Experimental investigation of heat transfer and pressure drop of turbulent flow inside tube with inserted helical coils

The heat transfer and pressure drop were experimentally investigated in a coiled wire inserted tube in turbulent flow regime in the range of Reynolds number of 14,400 Re 42,900. The present work aims to extend the experimental data available on wire coil inserts to cover wire diameter ratio of 0.044 e/d 0.133 and coil pitch ratio of 1 p/d 5. Uniform heat flux was applied to the external surface of the tube and air was selected as fluid. The effects of Reynolds number and wire diameter and coil pitch ratios on the Nusselt number and friction factor were studied. The enhancement efficiency and performance criteria ranges are of (46.9-82.6 %) and (100.1-128 %) within the investigated range of the different parameters, respectively. Correlations are obtained for the average Nusselt number and friction factor utilizing the present measurements within the investigated range of geometrical parameters and Re. The maximum deviation between correlated and experimental values for Nusselt number and friction factor are +/- 5 and +/- 6 %, respectively.