HEAT TRANSFER AUGMENTATION OF LAMINAR NANOFLUID FLOW IN HORIZONTAL TUBE INSERTED WITH TWISTED TAPES

In this paper, an experimental study on the heat transfer enhancement and friction factor characteristics for fully developed laminar CuO/distilled-water (DI-water) nanofluid flow through horizontal tube inserted with different geometries of twisted tapes under constant heat flux condition ranged from 4483 to 10000 W/m^2. φ=0.08% and 0.35% volume concentrations of CuO nanoparticles are suspending in distilled water to prepare nanofluid. Twisted types made from copper material with twist ratios Y=2.6 and 5.3 twist ratios, thickness t=1 and 2mm and with semicircular and triangular cuts shape were used to study their effect on twisted tape performance. Results showed that both convective heat transfer in terms of average Nusselt number (Nu) ? and friction factor have significantly increasing with inserting twisted tape with nanofluids as working fluid comparing with nanofluids or DI-water in smooth tube case and this enhancement increases as both Reynold number and volume concentration increases. Triangular cut twisted tape (TCTT) at Y=2.6 and t=2mm with CuO nanofluid at φ=0.35% showed the best preformance among the other twisted tapes on heat transfer enhancement where (Nu) ? increased by 73% than smooth tube with DI-water, while friction factor increased by 62%. New Empirical correlations have been developed for both average Nusselt number and friction factor in the terms of the parameters mentioned above.