This work considers heat transfer in fin-thin film systems. Two types of these systems are analyzed: (A) a thin film sandwiched between two identical fin halves, and (B) a fin sandwiched between two identical thin films. The corresponding coupled energy equations are solved numerically by an implicit, iterative, finite-difference scheme. Comparisons with derived approximate closed-form solutions are performed and good agreement is obtained. A parametric study of all involved parameters is conducted and presented graphically. Useful correlations containing the various physical parameters for both types are reported. It is found that thermal efficiencies of fins can be increased significantly by introducing an internal flow inside the fin material. Moreover, factors producing more internal convections are found to increase the fin-thin film thermal efficiency. In addition, thermal efficiencies of type A systems are found to be higher than those of type B systems. Moreover, the resulting system thermal efficiency is found to have at most one local maximum and one local minimum over the whole relative heights ratio spectrum. Finally, this work paves a way for an effective combined passive and active method for enhancing heat transfer.

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