Numerical Investigation of a Double Pipe Heat Exchanger Using a Twisted Tape Inside and Helical Tape Outside Pipe Surfaces

This research paper explores the enhancement of heat transfer and pressure drop performance in pipe-in-pipe heat exchangers through the strategic use of insertion for helical and twisted tape. The analysis reveals that tape inserts generate longitudinal vortices, enhancing fluid mixing and leading to higher heat transfer rates when related to plain tube counterparts. The friction factors, though greater with inserts, display an interesting relationship with heat transfer, and the effect of helical shapes on fluid path length is examined. The simulation utilizes the SIMPLE algorithm for solving continuity, momentum, energy equations, with the upwind method with second order for discretization and a pressure-based solver. Turbulence modeling uses the shear stress transfer model with heat flux set at zero. The outcomes reveal that the twist ratio significantly influences flow characteristics, with the effect on the friction factor being dependent on the Reynolds number. There is a corresponding increase in pressure drop with increasing Reynolds number. Notably, helical tape inserts with a greater twist ratio and twisted tape designs show improved convective heat transfer over plain pipes.