Heat transfer and pressure drop characteristics of heat exchangers based on triply periodic minimal and periodic nodal surfaces

The popularity of additive manufacturing has increased interest in the use of triply periodic minimal surfaces (TPMS) in engineering applications due to their potential for superior mechanical, heat and mass transfer properties. Periodic nodal surfaces (PNS) are a class of periodic continuous surfaces that also divide the space into non-intersecting, smooth and continuous domains like TPMS and can potentially have superior mechanical, heat and mass transfer properties. To evaluate the potential for superior performance, in this manuscript we characterize the flow and heat transfer properties of seven TPMS and PNS based structures by numerically computing the friction factors and Nusselt numbers in the laminar flow regime. This is the first study to evaluate the use of PNS as heat exchangers. In addition, it adds to the limited quantitative data available on the flow and thermal properties of TPMS. The friction factors associated with most of the TPMS and PNS based structures in this study are about an order of magnitude higher than that for laminar flow in tubes. These structures also had higher Nusselt numbers compared to tubes, with the enhancement increasing with increase in Reynolds number. Among the TPMS and PNS studied, Schwarz-D had the best heat transfer performance while Schwarz-P was the poorest performing structure. Basic heat exchanger design calculations showed that to remove the same amount of heat and operate under the same pressure conditions, the Schwarz-D based heat exchanger was 3-10 times smaller than a tubular heat exchanger. This shows how TPMS or PNS can be used to design heat exchangers with superior performance, especially in applications where space and weight are at a premium.