The present work investigates numerically the performance of a fin and tube type heat exchanger using the finite volume method. The effect of different winglet geometries viz. straight profile, concave profile, convex profile and their combinations are extensively examined under turbulent flow conditions to evaluate the pressure drop and heat transfer performance. These winglets are also tested for smaller leading edge and larger trailing edge, and vice versa – it has been observed that the former winglet configuration outperforms the latter ones. The convex profiled winglets yield the highest heat transfer performance as well as pressure drops, whereas the winglet with a concave profile has the lowest heat transfer coefficient and pressure drop values. The enhancement factor – defined as the ratio of enhancement in heat transfer to the enhancement in pressure drop penalty – has also been calculated for all models. Conclusive results indicate that the convex profile, and the concave-convex (a hybrid winglet) configuration, with a smaller leading edge, deliver the highest enhancement factor compared to other profiles. Following this, the study is further elaborated to find the optimum height for the convex winglet profile. General correlations have also been developed to estimate the Colburn factor, friction factor and enhancement factor for variations in the leading edge of the convex profile.

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