Synergistic effects of twisted tape geometry and nanoparticles on heat transfer performance in tubes

Increasing heat transfer in pipes has been an important issue for efficiency in recent years. For this reason, many passive methods have been used and have found a place in research. Twisted tape insert additional parts are one of these passive methods and stand out as structures that increase heat transfer by changing the flow regime and movement in the pipe. These parts act as turbulators by creating vortex motion in certain regions within the flow and improve the heat transfer coefficient by disrupting the thermal boundary layer. This study examines the effects of the twisted tape geometry used in pipes on heat transfer enhancement with nanoparticles. The main purpose is to examine and observe the increase in heat transfer enhancement by adding nanoparticles with various nanoparticle concentrations into the liquid to be used and the twisted tape insert added to the model structure with different twist ratios. Using Computational Fluid Dynamics (CFD) simulations, the heat transfer behavior of the nanofluid in the pipe with twisted tape geometry is simulated. The results obtained from these simulations show that increasing the nanoparticle concentration maximizes the heat transfer performance, and the most efficient twisted tape insert design is depicted to be the one with twist ratio of 4. It has been observed that the use of Al2O3-TiO2 (10-6%) nanofluid has a highly positive effect on the system. Comparisons are made regarding Nusselt number, friction factor and Performance evaluation criteria (PEC).