Numerical study of turbulent forced convection in coiled flow inverter

Abstract

A numerical study is done to investigate turbulent forced convection in a new device of coiled flow inverter. The proposed device works on the technique based on flow inversion by changing the direction of centrifugal force in helically coiled tubes thus enabling rotation of the plane of vortex. The objective of the present study is to characterize the flow development and temperature fields in coiled flow inverter (CFI) under turbulent flow for the range of 10,000 < N Re < 30,000. The flow pattern obtained for the curved tubes are in agreement to those observed by the previous investigators [1,2]. However, a slight rotation of contours was observed in case of helical coil with finite pitch. Similar rotation of contours was found even with fluids of different Prandtl number (0.7 ≤ N Pr ≤ 150) in helical coil with constant pitch. The study was also carried out for different fluids (air, water, kerosene and ethylene glycol). The coiled flow inverter shows 4–13% enhancement in the heat transfer as compared to the straight helical coil while relative pressure drop is 2–9%. The gain in heat transfer in coiled flow inverter for turbulent flow condition as compared to the straight tube for same flow rate and boundary conditions is 35–45% while the increase in pressure drop is 29–30%.