Heat Transfer and Friction Factor Characteristics in Twisted Square Ducts

The present work experimental and numerical investigations have been carried out to study friction factor and heat transfer characteristics of twisted square ducts. Experiments were conducted for different velocities of air under constant heat flux condition, twist ratio is equal to 6.12 and also Reynolds number varied from 8000 to 30000. The experimental analysis has been carried out and the experimentation is completely based upon design of experiments to get the optimum heat transfer rate and minimize pressure drop. The results of friction factor, Nusselt number and thermal performance factor are presented. Twisted square duct shows relatively higher heat transfer and optimum pressure drop compared to plain square duct. The experimental results shows that Nusselt number for the twisted square duct is about 1.89 times above that for the plain square duct while friction factor is 2.29 times higher (f/fo= 2.29). Thermal performance (enhancement ratio) of the twisted square duct is 1.41. In this work Numeric simulations were calculated by using the CFD software package ANSYS 18.2 FLUENT has been used. Heat transfer and numerical flow behaviors such as temperature, friction factor contours of the are also reported. Hence it is concluded that square duct with twist ratio 6.12 gives highest heat transfer and thermal performance due to lowest friction loss indicating promising device of the twisted square duct.