Thermohydraulic Study of Laminar Swirl Flow Through a Circular Tube Fitted With Twisted Tapes

Heat transfer and pressure drop characteristics in a circular tube fitted with twisted tapes have been investigated experimentally. Laminar swirl flow of a large Prandtl number (205<Pr<518) viscous fluid was considered. The swirl was generated by short-length twisted-tape inserts; regularly spaced twisted-tape elements with multiple twists in the tape module and connected by thin circular rods; and smoothly varying (gradually decreasing) pitch twisted-tapes. The heat transfer test section was heated electrically imposing axially and circumferentially constant wall heat flux (UHF) boundary condition Reynolds number, Prandtl number, twist ratio, space ratio, number of tuns in the tape module, length of the twisted-tape and smoothness of the swirling pitch govern the characteristics. Friction factor and Nusselt number are lower for short-length twisted-tape than those for full-length twisted-tape

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