Investigations on the effect of disturbed flow using differently configured turbulators and Alumina nanofluid as a coolant in a double tube heat exchanger

摘要

This paper investigates the effect of the combined passive technique on heat transfer enhancement, friction factor, and thermal performance of a double-tube heat exchanger fitted with differently configured turbulators and using Alumina nanofluid. The performance parameters are studied for fixed flow rate (Re = 2500) of water at constant heat flux in the inner tube (hot fluid) and varying flow rates (500 <= Re <= 5000) of Alumina nanofluid (volume concentrations: 0.05-0.15%) flowing in the outer tube (cold fluid). The configurations tested are a peripherally V-cut twisted tape (Twist Ratio = 20, 13.3, and 9.8) and a propeller turbulator (Number of propellers: 6, 8, and 10). The results show increased Nusselt number by 22.4% and 29.43%, increased Thermal Performance Factor by 1.25 and 1.33, respectively, for decreased twist ratio and increased number of propellers and volume concentration of Alumina nanofluid. The peripherally V-cut twisted tape (TR = 9.8) and propeller turbulator (Number of propellers = 10) with 0.15% volume concentrations of Alumina nanofluid combination give better performance, with a slight penalty in pressure drop. The correlations for the Nusselt number and friction factor are developed from the experimental data, which are fairly in good agreement with the experimental data.