Local & Average Heat Transfer and Friction Factor Characteristics of a Flow through a Helical Wire Coil for Turbulent Flow Conditions

Abstract

Heat transfer augmentation is essential for numerous industrial applications. The flow through a helical coil is one of the most efficient and effective techniques of heat transfer enhancement due to the provision of a large surface area. The present study is focused on the thermo-hydraulic performance of turbulent flow through a helical coil, made up of copper with a curvature ratio of 0.0519 (d/D) and pitch equal to 50 mm using water as a test fluid. The objective of the present study is to reveal the influence of secondary flow, centrifugal force, and Reynolds number (Re) on local velocity, local heat transfer coefficient in a helical coil. The values of average heat transfer and friction factor at different Re for a flow through a helical coil are compared with corresponding values for a flow through a smooth tube. The numerical results are presented for the Re number range at inlet conditions of the helical coil from 5000 to 20000 in the increment of 2500 under constant heat flux conditions. Numerical results indicate that there is a circumferential variation of local velocity and local Nusselt number (Nu) values concerningthe inner and outer sides of the helical coil. The values of average heat transfer are observed to be 150 to 200% more than the smooth tube values with increased pressure drop.