ENHANCEMENT OF HEAT TRANSFER IN TURBULENT FLOW THROUGH A TUBE WITH A PERFORATED TWISTED TAPE INSERT

An experimental investigation has been carried out for turbulent flow in a circular tube with a porous/perforated twisted tape insert. Heat transfer and pressure drop characteristics are examined in tubes with perforated twisted tape inserts for turbulent flow. The air velocity, temperature, tube wall temperature, and pressure drop are measured both for smooth/plain tubes and tubes with perforated twisted tape inserts for a wide range of Reynolds numbers (1.3 x 10(4) to 5.2 x 10(4)). The heat transfer coefficients, Nusselt numbers, pumping power, and heat transfer effectiveness are calculated for smooth/plain tubes as well as for tubes with perforated twisted tape inserts. The heat transfer coefficient is enhanced (up to 5.5 times) in the cost of increasing pumping power (1.8 times) in turbulent flow through a tube with the inserts. The heat transfer effectiveness in a tube with a perforated twisted tape insert is found to increase up to 4.0 times compared with the value for the plain tube.