Experimental Analysis of Heat Transfer Improvement of Water Utilizing Double Counter Twisted Tape Insert

Abstract

This investigation was done for improving tube side heat transfer execution by double counter twisted tape insert. The test segment comprises of a long copper tube of 26.6 mm inlet diameter and 30 mm external diameter and length was 900 mm. The inserts were 850 mm in long, 8.5 mm in width, 1.5 mm in thickness and twist ratio was 6.25. Two thermometers were utilized at the inlet and outlet segment of the circular tube for estimating the bulk temperature. Five K type thermocouples were utilized in the test area to estimate the outer surface temperature. From rotameter, a certain amount of mass flow rate was estimated for calculation of water flow velocity. Just as from manometer reading, pressure head was estimated for measuring the pressure difference of the flow segment. After measuring all the parameter values, Reynolds Number, heat transfer rate, convective heat transfer coefficient, Nusselt Number, Prandtl Number, experimental friction factor was calculated. At comparable Reynold number 2960 to 5382 Nusselt Number was increased by 60.5% to 70.8% for double counter twisted tape insert compared to plain tube. At comparable Reynold number 2960 to 5382 friction factor of the insert was also increased 1.05 to 1.37 times compared to plain tube. From previous data of segmented twisted tape there showed a comparison of Nusselt number of Double counter twisted tape (31.6 to 42.6) which is higher than the segmented twisted tape (20 to 37) at same Reynold number 2960 to 5382.