Experimental free convection heat transfer from inclined square cylinders

Ali, Mohamed

doi:10.1007/s00231-016-1881-7

Cited by 8 publications

(13 citation statements)

References 37 publications

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“…This indicates that as the axial distance along the cylinder increases, the local heat transfer decreases, or at most, slightly increases. This confirms that the mode of heat transfer is mostly laminar [22,23], followed by transition, as confirmed in Figure 4b. shows the effect of accumulated TBL, which tends to degrade the heat transfer of cylinder number 1 compared to number 2, and the result is making its profile lower than that of number 2.…”

Section: Resultssupporting

confidence: 82%

Tilt Angle Effect on Natural Convection Heat Transfer from an Inclined Array of Square Cylinders

Al-Suhaibani,

Ali,

Almuzaiqer

2024

Energies

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Natural convection heat transfer from an inclined array of square cross-section cylinders is experimentally studied. Three cylinders of side length D = 0.02 m and 1 m length are used to form the inclined array. Three-cylinder axis inclination angles to the horizontal of 30°, 45°, and 60° are considered. The cylinders are heated using an internal heating element of constant heat flux. Surface temperatures are measured along the three surfaces of each cylinder; upper, lower, and the front side at nine points spaced evenly by 10 cm. The local circumference average temperature is obtained at each point. Four center-to-center distances to side length S/D = 1.25, 1.75, 2.25, and 2.75 are used. Local Nusselt numbers and the modified Rayleigh numbers are obtained for each cylinder at each circumference averaged temperature point. Results show that the lower cylinder heat transfer is least affected by the array compared to that of its single one followed by the middle and the upper cylinder for all S/D and the inclination angles used. The Nusselt number is degraded from that of the single cylinder at a small S/D and that degradation decreases as the S/D increases for all angles. It is observed that the Nusselt number enhances at the small cylinder axis tilt angle of 30°, followed by 45°, and 60°, especially at high modified Rayleigh numbers. New novel general empirical correlations for Nusselt numbers are obtained for each S/D using the cylinder axis tilt angle, the modified Rayleigh numbers, and the cylinder number in the array as parameters. A new general correlation is obtained for the array using the modified Rayleigh number, S/D, the cylinder axis tilt angle, and the cylinder sequential order number as parameters. These new correlations will help any engineering applications using such a configuration of the array.

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Section: Resultssupporting

confidence: 82%

Tilt Angle Effect on Natural Convection Heat Transfer from an Inclined Array of Square Cylinders

Al-Suhaibani,

Ali,

Almuzaiqer

2024

Energies

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“…Representative results for this condition are shown in Figure 4. It can be seen that there is good agreement on the range of accuracy between the correlation equation and experimental results obtained by Ali [30] and the present numerical results. We believe that the differences between the mean Nusselt numbers obtained by Ali [30] and the present numerical results at higher values of Rayleigh numbers are due to the uncertainty in Ali's [30] results, which was in the range ±15%.…”

Section: Validationsupporting

confidence: 87%

“…The model was previously validated by Kalendar and Oosthuizen [29] who compared numerical, correlation equation, and experimental results for constant temperature boundary conditions and found that they exhibited fairly good agreement. Further validation was carried out using the correlation equation and experimental results obtained by Ali [30] for a square cylinder in air with constant heat flux boundary conditions of w/h = 0.08 and at angles of 60 • (30 • from the horizontal) and 45 • where the bottom and top surfaces were adiabatic. Representative results for this condition are shown in Figure 4.…”

Section: Validationmentioning

confidence: 99%

“…In addition, the authors also studied naturally occurring convective heat transfer from inclined square cylinders with the top surfaces exposed with constant wall heat flux boundary conditions, and determined the effects of dimensionless parameter w/h ratios in the range 0.5 to 1, modified Rayleigh numbers in the range 1 × 10 3 to 1 × 10 6 , and inclination angles from 0 • to 180 • on the mean Nusselt number for different surfaces of square cylinders in the laminar flow region. Ali [30] investigated convection heat transfer in the region of laminar flow and the transition flow regions of inclined square cylinders with constant heat flux boundary conditions. Five different square cylinders were studied with aspect ratios, w/h, of 0.08, 0.07, 0.06, 0.04, and 0.025 at angles of 30 • , 45 • , and 60 • from the horizontal axis, and a correlation equation for average and local Nusselt numbers was developed.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Inclination on Natural Convective Heat Transfer from a Slender Cuboid

et al. 2021

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A numerical study was undertaken of the naturally occurring laminar convective heat transfer from a slender cuboid with a relatively narrow cross-section (square) and an exposed top surface. The cuboid was perpendicularly placed on an adiabatic flat base plate and two types of surface boundary conditions were considered. The slender cuboid was inclined relative to the vertical axis at angles ranging from 0 to 180 degrees. The flow was considered symmetrical along the vertical axis of the slender cuboid. The equations governing the system were numerically solved in terms of dimensionless variables using FLUENT software. From the results obtained, mean Nusselt numbers over the slender cuboid were calculated using parameters such as: the Rayleigh number for heat flux, Ra*; the Rayleigh number, Ra; the slender cuboid dimensionless width, i.e., the ratio of the width to the height of the heated slender cuboid, W = w/h; and the position of the slender cuboid relative to the vertical, φ. Simulation results were produced for the boundary conditions of constant temperature, constant heat flux, and for Pr = 0.7. The effects of these parameters on the mean Nusselt number for the combined and for the individual surfaces of the slender cuboid are presented and the mean Nusselt numbers are correlated.

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“…Their results for the average Nusselt number and for inclination angle range from 0 to 180 ∘ were correlated as Nu (32) where W is the width ratio (width/height). Experimental study has been made on local and averaged natural convection heat transfer from inclined square cylinders in air at 30 ∘ ,45 ∘ , and 60 ∘ inclination angle to the horizontal by Ali [24]. His results showed that the correlation obtained for each inclination angle indicated that the natural convection has a weak dependence on the inclination angle; therefore, overall correlations were obtained to cover all cylinders at all inclination angles for laminar regime: one for local laminar profiles (Eq.…”

Section: Cylinders Of Different Cross Sections In Free Convectionmentioning

confidence: 99%

Free Convection Heat Transfer from Different Objects

Ali¹,

Sadek²

2018

Heat Transfer - Models, Methods and Applications

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Heat transfer by natural convection phenomenon has been studied by diverse researchers for several geometries and different boundary conditions. Different approaches were used such as numerical, analytical, and experimental approaches. In this chapter, we are going to review the most common published research on object shapes in natural convection heat transfer with their obtained numerical, semiempirical, and/or experimental correlations for the last two decades. These correlations are very important for engineering applications. This chapter will be stressed on cylinders in different orientations with cross sections such as circular, square, triangular, vertical, and horizontal coils and array of cylinders of different cross sections.

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Experimental free convection heat transfer from inclined square cylinders

Cited by 8 publications

References 37 publications

Tilt Angle Effect on Natural Convection Heat Transfer from an Inclined Array of Square Cylinders

Tilt Angle Effect on Natural Convection Heat Transfer from an Inclined Array of Square Cylinders

The Effect of Inclination on Natural Convective Heat Transfer from a Slender Cuboid

Free Convection Heat Transfer from Different Objects

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