scholarly journals Convection Heat Transfer and Friction Factor of AL2O3/ Water Nanofluid Flows inside Circular Tube with Inserting Helical Tape.(Dept.M)

2020 ◽  
Vol 33 (4) ◽  
pp. 86-102
Author(s):  
Mohamed Saafan ◽  
Hesham Mostafa
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Circular Tube ◽  
Convection Heat Transfer ◽  
Convection Heat

Heat Transfer in Round Tube with Rectangular-Winglet Vortex Generators

2014 ◽  
Vol 931-932 ◽  
pp. 1173-1177
Author(s):  
Sompol Skullong ◽  
Pongjet Promvonge
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Thermal Performance ◽  
Circular Tube ◽  
Convection Heat Transfer ◽  
Test Tube ◽  
Tube Diameter ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
The One

Effect of 30° rectangular-winglet vortex generators (WVGs) mounted in the central core of a circular tube on convection heat transfer and friction loss is experimentally investigated in the present work. The rectangular-WVGs with two different winglet-height to tube-diameter ratios (called blockage ratio, BR = b/D = 0.1 and 0.2) and three winglet-pitch to tube-diameter ratios (PR=P/D=0.5, 1.0, and 1.5) are introduced. In the experiment, air at ambient condition is passed through the uniform heat-fluxed circular tube for Reynolds numbers (Re) in a range of 500024,000. The use of WVGs is to generate longitudinal vortex flows in the tube. The experimental results of heat transfer and pressure loss presented in terms of Nusselt number and friction factor are compared between the inserted and the smooth tubes. It is found that the BR and PR provide a significant effect on the thermal performance of the test tube. The results reveal that at smaller PR, the WVG with BR=0.2 provides the highest heat transfer and friction factor but the one with BR=0.2, PR=1.5 yields the best thermal performance.

Fluid flow and convection heat transfer in concentric and eccentric cylindrical annuli of different radii ratios for Taylor-Couette-Poiseuille flow

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110407
Author(s):  
Hosny Abou-Ziyan ◽  
Reda Ameen ◽  
Khairy Elsayed
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Friction Factor ◽  
Rotational Speed ◽  
Convection Heat Transfer ◽  
Tangential Velocity ◽  
Convection Heat ◽  
Eccentric Annuli

This paper presents the results of fluid flow and convection heat transfer in concentric and eccentric annuli between two cylinders using a three-dimensional computational fluid dynamics model. Effects of rotational speed ( n = 0, 150, 300, and 400 rpm) and eccentricity (ε = 0, 0.15, 0.3, 0.45, and 0.6) on axial and tangential velocity distribution, pressure drop and forced convection heat transfer are investigated for radii ratios (η) of 0.2, 0.4, 0.6, and 0.8, Reynolds number 2.0 × 103–1.236 × 105, Taylor number 1.47 × 106–1.6 × 1010, and Prandtl number 3.71–6.94. The parameters cover many applications, including rotary heat exchangers, mixers, agitators, etc. Nusselt numbers and friction factors for stationary and rotated concentric and eccentric annuli are correlated with four dimensionless numbers. The results revealed that when the speed of the inner cylinder increases from 0 to 400 rpm, the friction factor increases by 7.7%–103% for concentric and 8.2%–148% for eccentric annuli, whereas Nusselt number enhances by 37%–333% for concentric and 44%–340% for eccentric annuli. The radius ratio has a substantial effect on the heat transfer and pressure drop in annuli. The eccentricity enhances the heat transfer up to 12%, whereas its effect on the friction factor is not monotonic as it depends on Reynolds number, radii ratios, and rotational speed.

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