Heat Transfer Augmentation in a Circular tube and Square duct Fitted with Swirl Flow Generators: A Review

The present paper is a review of research work in last decade on heat transfer enhancement in a circular tube and square duct. In the present paper emphasis is given to works dealing with twisted tape ,screw tape inserts because according to the recent studies, these are known to be economic tool in the field of heat transfer enhancement. Passive techniques, where inserts are used in the flow passage to increase the heat transfer rate, are advantageous compared with active techniques, because the insert manufacturing process is simple and cheap and these techniques can be easily employed in an existing heat exchanger. The thermohydraulic performance of above inserts depends on the various factors such as flow conditions, geometry of pipe and insert configurations. The present review is organized separately according to type of insets, pipe geometry, for laminar and turbulent flow respectively.