Functionally graded structures for heat transfer enhancement

In this study, a new design concept of Functionally Graded Structure, in which the structure changes its shape functionally in the streamwise direction, has been proposed for efficient heat exchangers. The study has revealed that the functionally graded structure, whose fin height increases from the inlet to outlet according to the power function s(n) alpha x(n), achieves the highest heat transfer performance with n = 0.5, when the fin is made of metal of comparatively low thermal conductivity. Such functionally graded fin structures have been found more effective to dissipate heat to the environment than the conventional corrugated fin structure for a given pumping power. An analytical consideration based on the classical fin analysis was made for predicting the Nusselt number of functionally shaped fin structures. The resulting analytical formula was compared with the full 3D numerical computational results obtained using the in-house computer code, which is based on the SIMPLE algorithm capable of dealing with conjugate heat transfer associated with both fluid and solid phases. The analytical and numerical results clearly indicate that there exists an optimal functionally graded fin structure for the case of low fin thermal conductivity, which gives the highest heat transfer performance. The functionally graded structures may be used to design heat exchangers which thermally perform better than the conventional ones under equal pumping power. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A new design concept of Functionally Graded Structure has been proposed for efficient heat exchangers, with optimized fin height distribution achieving higher heat transfer performance. Functionally graded structures are more effective in dissipating heat to the environment compared to conventional structures.