To find the reasons of heat transfer enhancement of a laminar convective heat transfer process in a channel at a uniform heat flux boundary when a pair of longitudinal vortex generators (VGs) is mounted on the bottom wall, the laminar convective heat transfer process in the channel is investigated numerically in a frame built up by the convective transport equation of the heat flux. The results show that longitudinal vortices greatly increase the local convection contribution terms that determine the local intensity of the convective transport of the heat flux component in the span direction, and that the increased local contribution terms intensify the local convective transport of the heat flux component in the same direction. This process increases the convection contribution terms that determine the convective transports of the heat flux components in the main stream direction and in the normal direction of the channel walls. The increase in these convection contribution terms results in an enhancement of the convective heat transfer ability on the channel walls, and then, the heat transfer is enhanced by longitudinal vortices. When the span-averaged characteristic is numerically counted, longitudinal vortices are found to have no contribution on the span-averaged convective transport of the heat flux in the span direction.

References

1.
Eibeck
,
P. A.
, and
Eaton
,
J. K.
,
1986
, “
The Effects of Longitudinal Vortices Embedded in a Turbulent Boundary Layer on Momentum and Thermal Transport
,”
Eighth International Heat Transfer Conference
, San Francisco, CA, Aug. 17–22, pp.
1115
1120
.
2.
Eibeck
,
P. A.
, and
Eaton
,
J. K.
,
1987
, “
Heat Transfer Effects of a Longitudinal Vortex Embedded in a Turbulent Boundary Layer
,”
ASME J. Heat Transfer
,
109
(1), pp.
16
24
.
3.
Russell
,
C. M. B.
,
1986
, “
The Development of a High Performance Heat Transfer Surface
,”
Eighth International Heat Transfer Conference
, San Francisco, CA, Aug. 17–22, pp.
843
855
.
4.
Pauley
,
W. R.
, and
Eaton
,
J. K.
,
1987
, “
The Effect of Embedded Longitudinal Vortex Pairs on Turbulent Boundary Layer Heat Transfer
,” Report No. DOE/ER/13081-T2.
5.
Tiggebeck
,
S.
,
Mitra
,
N. K.
, and
Fiebig
,
M.
,
1994
, “
Comparison of Wing-Type Vortex Generators for Heat Transfer Enhancement in Channel Flows
,”
ASME J. Heat Transfer
,
116
(
4
), pp.
880
885
.
6.
Fiebig
,
M.
, Kallweit, P., and Mitra, N. K.,
1986
, “
Wing Type Vortex Generators for Heat Transfer Enhancement
,”
Eighth International Heat Transfer Conference
, San Francisco, CA, Aug. 17–22, pp. 2909–2913.
7.
Jang
,
J. Y.
,
Hsu
,
L. F.
, and
Leu
,
J. S.
,
2013
, “
Optimization of the Span Angle and Location of Vortex Generators in a Plate-Fin and Tube Heat Exchanger
,”
Int. J. Heat Mass Transfer
,
67
, pp.
432
444
.
8.
Wang
,
Q.
,
Chen
,
Q.
,
Wang
,
L.
, Zeng, M., Huang, Y., and Xiao, Z.,
2007
, “
Experimental Study of Heat Transfer Enhancement in Narrow Rectangular Channel With Longitudinal Vortex Generators
,”
Nucl. Eng. Des.
,
237
(
7
), pp.
686
693
.
9.
Wu
,
J. M.
, and
Tao
,
W. Q.
,
2008
, “
Numerical Study on Laminar Convection Heat Transfer in a Channel With Longitudinal Vortex Generator—Part B: Parametric Study of Major Influence Factors
,”
Int. J. Heat Mass Transfer
,
51
(
13–14
), pp.
3683
3692
.
10.
Ke
,
F.
,
Wang
,
L. B.
,
Hua
,
L.
,
Gao
,
S. D.
, and
Su
,
Y. X.
,
2006
, “
The Optimum Angle of Attack of Delta Winglet Vortex Generators on Heat Transfer Performance of Finned Flat Tube Bank With Considering Nonuniform Fin Temperature
,”
Exp. Heat Transfer
,
19
(3), pp.
224
238
.
11.
Gao
,
S. D.
,
Wang
,
L. B.
,
Zhang
,
Y. H.
, and
Ke
,
F.
,
2003
, “
The Optimum Height of Winglet Vortex Generators Mounted on Three-Row Flat Tube Bank Fin
,”
ASME J. Heat Transfer
,
125
(
6
), pp.
1007
1016
.
12.
Didarul
,
I. M.
,
Kenyu
,
O.
,
Minoru
,
Y.
, and Izuru, S.,
2007
, “
Study on Heat Transfer and Fluid Flow Characteristics With Short Rectangular Plate Fin of Different Pattern
,”
Exp. Therm. Fluid Sci.
,
31
(
4
), pp.
367
379
.
13.
Wang
,
L. B.
,
Yang
,
L. F.
,
Lin
,
Z. M.
,
Dong
,
Y. X.
,
Liu
,
S.
, and
Zhang
,
Y. H.
,
2009
, “
Comparisons of Performances of a Flat Tube Bank Fin Model Mounted Vortex Generators and the Real Heat Exchanger
,”
Exp. Heat Transfer
,
22
(
3
), pp.
198
215
.
14.
Song, K. W., and Wang, L. B., 2013, “
The Effectiveness of Secondary Flow Produced by Vortex Generators Mounted on Both Surfaces of the Fin to Enhance Heat Transfer in a Flat Tube Bank Fin Heat Exchanger
,”
ASME J. Heat Transfer
,
153
(4), p. 041902.
15.
Wang
,
L. B.
,
Li
,
X. X.
,
Lin
,
Z. M.
,
Yang
,
X.
, and
Wang
,
X. H.
,
2009
, “
Additional Description of Laminar Heat Convection in Tube With Uniform Wall Temperature
,”
J. Thermophys. Heat Transfer
,
23
(
1
), pp.
200
205
.
16.
Wang
,
L. B.
,
Zhang
,
Q.
, and
Li
,
X. X.
,
2009
, “
The Role of Velocity Gradient in Laminar Convective Heat Transfer Through a Tube With Uniform Wall Heat Flux
,”
Eur. J. Phys.
,
30
(
4
), pp.
823
833
.
17.
Wang
,
L. B.
,
Lin
,
Z. M.
,
Wu
,
X.
, and
Song
,
K. W.
,
2010
, “
Differences Between Laminar Convections Through Parallel Plain Planes With Uniform Wall Temperature and Heat Flux in Terms of Process Parameter
,”
Sci. China: Technol. Sci.
,
53
(3), pp. 789–799.
18.
Wang
,
L. B.
,
Lin
,
Z.
,
Hong
,
M.
,
Song
,
K. W.
, and
Wu
,
X.
,
2010
, “
Numerical Studying the Characteristics of Convective Transport of Heat Fluxes in Laminar Flow Through a Square Duct With Uniform Wall Temperature
,”
Comput. Therm. Sci.
,
2
(
5
), pp.
439
454
.
19.
Wang
,
L. B.
,
Huang
,
K.
,
Zhang
,
Y. H.
,
Yang
,
X.
, and
Wu
,
X.
,
2010
, “
A Way to Explain the Thermal Boundary Effects on Laminar Convection Through a Square Duct
,”
Front. Energy Power Eng. China
,
4
(
4
), pp.
496
506
.
20.
Wang
,
Y.
, and
Wang
,
L. B.
,
2012
, “
The Reason That Fluid Flow Dissipates the Same Energy But Obtains Different Convective Heat Transfer Intensity
,”
J. Enhanced Heat Transfer
,
19
(
1
), pp.
25
41
.
21.
Patankar
,
S. V.
,
1980
,
Numerical Heat Transfer and Fluid Flow
,
Hemisphere Publishing
,
New York
, pp.
330
351
.
22.
Lin
,
Z. M.
, and
Wang
,
L. B.
,
2014
, “
A Multi-Domain Coupled Numerical Method for a Flat Tube Bank Fin Heat Exchanger With Delta-Winglet Vortex Generators
,”
Numer. Heat Transfer Appl.
,
65
(
12
), pp.
1204
1229
.
You do not currently have access to this content.