NUMERICAL ANALYSIS OF HEAT TRANSFER ENHANCEMENT IN CONICAL-NOZZLE TURBULATORS INSERTED TUBE

This numerical work is associated with the investigation of the effect of turbulator arrangement (diverging and converging) on heat transfer enhancement in conical nozzle turbulators inserted circular tube. Three different pitch ratios (PR=2.5, 5 and 7.5) were considered in the numerical analyses, using air as test fluid. The numerical results of Nusselt number, friction factor and thermal performance factor were introduced for the range of Reynolds numbers of 6000-24000. The obtained results showed that smaller pitch ratios provided more heat transfer rate and pressure drop. As compared to converging nozzles, diverging nozzles generated more effective turbulance/reverse flow, and thus provided higher heat transfer and flow friction. Evidently, obtained results revealed that the usage of nozzle-turbulators as a turbulence/reverse flow generator has an important contribution on heat transfer improvement.