Numerical simulation of heat transfer characteristics in conical spiral tubes with uniform wall temperature

Abstract

Curved tube are widely used in heat exchangers for its higher heat transfer rate due to the presence of secondary flow compared to that in straight tubes. However, very limited studies related to heat transfer characteristic of curved tube with varying curvature i.e. conical spiral tube, along with the length have been undertaken. The present study investigates the influence of Reynolds number for the range of 104 to 105 and geometrical parameters like cone taper angle (10° - 60°), coil pitch (0,03 m and 0.055m) and coil curvature (maximum radius, 0.15 m and 0.2 m) on local circumferential and coil heat transfer. It is found that local circumferential and coil heat transfer increases with the increase in cone taper angle, curvature ratio (d/D), pitch and Reynolds number. Increase in cone taper angle, coil pitch and curvature ratio (d/D) increases local heat transfer variation at inner circumference while it becomes more uniform at outer circumference. A correlation to predict Nusselt number for turbulent flow in conical spiral tube for various cone taper angle and curvature ratio is proposed on the basis of numerical analysis.