Conjugate natural convection in the roof cavity of heavy construction building during summer

Ben-Nakhi, Abdullatif; Mahmoud, M. A.

doi:10.1016/j.applthermaleng.2006.08.013

Cited by 14 publications

(8 citation statements)

References 19 publications

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“…3, and, as one may expect, the increase of Ra leads to increase in the total heat flux Nu sum . Unlike the previous study of natural convection inside roof enclosure during summer [2], a turbulent-flow model is employed in the current work. The temperature distribution across the sides of the cavity create buoyancy forces that are confronted by the cavity walls during summer, while the buoyancy forces created during winter force the flow away from the cavity walls.…”

Section: Resultsmentioning

confidence: 99%

“…Unlike the previous study of natural convection inside the roof enclosure during summer [2], cases with different outdoor surface temperatures are not considered in the current work. In other words, solar radiation is assumed to be similar on the three outdoor surfaces.…”

Section: Mathematical Modelmentioning

confidence: 89%

“…In the current work, the mesh quality of the numerical model was evaluated by analyzing the EquiAngle Skew, the EquiSize Skew and the aspect ratio of each cell within the domain. The reader should refer to [2] for further details on the employed mesh quality indices. In the present work, all requirements for high quality meshes are satisfied.…”

Section: Numerical Algorithmmentioning

confidence: 99%

“…Recently, several researchers numerically investigated laminar natural convection in building attic spaces. Ben-Nakhi and Mahmoud [2] summarized the previous works and presented results for conjugate laminar natural convection in the roof cavity of a heavy building construction under summer day boundary conditions. The roof cavity studied in the current work is similar to that studied by Ben-Nakhi and Mahmoud [2], but under winter day boundary conditions.…”

Section: Introductionmentioning

confidence: 98%

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Conjugate turbulent natural convection in the roof enclosure of a heavy construction building during winter

Ben-Nakhi

Mahmoud

2008

Applied Thermal Engineering

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Section: Resultsmentioning

confidence: 99%

Section: Mathematical Modelmentioning

confidence: 89%

Section: Numerical Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Conjugate turbulent natural convection in the roof enclosure of a heavy construction building during winter

Ben-Nakhi

Mahmoud

2008

Applied Thermal Engineering

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“…Das and Reddy [6] presented a study of natural convection flow in a square enclosure with a centered internal conducting square block both of which are given an inclination angle. Ben-Nakhi and Mahmoud [7] studied conjugate natural convection inside a building attic in the shape of rectangular enclosure bounded by realistic walls made from composite construction materials under summer day boundary conditions. Their results show that the values of Rayleigh number and the aspect ratio have significant effect on the temperature and stream function contours within the enclosure.…”

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confidence: 99%

Effect of Magnetic Field and Wall Conductivity on Conjugate Natural Convection in a Square Enclosure

2014

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Steady, laminar, conjugate natural convection flow in the presence of a magnetic field in a square enclosure is considered. The left vertical wall of the enclosure is thick with a finite thermal conductivity, while the other three walls are taken to be of zero thickness. The enclosure is filed with liquid gallium and subjected to horizontal temperature gradient: the vertical boundaries are isothermal at different temperatures, whereas the remaining walls are adiabatic. Finite volume method is used to solve the dimensionless governing equations. The physical problem depends on seven parameters: Rayleigh number (500 ≤ Ra ≤ 10 6 ), the Prandtl number (Pr = 0.020), the wall to fluid thermal conductivity ratio (0.1 ≤ Kr ≤ 10), wall thickness (D = 0.2), the Hartmann number (50 ≤ Ha ≤ 200), the inclination angle of the magnetic field (φ = 0 • , 45 • or 90 • ) and the wall to fluid thermal diffusivity ratio (α * = 1). The main focus of the study is on examining the effect of both inclination angle and Hartmann numbers on fluid flow and heat transfer. The effect of Rayleigh number and conduction in the left wall is also considered. The obtained results, in the absence of a magnetic field, show that natural convection can be strengthened by the increase of both Rayleigh number and conductivity ratio, because of the increase of the effective temperature difference driving the flow. For poor conducting wall (Kr = 0.1), where the solid part is an insulated material and the thermal resistance is more important, the average Nusselt numberis approximately constant and having low values comparing with equal (Kr = 1) and high (Kr = 10) conducting wall, indicating that most of heat transfer is by heat conduction. The interface temperature is found to be quite non-uniform, especially for high Ra and Kr. This non-uniformity tends to make the flow pattern in the enclosure asymmetric. In the presence of a magnetic field, the results show that for a given Ra, as the value of Hartmann number increases, convection is suppressed progressively and the rate of heat transfer is reduced in the enclosure. Convection mechanism is also affected by the direction of the magnetic field. It is found that the rate of convection heat transfer is more reduced with the x direction of the magnetic field (inclination angle φ = 0 • ). Also the results show that for poor conducting wall (Kr = 0.1), where the convection is dominated by heat conduction, the presence of a magnetic field is not important and its effect in this case can be neglected.

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Improving thermal performance of the roof enclosure of heavy construction buildings

Ben-Nakhi

Mahmoud

et al. 2008

Applied Energy

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Conjugate natural convection in the roof cavity of heavy construction building during summer

Cited by 14 publications

References 19 publications

Conjugate turbulent natural convection in the roof enclosure of a heavy construction building during winter

Conjugate turbulent natural convection in the roof enclosure of a heavy construction building during winter

Effect of Magnetic Field and Wall Conductivity on Conjugate Natural Convection in a Square Enclosure

Improving thermal performance of the roof enclosure of heavy construction buildings

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