NUMERICAL PREDICTION OF HEAT TRANSFER IN A CHANNEL WITH A BUILT-IN OVAL TUBE AND TWO DIFFERENT SHAPED VORTEX GENERATORS

Existing air-cooled condensers in geothermal power plants use fin-tube heat exchangers with circular tubes. The size of the air-cooled condensers is huge, and often the cost of the condensers is about one third of the plant cost. An effort is being made to reduce the size of the air-cooled condensers by enhancing the transport coefficients on the heat exchange surfaces. Improvement over the common fin-tube heat exchangers can be brought about by a strategic modification. First, the oval tubes may replace the circular tubes. Second, the delta-winglet type vortex generators can be added on the flat surfaces to improve the heat transfer even further. Finally, a rectangular winglet pair can be deployed instead of a delta winglet pair and the performance of two different shaped vortex generators can be compared. A computational study has been undertaken to show the promise of above-mentioned combinations on a representative element of a heat exchanger.

[1]  Tong-Miin Liou,et al.  Heat Transfer and Fluid Flow in a Square Duct With 12 Different Shaped Vortex Generators , 2000 .

[2]  W. Kordulla,et al.  Efficient computation of volume in flow predictions , 1983 .

[3]  M. Fiebig,et al.  Conjugate heat transfer of a finned oval tube with a punched longitudinal vortex generator in form of a delta winglet—parametric investigations of the winglet , 1998 .

[4]  Richard J Goldstein,et al.  The effect of a wall boundary layer on local mass transfer from a cylinder in crossflow , 1984 .

[5]  I. Orlanski.  A Simple Boundary Condition for Unbounded Hyperbolic Flows , 1976 .

[6]  C. Rhie,et al.  Numerical Study of the Turbulent Flow Past an Airfoil with Trailing Edge Separation , 1983 .

[7]  T. Liou,et al.  Heat Transfer and Fluid Flow in a Square Duct With 12 Different Shaped Vortex Generators , 1999 .

[8]  Heat transfer in a conjugate heat exchanger with a wavy fin surface , 1999 .

[9]  S. Majumdar.  Role of underrelaxation in momentum interpolation for calculation of flow with nonstaggered grids , 1988 .

[10]  F. Harlow,et al.  Numerical Calculation of Time‐Dependent Viscous Incompressible Flow of Fluid with Free Surface , 1965 .

[11]  Gautam Biswas,et al.  Heat transfer enhancement in fin-tube heat exchangers by winglet type vortex generators , 1994 .

[12]  Koichi Nishino,et al.  Numerical and experimental determination of flow structure and heat transfer effects of longitudinal vortices in a channel flow , 1996 .

[13]  James E. O'Brien,et al.  Local Heat Transfer for Finned-Tube Heat Exchangers using Oval Tubes , 2000 .

[14]  M. Sen,et al.  Enhancement of heat transfer in an inviscid-flow thermal boundary layer due to a Rankine vortex , 1998 .