A Study of Heat Transfer Characteristics of Double Pipe Heat Exchanger with Twisted Tape Inserts

Abstract

This research studied the heat transfer characteristics in a double pipe heat exchanger fitted with full length twisted tape and the twisted ? tapes were made from steel and aluminum. The test sections were built from steel and copper tubes ID 54.5 mm and 25.5 mm, thickness 1.5 mm and length 2 m. In the experiments, the hot water was flowed through the inner tube fitted with a twisted ? tape while the cold water was passed in the counter flow through the annulus. The volume flow rate of hot and cold water were flowed at 4, 6, 8 and 10 LPM while the inlet temperature of cold water was constant at 30^o C and hot water was 50, 55 and 60^o C, respectively. The pitch of a twisted ? tape was 160 mm and thickness 2 mm. The experimental data of the tube fitted with a twisted ? tape was compared with the plain tube data obtained. From the experimental results, a twisted ? tape gave better heat transfer rate than the plain tube. It can be noted that the swirl flow helped to increase of the overall heat transfer coefficient (U). The test results found that the average value of U for Aluminum, Steel and plain tubes were 876, 738 and 660 W/m².^oC, respectively.