Author : Shyam S. Darewar, Vinayak M. Kale

The present experimentation is on rotary twisted tape insert with a three different twist ratio y= 3.0, 4.0 and 5.0. The Reynolds number used is in the range of 35000 to 45000. The effect of rotary twisted tape on heat transfer enhancement and pressure drop has been studied. The twisted tape inserts develops a strong swirl flow within fluid flow which increases heat transfer rate. A constant heat flux condition was used for experimentation. The experimental results shows that the maximum heat transfer coefficient of fixed twisted tape insert is 1.55 times the pipe without insert at y=3.0 and Reynolds number 45000 and when we compare these results with rotary twisted tape inserts the maximum heat transfer coefficient obtained is 1.98 times the smooth pipe for y=3.0 and at the speed of 150RPM. The pressure drop occurred is 4.14 times at y=3.0, 3.85 at y=4.0 and 3.42 at y=5.0 with respect to plain tube but these values does not changes significantly with the rotary twisted tape inserts at various RPM.

Keywords: Heat transfer coefficient, Rotary twisted tape inserts, Nusselt number Ratio, pressure drop, swirl flow.