Wall Heating

Fully developed mixed convection of a binary fluid in a vertical porous channel

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