Heat Transfer Enhancement of Laminar Flow in a Circular Tube Using Swirl/Vortex Generator

Swirl/vortex flow generator is an important form of passive augmentation techniques consist of a variety of tube inserts, geometrically varied flow arrangements and duct geometry modifications that produce flows. Twisted-tape is one of the most important members of this form which used extensively in different type heat exchangers. This paper presents a research on heat transfer enhancement and friction factor characteristics in a circular tube using CFD simulation. Plain twisted tape inserts with twist ratios (y = 2.93, 3.91) and slant baffled twisted tape inserts with baffle angle 30° and twist ratio (y = 2.93) have been used for the simulation. The results obtained by simulation matched with the literature correlations for plain tube with the discrepancy of less than ±8% for Nusselt number and ±6.25% for friction factor. The results have also revealed that the heat transfer in term of the Nusselt number enhanced with increases of Reynolds number, decreases of twist ratio. Among the various twist ratios, the slant baffled twisted tape with twist ratio of y = 2.93 has offered a maximum heat transfer enhancement with signifi cant friction factor.