Heat Transfer Augmentation Technique for Combined Coiled Insert and Dimple Tube: A Review

Heat transfer enhancement techniques are used to augment heat transfer rate. Heat transfer enhancement techniques are most commonly used in areas such as radiators for space vehicles, thermal power plants, automobiles, refrigeration and air-conditioning equipment�s ,coolant (oil) cooling systems, , heating and cooling in evaporators, process industries, industrial heat recovery equipment�s, power sectors, electronic cooling aerospace, etc. These techniques broadly classified into three categories viz. passive techniques, active techniques, a combination of passive and active techniques i.e. called compound techniques. Passive techniques, where inserts are incorporated in the flow passage to enhance rate of heat transfer, are very advantageous as well as effective as compared with active techniques, because the insert manufacturing process is simple and these techniques can be easily employed in an existing heat exchanger. In design of compact heat exchangers, passive techniques of heat transfer augmentation can play an important role if a proper passive insert configuration can be selected according to the heat exchanger working condition (both flow and heat transfer conditions). In the past decade, various types of studies have been reported on the passive techniques of heat transfer augmentation. The present paper is a review on progress with the passive augmentation techniques in the recent past and will be useful to designers implementing passive augmentation techniques in heat exchange. The heat either may be used to add or reject from the system. There are many types of heat losses observed in these processes researchers are working hard to minimize these losses and enhance the heat transfer rate in either directions. This paper made an attempt to review the some of the passive techniques and revel the possibilities of the combined approach of this technique.