RANS analysis of turbulent flow and heat transfer in a helically-coiled tube

In this study, turbulent flow and heat transfer characteristics in a helically-coiled tube have been numerically investigated. They have been widely studied experimentally; however, most studies have focused on the pressure drop and heat transfer correlations. The centrifugal force caused by a helical tube increases the wall shear stress and heat transfer rate at the outer side of the tube, while decreasing those at the inner side of tube. This study shows the variation of the local Nusselt number and friction factor along the circumference at the wall of a helical tube. It is seen that the local heat transfer rate and wall shear stress greatly decrease near the inner side of the tube, which can affect the safety of the tube materials. CFD simulations are carried out by varying the coil diameter and Reynolds number, and their influence on turbulent flow and heat transfer has also been studied.