scholarly journals Numerical investigation of laminar forced convection heat transfer in rectangular channels with different block geometries using nano-fluids

2017 ◽  
Vol 21 (5) ◽  
pp. 2129-2138 ◽  
Author(s):  
Saeed Foroutani ◽  
Alireza Rahbari
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Forced Convection ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Triangular Block

This research investigates the laminar steady-forced convection heat transfer of a Cu-water nanofluid in a 2-D horizontal channel with different block geometries attached to the bottom wall. The block geometries assumed in this research are triangular and curve blocks. The governing equations associated with the required boundary conditions are solved using finite volume method based on the SIMPLE technique and the effects of Reynolds number, nanofluid volume fraction, block geometry, and the numbers of blocks on the local and average Nusselt numbers are explored. The obtained results show that nanoparticles can effectively enhance the heat transfer in a channel. Furthermore, the local and average Nusselt number distribution is strongly dependent on the block geometry. As observed, the heat transfer augments with the increase in the Reynolds number and nanofluid volume fraction for both block geometries. It is also concluded that the average Nusselt number of the curve block is higher than that of the triangular block for different Reynolds numbers which declares the importance of the block geometry in the heat transfer enhancement.

scholarly journals Investigation Of Forced Convection Heat Transfer From A Heater Mounted Ina Cavity Wall Using Various Nanofluids

2019 ◽  
Vol 128 ◽  
pp. 07002
Author(s):  
R. Kanna ◽  
Sayed Sayeed Ahmad ◽  
P. Venkata Reddy ◽  
Chithirai Pon Selvan ◽  
Tale ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Forced Convection ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Cavity Wall ◽  
Main Stream ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

Forced convection heat transfer from heater mounted in a cavity wall is investigated to reveal the relation among nanofluid properties. The base fluid is considered as water. The present study is focused on forced convection heat transfer from square heater subject to inflow and outflow inside a squarecavity. The interesting physics will be reported in connection with volume fraction, Reynolds number and nanomaterial properties. It is found that for a particular Reynolds number when nanomaterial is introduced the local heat transfer is increased. The wall attached vortex attributes a constant Nusselt number. It is also noticed that when the heater wall is subject to combination of vortex and main stream fluid results high Nusselt number than heat transfer due to wall attached vortices. Nanofluid results high Nusselt number for the same Reynolds number.

Forced convection heat transfer of Ag–MgO/water micropolar hybrid nanofluid inside a stairway channel

2021 ◽  
pp. 2150147
Author(s):  
Hanif Heidari ◽  
Rasul Mohebbi ◽  
Amir Kazemi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Forced Convection ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Hybrid Nanofluid ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Micropolar Nanofluid

In this paper, the forced convection heat transfer of Ag–MgO/water hybrid micropolar nanofluid in a channel is studied numerically which the top wall of channel is smooth and bottom of it is in stairway form. The lattice Boltzmann method (LBM) is used for solving the fluid flow and heat transfer equations. The effects of Reynolds numbers ([Formula: see text]–400), volume fraction of nanofluid ([Formula: see text], 0.01 and 0.02) and stairway aspect ratio ([Formula: see text], 0.2 and 0.3) on the velocity, temperature and local and average Nusselt number profiles are investigated. The results show that by incrementing the Reynolds number and solid volume fraction and decreasing the [Formula: see text]/[Formula: see text] simultaneously, the average Nusselt number increases.

Numerical Investigation of Forced Convection Heat Transfer from Offset Square Cylinders Placed in a Three Dimensional Confined Channel

2015 ◽  
Vol 813-814 ◽  
pp. 729-735 ◽  
Author(s):  
Paulraj Maheandera Prabu ◽  
Mahadevan Sivasubramanian ◽  
P. Rajesh Kanna ◽  
M. Uthayakumar ◽  
K.P. Padmanaban
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Flow Simulation ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Square Cylinders ◽  
Confined Channel

Abstract-Flow over two offset square cylinders in a confined channel is simulated for different Reynoldsnumber to reveal the forced convection heat transfer from the heated square cylinders to the ambientfluid. The bottom of the cylinder is maintained at constant temperature. The distance between thecylinder in normal direction as well as transverse direction are fixed as 2d and the blockage ratio is fixedas 0.167. Heat transfer from the cylinders to the ambient fluid as well as conducted within solid wallthrough conjugate interface boundary investigated in connection with Reynolds number are reportedfor both steady and periodic flow. Simulation is carried out for Reynolds number varies from 10 to100 for the fluid as air with Prandtl number as 0.71. The isotherm contours, local Nusselt number andaverage Nusselt number are reported for various Reynolds number. The stagnation zone results higherNusselt number than remaining walls and rear wall results lowest Nusselt number. The downstreamcylinder results higher Nusselt number than the upstream cylinder. The top and bottom surfaceNusselt number from upstream and downstream cylinder are not analogous to single cylinder placed ina channel.

On the Nusselt Number for H2 Heat Transfer in Rectangular Ducts of Large Aspect Ratios

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Forced Convection ◽  
Parallel Plate ◽  
Convection Heat Transfer ◽  
Analytic Method ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Aspect Ratios

The H1 and H2 forced convection heat transfer in rectangular ducts are studied using an accurate, analytic method. It is confirmed that, as the aspect ratio tends to infinity, the Nusselt number for the H2 case approaches 2.9162, much lower than the parallel plate value of 8.2353 attained by the H1 case. The controversy about the H2 limit is thus settled. An explanation of the behavior is suggested.

scholarly journals Prediction of Natural Convection Heat Transfer Phenomena of Nanofluids in Corrugated Annulus

2020 ◽  
Author(s):  
Sattar Aljobair ◽  
Akeel Abdullah Mohammed ◽  
Israa Alesbe
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Outer Cylinder ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat

Abstract The natural convection heat transfer and fluid flow characteristic of water based Al2O3 nano-fluids in a symmetrical and unsymmetrical corrugated annulus enclosure has been studied numerically using CFD. The inner cylinder is heated isothermally while the outer cylinder is kept constant cold temperature. The study includes eight models of corrugated annulus enclosure with constant aspect ratio of 1.5. The governing equations of fluid motion and heat transfer are solved using stream-vorticity formulation in curvilinear coordinates. The range of solid volume fractions of nanoparticles extends from PHI=0 to 0.25, and Rayleigh number varies from 104 to 107. Streamlines, isotherms, local and average Nusselt number of inner and outer cylinder has been investigated in this study. Sixty-four correlations have been deduced for the average Nusselt number for the inner and outer cylinders as a function of Rayleigh number have been deduced for eight models and five values of volume fraction of nano particles with an accuracy range 6-12 %. The results show that, the average heat transfer rate increases significantly as particle volume fraction and Rayleigh number increase. Also, increase the number of undulations in unsymmetrical annuli reduces the heat transfer rates which remain higher than that in symmetrical annuli. There is no remarkable change in isotherms contour with increase of volume fraction of nanofluid.

Experimental Study of Forced Convection From Isothermal Circular and Square Cylinders and Toroids

1997 ◽  
Vol 119 (1) ◽  
pp. 70-79 ◽  
Author(s):  
G. Refai Ahmed ◽  
M. M. Yovanovich
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Reynolds Numbers ◽  
Empirical Models ◽  
Experimental Program ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Wide Range

Experimental studies of forced convection heat transfer from different body shapes were conducted to determine the effects of Reynolds number and different characteristic body lengths on the area-averaged Nusselt number. Although the bodies differed significantly in their shapes, they had approximately the same total surface area, A = 11,304 mm2 ± 5%. This ensured that for a given free stream velocity and total heat transfer rate all bodies had similar trends for the relationship of Nusselt and Reynolds numbers. The experimental program range was conducted in the Reynolds number range 104≤ReA≤105 and Prandtl number 0.71. Finally, the empirical models for forced convection heat transfer were developed. These empirical models were valid for a wide range of Reynolds numbers 0≤ReA≤105. The present experimental correlations were compared with available correlation equations and experimental data. These comparisons show very good agreement.

An Experimental Study on Forced Convection Heat Transfer From Flush-Mounted Discrete Heat Sources

1999 ◽  
Vol 121 (2) ◽  
pp. 326-332 ◽  
Author(s):  
C. P. Tso ◽  
G. P. Xu ◽  
K. W. Tou
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Source ◽  
Forced Convection ◽  
Rectangular Channel ◽  
Convection Heat Transfer ◽  
Channel Height ◽  
Air Cooling ◽  
Convection Heat ◽  
Forced Convection Heat Transfer

Experiments have been performed using water to determine the single-phase forced convection heat transfer from in-line four simulated electronic chips, which are flush-mounted to one wall of a vertical rectangular channel. The effects of the most influential geometric parameters on heat transfer including chip number, and channel height are tested. The channel height is varied over values of 0.5, 0.7, and 1.0 times the heat source length. The heat flux is set at the three values of 5 W/cm2, 10 W/cm2, and 20 W/cm2, and the Reynolds number based on the heat source length ranges from 6 × 102 to 8 × 104. Transition Reynolds numbers are deduced from the heat transfer data. The experimental results indicate that the heat transfer coefficient is affected strongly by the number of chips and the Reynolds number and weakly by the channel height. Finally, the present results from liquid-cooling are compared with other results from air-cooling, and Prandtl number scaling between air and water is investigated.

Simplified Analytical Models for Forced Convection Heat Transfer From Cuboids of Arbitrary Shape

2000 ◽  
Vol 123 (3) ◽  
pp. 182-188 ◽  
Author(s):  
J. R. Culham ◽  
M. M. Yovanovich ◽  
P. Teertstra ◽  
C.-S. Wang ◽  
G. Refai-Ahmed ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Analytical Models ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Aspect Ratios ◽  
Diffusive Limit

Three analytical models are presented for determining laminar, forced convection heat transfer from isothermal cuboids. The models can be used over a range of Reynolds number, including at the diffusive limit where the Reynolds number goes to zero, and for a range of cuboid aspect ratios from a cube to a flat plate. The models provide a simple, convenient method for calculating an average Nusselt number based on cuboid dimensions, thermophysical properties and the approach velocity. Both the cuboid and the equivalent flat plate models are strongly dependent upon the flow path length which is bounded between two easily calculated limits. In comparisons with numerical simulations, the models are shown to be within ±6 percent over the range of 0⩽ReA⩽5000 and aspect ratios between 0 and 1.

scholarly journals Research on heat transfer characteristics of flow in tube of water-based nanofluids

2020 ◽  
pp. 301-301
Author(s):  
Pengfei Chen ◽  
Zhuangzhuang Jia ◽  
Zhumei Luo ◽  
Shan Qing ◽  
Xiaoyan Huang
Keyword(s):  
Heat Transfer ◽  
Entropy Production ◽  
Forced Convection ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Transfer Entropy ◽  
Hybrid Nanofluid ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Water Based

In this paper, the characteristics of forced convection heat transfer in water-based nanofluids are studied by means of experimental and theoretical analysis. Nusselt number of nanofluids were calculated by changing the volume fraction and the type of nanoparticles in the tube. The effects of Reynolds number and the volume fraction of nanoparticles on the forced convection heat transfer were studied. An exergy analytical model was established for the laminar heat transfer of nanofluid under the condition of constant heat flow. At the same Reynolds condition, the friction entropy production of the flow and heat transfer process in the tube increases with the addition of nanoparticles, and the heat transfer entropy production decreases at the same time. However, the magnitude of friction entropy production is only 10-6, which is negligible compared with the heat transfer entropy production. Therefore, in general, the loss of nanofluids is lower than that of pure water; for nanofluids, the exergy loss of hybrid nanofluid is lower than that of single nanofluid at the same volume fraction.

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