Effect of Curvature Ratio on The Heat Transfer and Pressure Drop in Coiled Tube

Abstract

An experimental study has been conducted on steady-state natural convection heat transfer from helical coil tubes. Water was used as a bath liquid without any mixing and air was used as a coolant fluid. A straight copper tube of 13 mm ID, 14 mm OD and 3 m length was bend to fabricate the helical coil. Two coils are used in this experiment has a curvature ratio of 0.1101 and 0.0942. The data were correlated using tube diameter as the characteristic length. The results show that the overall heat transfer coefficient and pressure drop are increased when the flow rate of coolant and curvature ratio increase. Two correlations are presented to calculate the average Nusselt number inside and outside of coil