Review on Extended Surfaces used in Concentric Tube Heat Exchanger

Improving heat transfer in double heat exchanger has led to large number of studies. Double heat exchanger is commonly used in industries due to its simplicity; flexibility had a wide range of applications. One of the methods used in passive technique is use of extended surfaces. This review paper presents increasing heat transfer rate by using fins in double pipe heat exchanger over the previous years but majorly in the last decade in the process of heat transfer. Common methods used for heat transfer improvement are active, passive and compound methods in double pipe heat exchanger.