Review of Triply Periodic Minimal Surface (TPMS) based Heat Exchanger Designs

Heat exchangers (HX) are key components in the heating, cooling, and power systems and improving their heat transfer performance has a direct impact on the system efficiencies and global energy sustainability. Conventionally, heat transfer is enhanced by the use of extended secondary surfaces such as baffles in shell based HX, and corrugations in plate-fin HX. These diffusive material structures increase the overall heat transfer area as well as prevent the growth of boundary layer. With increasing sophistications in manufacturing techniques, more compact HX designs with small diameter flow paths and complex flow channels as in the case of printed circuit heat exchangers were made possible. However, these designs have been shown to suffer significant pressure-drop penalties. Rapid growth in the field of additive manufacturing has set off a stream of research into complex shapes and geometries for engineering applications. Triply Periodic Minimal Surfaces (TPMS) are a class of differential surfaces that are gaining such increased interest in the past few years, especially for heat transfer applications. This paper summarizes a comprehensive literature review investigating the use of TPMS structures for HX applications that have been shown to produce 15 - 120% higher heat transfer coefficients for a given pumping power than a printed circuit HX design. Further, three understudied Fisher-Koch (FK) TPMS structures were identified and computationally analyzed for thermal-hydraulic performance to compare with the established superiority of Schwarz-D TPMS structure. The FK TPMS HX designs exhibited 23% - 356% increase in heat transfer while maintaining similar pressure drops when compared to the Schwarz-D TPMS HX design. This paper concludes by identifying key research directions to characterize the thermal-hydraulic performance of TPMS HX designs and their experimental validation.