ENHANCEMENT OF HEAT TRANSFER OF WATER FOR TURBULENT FLOW THROUGH TUBE USING U-CUT TWISTED TAPE INSERTS

Abstract

In this experiment tube side heat transfer coefficient, pressure drop, friction co-efficient and percentage of increase in those parameters for water using U-cut twisted tape inserts into the tube were measured. The test section consists of a circular tube made of copper having 26.6 mm inside diameter, 30 mm outside diameter and 900 mm in effective length. A stainless steel U-cut twisted tape insert of 5.29 twist ratio and 0.4 mm in thickness was inserted into the smooth tube. The U-cut had 8 mm depth and 8mm width. In this investigation, the test section was electrically heated. Five K-type thermocouples were used in the test section for measuring the wall temperature. The heat flux was found in the range of 18.33~28 kW/m2 for smooth tube whereas 32.07~47.24.00 kW/m2 for tube with insert for Reynolds number range of 10153~19217. At comparable Reynolds number, Nusselt number in the tube with U-cut twisted tape insert was enhanced by 2.76 to 3.24 times with compared to smooth tube and friction factor in the tube with U-cut twisted tape insert was also increased by 1.6 times with compared to plain tube.