Heat Transfer Enhancement of TiO2/Water Nanofluid at Laminar and Turbulent Flows: A Numerical Approach for Evaluating the Effect of Nanoparticle Loadings

Heat transfer rate and pressure drop of turbulent flows of water in a smooth-wall tube and five corrugated tubes at Reynolds numbers between 7,500 and 50,000 are studied using the commercial software FLUENT. The corrugated tube is constructed by placing protruded ridges evenly along a tube. Depending on the different design of corrugated tubes, our numerical simulation results show that the use of corrugated tubes can improve heat transfer rate by a factor of 1.5 to 2 at Reynolds numbers between 7,500 and 12,000 when compared to a smooth-wall tube. However, the rate of enhancement gradually decreases to a factor of 1.1 to 1.5 as flow Reynolds number increases to 50,000. We further studied the pressure drop and friction factors of the corrugated tube. For the corrugated tube with the highest heat transfer enhancement, we found the pressure drop increases by a factor of 3 to 4 compared to a smooth-wall tube, while the friction factor increases by a factor of 3.5 to 4.4. These findings can be very useful in the design of more efficient heat exchangers.

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Numerical Investigation and Thermal Transfer on a Wall Corrugated without and with Artificial Roughness

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.392.189 ◽

2019 ◽

Vol 392 ◽

pp. 189-199

Author(s):

Rabia Ferhat ◽

Ahmed Zine Dinne Dellil ◽

M. Kamal Hamidou

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Heat Exchange ◽

Heat Transfer Enhancement ◽

Turbulent Flows ◽

Exchange Process ◽

Three Dimensional ◽

Artificial Roughness ◽

Transfer Enhancement ◽

Corrugated Channel

The objective of this study is to give the designer an appreciation of the heat transfer enhancement in turbulent flows through corrugated channels in a heat plate exchanger. Precisely, the influence of a new technic named the artificial roughness is probed on corrugated walls, with their variable wall amplitudes for assessing the effectiveness of the heat exchange. For that purpose, a numerical simulation approach is adopted. The rectangular, triangular, trapezoidal and sinusoidal corrugated wall and artificial roughness wall shapes are investigated, in order to determine the optimal wall profile resulting in significance increase in the heat exchange process with a minimum friction loss. The numerical results are presented in the form of isotherms, streamlines, contour, Nusselt number (Nu) and friction coefficient (Cf) using commercial software ANSYS- Fluent where the Reynolds number is in the range from 3 000 to 12 000. Our simulations reveal that the sinusoidal-corrugated channel has the highest heat transfer enhancement followed by rectangular, triangular and trapezoidal-corrugated channel. In addition, introduction of artificial roughness in the wavy channel induces stronger secondary flow which makes the flow three-dimensional and improve the heat transfer by a maximum 40% at a Reynolds number equal to 12 000. This may indicate benefits for designing heat plate compact exchangers capable of higher performances in the turbulent flow regimes.

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A fundamental study of heat transfer enhancement by controlling the internal structure of turbulent flows.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.53.1298 ◽

1987 ◽

Vol 53 (488) ◽

pp. 1298-1306

Author(s):

Hideo YOSHIDA ◽

Takaaki FURUYA ◽

Ryozo ECHIGO

Keyword(s):

Heat Transfer ◽

Heat Transfer Enhancement ◽

Internal Structure ◽

Turbulent Flows ◽

Transfer Enhancement ◽

Fundamental Study

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Computational Analysis of Heat Transfer Enhancement in Square Ducts With V-Shaped Ribs: Turbine Blade Cooling

Journal of Heat Transfer ◽

10.1115/1.1865220 ◽

2005 ◽

Vol 127 (4) ◽

pp. 425-433 ◽

Cited By ~ 24

Author(s):

R. Jia ◽

B. Sunde´n ◽

M. Faghri

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Heat Transfer Enhancement ◽

Turbulence Modeling ◽

Experimental Studies ◽

Numerical Approach ◽

Navier Stokes ◽

Transfer Enhancement ◽

Transfer Coefficients ◽

Sampling Points

Experimental studies have revealed that both downstream and upstream pointing V-shaped ribs result in more heat transfer enhancement than transverse straight ribs in ducts. However, based on the available experimental results, contradiction exists whether the upstream or the downstream pointing V-shaped ribs orientation is superior for better enhancement in heat transfer. Further investigations are thus needed concerning the heat transfer and fluid flow phenomena in ducts with V-shaped ribs to clarify this. In the present investigation a numerical approach is taken and the heat and fluid flow is numerically simulated by a multi-block parallel 3D solver. For turbulence modeling, the v2¯ f-kε model is employed but results from previous EASM calculations are also considered in analyzing and attempting to understand the various experimental data. Large eddy simulations (LES) are also carried to evaluate the accuracy and reliability of the results of Reynolds-averaged Navier-Stokes (RANS) methods and to understand the underlying physical phenomena. It is suggested that the discrepancy between the various experiments most probably is due to the measurement methods, or the number of sampling points. With the TC (thermocouples) technique, a few sampling points are not sufficient to represent the heat transfer behavior in V-shaped ribs, due to the uneven distribution of the heat transfer coefficients.

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