Heat transfer enhancement technology is the process of improving the performance of a heat transfer by increasing the convection heat transfer coefficient. Generally the main objective is to reduce the size and costs of heat exchangers. General techniques for enhancing heat transfer can be divided in two categories. One is passive method such as twisted tapes, helical screw tape inserts, rough surfaces, extended surfaces, additives for liquid and gases. The other is active method, which

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... extra external power, for example mechanical aids, surface fluid vibration, use of electrostatic fields. Passive methods are found more inexpensive as compared to active methods. Rib is a popular heat transfer enhancement device used in various heat-exchanging channels. The flow blockages such as ribs increase the pressure drop and leads to increased viscous effect because of reduced fluid flow area. Flow around ribs includes recirculation, reattachment and secondary flow. The secondary flow further provides a better thermal contact between surface and fluid as secondary flow creates swirl. This results in mixing of fluid that enhances the thermal gradient which ultimately enhances the heat transfer coefficient.