Determination of Thermal Performance of Perforated Variable Pitch Twisted Tape Inserts

Abstract

In the past few years, a number of trials and studies are being done to improve heat transfer techniques to reduce the thermal resistance, by increasing the effective heat transfer surface area or by generating turbulence into the heat exchangers. The effectiveness of a heat transfer enhancement technique is determined by the Thermal Performance Factor which is a ratio of the change in the heat transfer rate to change in friction factor. To achieve this, in a tube in tube heat exchangers, a variety of tube inserts such as swirl flow generator, wire coil, twisted tape, etc. are used. In this research work, different types of twisted tape tube insert with different geometries like twisted tape with perforations; winglets, variable twist pitch of twisted tapes, etc. are studied in order to understand the current mechanism of fluid flow and heat transfer. Suitably, an attempt has been made to explore the new geometry of twisted tape having perforations with variable pitch. This new geometry will be studied to clarify the fluid flow behavior that controls the heat transfer rates across the thermal boundary layer attached to the tube wall.