HEAT TRANSFER ENHANCEMENT IN A TUBE FITTED WITH TWISTED TAPE SWIRL GENERATOR

摘要

Flow friction, heat transfer and thermal performance characteristics in a tube fitted with peripherally-cut twisted tape (PT) have been experimentally investigated. The twist ratio (y/W) of twisted tape was varied from 3 to 5 while the depth of peripheral cut ratio (d/W) and the width of peripheral cut ratio (w/W) were both kept constant at 0.22. The experiments were conducted for the Reynolds number ranging from 5100 to 19,700, using water as a working fluid. The plain tube and the tube equipped with the typical twisted tape (77) with three different twist ratios (y/W =3,4 and 5) were also tested for comparison. The obtained results reveal that the use of PT enhances Nusselt number up to 211% and 138% compared to those of the plain tube and the tube with TT, respectively. It is also found that heat transfer rate increases with decreasing twist ratio. Additionally, the performance evaluation to assess the real benefits in using the PT as heat transfer enhancer has also been determined.