A numerical study of heat transfer in fin?tube heat exchangers using winglet-type vortex generators in common-flow down configuration

2003 ◽  
Vol 3 (1) ◽  
pp. 32 ◽  
Author(s):  
S. Tiwari ◽  
P. L. N. Prasad ◽  
G. Biswas
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Vortex Generators ◽  
Fin Tube

Numerical Prediction of Enhanced Heat Transfer Using Oval Tubes and Delta Winglets

2002 ◽  
Author(s):  
D. Maurya ◽  
S. Tiwari ◽  
G. Biswas ◽  
V. Eswaran ◽  
A. K. Saha
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Power Plants ◽  
Transport Coefficients ◽  
Three Dimensional ◽  
Cross Flow ◽  
Vortex Generators ◽  
Delta Winglet ◽  
Fin Tube ◽  
Oval Tube

Unsteady three-dimensional laminar flow and heat transfer in a channel with a built-in oval tube and delta winglets have been obtained through the solution of the complete Navier-Stokes and energy equations using a body-fitted grid and a finite-volume method. The geometrical configuration represents an element of a gas-liquid fin-tube cross flow heat exchanger. The air-cooled condensers of the geothermal power plants also use fin-tube heat exchangers. The size of such heat exchangers can be reduced through enhancement in transport coefficients on the air (gas) side, which are usually small compared to the liquid side. In a suggested strategy, oval tubes are used in place of circular tubes, and delta winglet type vortex generators in common-flow-down configuration are mounted on the fin-surface in front of the tubes, while another delta winglet pair in common-flow-up configuration is mounted downstream of the first set of winglets. An evaluation of this augmentation strategy is attempted in this investigation. The investigation was carried out for a winglet angle of attack of 40 degrees to the incoming flow. The structures of the velocity field, and the heat transfer characteristics have been presented. The results indicate that vortex generators in conjunction with the oval tube show definite promise for the improvement of fin-tube heat exchangers.

A Numerical Study of Air-Side Heat Transfer Enhancement Using V-Formation Delta-Winglet Vortex Generators in Heat Exchangers

2011 ◽  
Author(s):  
Junling Xie ◽  
Liping Liu
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Attack Angle ◽  
Vortex Generators ◽  
Single Pair ◽  
Transfer Enhancement ◽  
Large Pair ◽  
Delta Winglet

The numerical study proposed is to investigate the effectiveness of delta-winglet vortex generators (VGs) used for heat-transfer enhancement in a horizontal rectangular channel as a typical air passage for fin-and-tube heat exchangers. The effects of four different configurations of vortex generators have been investigated: (1) single pair VGs with a 30 degree attack angle; (2) 2-pair VG array with a 30 degree attack angle; (3) single pair VGs with a 45 attack angle; (4) 2-pair VG array with a 45 attack angle. The numerical results indicate that average Nusselt number increase is 31%–38% and 51%–71% for the channel mounted with VGs with a 30 degree attack angle and a 45 degree attack angle, respectively. The enhancement for single large pair of VGs is higher than that for a V-formation array with 2 small pairs. However, VGs also introduce extra pressure drop penalties to the channel flow, and higher heat-transfer performance is also accompanied by a larger pressure drop penalty. According to the results, a single large pair of VGs with 45 attack angle shows the best overall performance among all the configurations investigated.

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