In this paper, three-dimensional numerical simulations with renormalization-group (RNG) k-ε model are performed for the air-side heat transfer and fluid flow characteristics of wavy fin-and-tube heat exchanger with delta winglet vortex generators. The Reynolds number based on the tube outside diameter varies from 500 to 5000. The effects of different geometrical parameters with varying attack angle of delta winglet (β=30deg, β=45deg, and β=60deg), tube row number (2–4), and wavy angle of the fin (θ=020deg) are examined. The numerical results show that each delta winglet generates a downstream main vortex and a corner vortex. The longitudinal vortices are disrupted by the downstream wavy trough and only propagate a short distance along the main flow direction but the vortices greatly enhance the heat transfer in the wake region behind the tube. Nusselt number and friction factor both increase with the increase in the attack angle β, and the case of β=30deg has the maximum value of j/f. The effects of the tube row number on Nusselt number and friction factor are very small, and the heat transfer and fluid flow become fully developed very quickly. The case of θ=5deg has the minimum value of Nusselt number, while friction factor always increases with the increase in wavy angle. The application of delta winglet enhances the heat transfer performance of the wavy fin-and-tube heat exchanger with modest pressure drop penalty.

1.
Wang
,
C. C.
,
Lo
,
J.
,
Lin
,
Y. T.
, and
Wei
,
C. S.
, 2002, “
Flow Visualization of Annular and Delta Winglet Vortex Generators in Fin-and-Tube Heat Exchanger Application
,”
Int. J. Heat Mass Transfer
0017-9310,
45
, pp.
3803
3815
.
2.
Tiwari
,
S.
,
Maurya
,
D.
,
Biswas
,
G.
, and
Eswaran
,
V.
, 2003, “
Heat Transfer Enhancement in Cross-Flow Heat Exchangers Using Oval Tubes and Multiple Delta Winglets
,”
Int. J. Heat Mass Transfer
0017-9310,
46
, pp.
2841
2856
.
3.
O’Brien
,
J. E.
,
Sohal
,
M. S.
, and
Wallstedt
,
P. C.
, 2004, “
Local Heat Transfer and Pressure Drop for Finned-Tube Heat Exchangers Using Oval Tubes and Vortex Generators
,”
ASME J. Heat Transfer
0022-1481,
126
, pp.
826
835
.
4.
Biswas
,
G.
,
Mitra
,
N. K.
, and
Fiebig
,
M.
, 1994, “
Heat Transfer Enhancement in Fin-Tube Heat Exchangers by Winglet Type Vortex Generators
,”
Int. J. Heat Mass Transfer
0017-9310,
37
, pp.
283
291
.
5.
Leu
,
J. S.
,
Wu
,
Y. H.
, and
Jang
,
J. Y.
, 2004, “
Heat Transfer and Fluid Flow Analysis in Plate-Fin and Tube Heat Exchangers With a Pair of Block Shape Vortex Generators
,”
Int. J. Heat Mass Transfer
0017-9310,
47
, pp.
4327
4338
.
6.
Torii
,
K.
,
Kwak
,
K. M.
, and
Nishino
,
K.
, 2002, “
Heat Transfer Enhancement Accompanying Pressure-Loss Reduction With Winglet-Type Vortex Generators for Fin-Tube Heat Exchangers
,”
Int. J. Heat Mass Transfer
0017-9310,
45
, pp.
3795
3801
.
7.
Jain
,
A.
,
Biswas
,
G.
, and
Maurya
,
D.
, 2003, “
Winglet-Type Vortex Generators With Common-Flow-Up Configuration for Fin-Tube Heat Exchangers
,”
Numer. Heat Transfer, Part A
1040-7782,
43
, pp.
201
219
.
8.
Joardar
,
A.
, and
Jacobi
,
A. M.
, 2008, “
Heat Transfer Enhancement by Winglet-Type Vortex Generator Arrays in Compact Plain-Fin-and-Tube Heat Exchangers
,”
Int. J. Refrig.
0140-7007,
31
, pp.
87
97
.
9.
Wang
,
L. B.
,
Ke
,
F.
,
Gao
,
S. D.
, and
Mei
,
Y. G.
, 2002, “
Local and Average Characteristics of Heat/Mass Transfer Over Flat Tube Bank Fin With Four Vortex Generators per Tube
,”
ASME J. Heat Transfer
0022-1481,
124
, pp.
546
552
.
10.
Smotrys
,
M. L.
,
Ge
,
H.
,
Jacobi
,
A. M.
, and
Dutton
,
J. C.
, 2003, “
Flow and Heat Transfer Behavior for a Vortex-Enhanced Interrupted Fin
,”
ASME J. Heat Transfer
0022-1481,
125
, pp.
788
794
.
11.
Joardar
,
A.
, and
Jacobi
,
A. M.
, 2005, “
Impact of Leading Edge Delta-Wing Vortex Generators on the Thermal Performance of a Flat Tube, Louvered-Fin Compact Heat Exchanger
,”
Int. J. Heat Mass Transfer
0017-9310,
48
, pp.
1480
1493
.
12.
Sanders
,
P. A.
, and
Thole
,
K. A.
, 2006, “
Effects of Winglets to Augment Tube Wall Heat Transfer in Louvered Fin Heat Exchangers
,”
Int. J. Heat Mass Transfer
0017-9310,
49
, pp.
4058
4069
.
13.
Tao
,
W. Q.
, 2001,
Numerical Heat Transfer
,
2nd ed.
,
Xi’an Jiaotong University
,
Xi’an, China
, in Chinese.
14.
Tian
,
L. T.
,
He
,
Y. L.
,
Tao
,
Y. B.
, and
Tao
,
W. Q.
, 2009, “
A Comparative Study on the Air-Side Performance of Wavy Fin-and-Tube Heat Exchanger With Punched Delta Winglets in Staggered and In-Line Arrangements
,”
Int. J. Therm. Sci.
1290-0729, in press.
15.
Schmidt
,
T. E.
, 1949, “
Heat Transfer Calculations for Extended Surfaces
,”
Refrig. Eng.
0096-0470,
4
, pp.
351
357
.
16.
Xue
,
W.
, and
Min
,
J. C.
, 2004, “
Numerical Predictions of Fluid Flow and Heat Transfer in Corrugated Channels
,”
Proceedings of the Third International Symposium on Heat Transfer and Energy Conservation
, Guangzhou, China, Jan. 12–15, Vol.
1
, pp.
714
721
.
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