Numerical optimization of location of ‘common flow up’ delta winglets for inline aligned finned tube heat exchanger

• Optimal location of winglets for maximum thermal compactness of the heat exchanger.
• Optimal location has helped in cooling down the fin.
• Augmentation of average Nusselt number of the fin at the same Reynolds number.
• Magnitude of the Nusselt number peaks is gradually decreasing in the flow direction.

Heat transfer augmentation of a fin and tube heat exchanger by the winglet type vortex generator strongly depends on the location of the winglet w.r.t. tube centre. This study was aimed at optimizing the location of the ‘common flow up’ delta winglets for the maximum thermal compactness of a given inline aligned fin and tube heat exchanger. The winglets were erected with a conservative attack angle to avoid severe increase in the pressure drop. This work also attempts to first time model the contact resistance between the fins and the tube as a hypothetical conduction resistance. Beginning with the selection of all promising locations of the winglets, an optimal location was identified that allows maximum augmentation of the thermal performance on the fin side. This numerical study clearly shows that the optimally located ‘common flow up’ delta winglets have improved the average thermal performance of both the fins and the tubes at the same Reynolds number.