Oblique fluid flow and convective heat transfer across a tube bank under uniform wall heat flux boundary conditions

This paper reports the experimental investigation of local convective heat transfer enhancement, flow friction and thermal performance factor behaviors in the tube fitted with the short helical tapes (SHTs) acting as decaying swirl flow generators. The tapes with three different helical tape angles (? = 90°, 135° and 180°) and three different channel numbers (N = 2, 3 and 4 channels) were tested under the uniform wall heat flux condition. The performance of each tape is compared with the performance of the plain tube subject to the same pumping power. The experimental results show that the heat transfer rates and friction factors of the tube with SHTs are respectively in range of 1.15 to 1.9 and 1.49 to 2.31 times of those in the plain, corresponding to thermal performances between 0.98 and 1.46. The correlations for Nusselt number (Nu) as a function of Reynolds number (Re), Prandtl number (Pr), helical tape angle (?) and the number of channel (N) are also developed.

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Convective heat transfer for a gaseous slip flow in micropipe and parallel-plate microchannel with uniform wall heat flux: effect of axial heat conduction

Indian Journal of Physics ◽

10.1007/s12648-017-1154-4 ◽

2017 ◽

Vol 92 (6) ◽

pp. 741-755 ◽

Cited By ~ 2

Author(s):

Y. Haddout ◽

E. Essaghir ◽

A. Oubarra ◽

J. Lahjomri

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Heat Conduction ◽

Convective Heat Transfer ◽

Parallel Plate ◽

Slip Flow ◽

Gaseous Slip Flow ◽

Uniform Wall ◽

Axial Heat ◽

Uniform Wall Heat Flux

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Heat Transfer From a Single Cylinder, Cylinders in Tandem, and Cylinders in the Entrance Region of a Tube Bank With a Uniform Heat Flux

Journal of Heat Transfer ◽

10.1115/1.3246934 ◽

1986 ◽

Vol 108 (2) ◽

pp. 386-391 ◽

Cited By ~ 14

Author(s):

J. W. Baughn ◽

M. J. Elderkin ◽

A. A. McKillop

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Wall Heat Flux ◽

Uniform Heat Flux ◽

Transfer Coefficients ◽

Tube Bank ◽

Single Cylinder ◽

Free Stream Turbulence ◽

Uniform Wall ◽

Uniform Wall Heat Flux

An experimental technique for obtaining a uniform wall heat flux has been used to determine the local heat transfer coefficients around a cylinder. Data are presented for a single cylinder, for cylinders in tandem, and cylinders located in the entrance of a tube bank. Results are compared to those of other studies with uniform wall heat flux. For the single cylinder, these are found to depend upon blockage, aspect ratio, and free-stream turbulence. For both inline and staggered tube arrangements, the heat transfer coefficient distribution depends on row location but appears to be nearly established by the third row.

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CFD study of Convective Heat Transfer of Water Flow Through Micro-Pipe with Mixed Constant Wall Temperature and Heat Flux Wall Boundary Conditions

CFD letters ◽

10.37934/cfdl.13.7.1326 ◽

2021 ◽

Vol 13 (7) ◽

pp. 13-26

Author(s):

Amjad Ali Pasha ◽

Meshal Nuwaym Al-Harbi ◽

Surfarazhussain S. Halkarni ◽

Nazrul Islam ◽

D. Siva Krishna Reddy ◽

...

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Boundary Conditions ◽

Convective Heat Transfer ◽

Convective Heat ◽

Constant Wall Temperature ◽

Constant Property ◽

Wall Boundary ◽

Wall Boundary Conditions ◽

Flow Through

The dissipation of heat in tiny engineering systems can be achieved with fluid flow through micro pipes. They have the advantage of less volume to large surface ratio convective heat transfer. There are deep-rooted analytical relations for convective heat transfer available for fluid flow through macro size pipes. But differences exist between the convective heat transfer for fluid flow through macro and micro pipes. Therefore, there is a good scope of work in micro convection heat transfer to study the mechanism of fundamental flow physics. There have been studies with either constant heat flux wall boundary conditions or constant wall temperature boundary conditions with constant and variable property flows. In this article, first, the numerical simulations are validated with the experimental data for 2D axisymmetric conventional pipe with pipe diameter of 8 mm is taken with laminar, steady, and single-phase water flows with constant wall heat flux boundary condition of 1 W/cm2. The computed Nusselt number is compared to the experimental results at different Reynolds numbers of 1350, 1600 and 1700. In the next study, three-dimensional micropipe laminar flow is studied numerically using water with an inlet velocity of 3 m/s and pipe diameter of 100 µm. The mixed wall boundary conditions with upper half pipe surface subjecting to constant wall temperature of 313 K and lower half surface subjecting to 100 W/cm2 are used in the simulations. The focus of research would be to consider the effect of temperature-dependent properties like thermal conductivity, viscosity, specific heat, and density (a combined effect we call it as variable properties) on micro-pipe flow characteristics like Nusselt number at mixed wall boundary conditions and compare it with the constant property flows. The conventional pipe showed no significant difference with variable and constant property flows with different Reynolds numbers. On contrary the flow through 3D micropipe shows that the Nusselt number with variable property flows is less as compared to the constant property flows.

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

Processes ◽

10.3390/pr9091668 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1668

Author(s):

Abdulrahim Kalendar ◽

Yousuf Alhendal ◽

Shafqat Hussain ◽

Patrick Oosthuizen

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Rayleigh Number ◽

Boundary Conditions ◽

Convective Heat Transfer ◽

Convective Heat ◽

Vertical Axis ◽

Surface Boundary ◽

Nusselt Numbers ◽

The Mean

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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