Numerical Study of Enhanced Heat Transfer and Flow of Water-glycol Mixture in Transversely Ribbed Circular Tubes

2010 ◽  
Author(s):  
H. X. Zhao ◽  
J. T. Han ◽  
Z. T. Yu ◽  
L. Shao ◽  
M. X. Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Enhanced Heat Transfer ◽  
Circular Tubes

An Attempt to Uncouple the Effect of Coriolis and Buoyancy Forces Experimentally on Heat Transfer in Smooth Circular Tubes That Rotate in the Orthogonal Mode

1992 ◽  
Vol 114 (4) ◽  
pp. 858-864 ◽  
Author(s):  
W. D. Morris ◽  
R. Salemi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Circular Tube ◽  
Leading Edge ◽  
Combined Effect ◽  
Enhanced Heat Transfer ◽  
Coriolis Forces ◽  
Circular Tubes ◽  
Buoyancy Forces

This paper reports the results of an experimental investigation of the combined effect of Coriolis and buoyancy forces enforced convection in a circular tube that rotates about an axis orthogonal to its centerline. The experiment has been deliberately designed to minimize the effect of circumferential conduction in the tube walls by using material of relatively low thermal conductivity. A new correlating parameter for uncoupling the effect of Coriolis forces from centripetal buoyancy is proposed for the trailing and leading edges of the tube. It is demonstrated that enhanced heat transfer on the trailing edge occurs as a result of rotation. On the leading edge significant reductions in heat transfer compared to the zero rotation case can occur, but with possible recovery at high rotational speeds.

Numerical investigation of heat transfer and hydrodynamics for in-line drop-shaped tubes bundle

2020 ◽  
pp. 42-59
Author(s):  
R. Deeb ◽  
◽  
A.V. Kolotvin ◽  
Keyword(s):  
Heat Transfer ◽  
Software Package ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Equivalent Diameter ◽  
Heat Transfer Characteristics ◽  
Circular Tubes ◽  
The Third ◽  
Flow And Heat Transfer

A numerical study using the software package ANSYS has been conducted to investigate fluid flow and heat transfer characteristics for in-line drop-shaped and circular tubes bundles in crossflow. Reynolds number based on equivalent diameter varied in range of 3x103 ≤ Re ≤ 18.7x103. The longitudinal spacing SL= 37, 46.25 mm, while the transversal spacing ST =37 mm. A mathematical and numerical model has been developed for numerical evaluation of heat transfer and hydrodynamic of a studied bundles. The distribution of the pressure coefficient over a half surface of the circular and drop-shaped tubes of the third row was obtained. Correlations of the average Nusselt number and the friction coefficient for the studied bundles in terms of Re were presented. Results showed that pressure coefficient and heat transfer of drop-shaped tubes depend on position of tubes in tubes bundle. The thermal–hydraulic performance of the drop-shaped tubes bundle is about 1,45~ 2,01 и 1,45~ 2,01 times greater than the circular one for SL= 37, 46.25 mm, respectively.

Experimental and Numerical Study on Enhanced Heat Transfer of Solid-Liquid PCM by Ultrasonic Wave

2006 ◽  
Vol 326-328 ◽  
pp. 1145-1148
Author(s):  
Ho Dong Yang ◽  
Yool Kwon Oh
Keyword(s):  
Heat Transfer ◽  
Acoustic Pressure ◽  
Numerical Study ◽  
Acoustic Streaming ◽  
Melting Process ◽  
Oscillating Flow ◽  
Enhancement Ratio ◽  
Ultrasonic Vibrations ◽  
Enhanced Heat Transfer ◽  
Solid Liquid

The present study is investigated the causes of enhanced heat transfer during the melting process of solid-liquid PCM (Phase Change Material) using an ultrasonic vibration. Paraffin (noctadecane) was selected as a PCM and experimental studies were performed as following. Heat transfer coefficient and enhancement ratio of heat transfer was measured, acoustic streaming induced by ultrasonic waves observed using a PIV (Particle Image Velocimetry) and thermally oscillating flow phenomenon observed using an infrared thermal camera during the melting process. For the numerical study, a coupled FE-BEM (Finite Element-Boundary Element Method) was applied to investigate acoustic pressure occurred by acoustic streaming in a medium. And then, the profiles of pressure variation compared with the enhancement ratio of heat transfer. The results of this study revealed that ultrasonic vibrations accompanied the effects like acoustic streaming and thermally oscillating flow. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. Also, as the acoustic pressure occurred by acoustic streaming increases, the higher enhancement ratio of heat transfer is obtained.

An Attempt to Experimentally Uncouple the Effect of Coriolis and Buoyancy Forces on Heat Transfer in Smooth Circular Tubes Which Rotate in the Orthogonal Mode

1991 ◽  
Author(s):  
W. D. Morris ◽  
R. Salemi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Forced Convection ◽  
Circular Tube ◽  
Leading Edge ◽  
Enhanced Heat Transfer ◽  
Coriolis Forces ◽  
Circular Tubes ◽  
Buoyancy Forces

This paper reports the results of an experimental investigation of the combined effect of Coriolis and buoyancy forces on forced convection in a circular tube which rotates about an axis orthogonal to its centre line. The experiment has been deliberately designed to minimise the effect of circumferential conduction in the tube walls by using material of relatively low thermal conductivity. A new correlating parameter for uncoupling the effect of Coriolis forces from centripetal buoyancy is proposed for the trailing and leading edges of the tube. It is demonstrated that enhanced heat transfer on the trailing edge occurs as a result of rotation. On the leading edge significant reductions in heat transfer compared to the zero rotation case can occur but with possible recovery at high rotational speeds.

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