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

Abstract

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.