Development of new correlations for heat transfer and friction loss of solid ring with combined square wing twisted tape inserts heat exchanger tube

An experimental analysis has been carried out for heat transfer and turbulent flow in a heat exchanger circular tube with solid ring with combined square wing twisted tape (TT) inserts. Experimentations are performed varying the solid ring with combined square wing TT insert parameters, such as changing the number of TT inserts from 1.0 to 4.0, ring pitch ratio from 0.5 to 2.0, wing pitch ratio from 2.0 to 3.5, wing depth ratio from 0.083 to 0.333, ring diameter ratio from 0.831 to 0.932, and Reynolds number in the range of 3,000-21,000. The experimental results show that the heat transfer is increased around 5.66 times more than the plane circular tube. The thermal hydrodynamic performance is evaluated for the optimum range of solid ring with combined square wing TT insert parameters. Statistical correlations are developed and a deviation of correlation data from the experimental data of Nusselt number and friction factor is about +/- 9% and +/- 6%, respectively. The correlation is helpful in prediction of the thermal performance for turbulent flow through a circular tube with solid ring with combined square wing twisted tape inserts.