Experimental and Numerical Study on Flow and Heat Transfer Characteristics of Additively Manufactured Triply Periodic Minimal Surface (TPMS) Heat Exchangers for Micro Gas Turbine

This paper proposes two compact, efficient, and lightweight heat exchangers based on triply periodic minimal surfaces (TPMSs). Designed in an annular configuration, the heat exchangers meet the requirements of micro gas turbines for compactness. Two prototypes of Diamond and Gyroid modular TPMS heat exchangers were fabricated using selective laser melting (SLM) with stainless steel. The flow and heat transfer experimental results indicate that, within a Reynolds number range of 200 to 800, the effectiveness of both heat exchangers remained above 0.62, and the average Nusselt numbers of the Diamond and Gyroid structures reached 3.60 and 4.06 times that of the printed circuit heat exchanger (PCHE), respectively. Although both heat exchangers exhibited relatively high friction factors, their overall performance surpassed that of conventional heat exchangers. Additionally, performance comparisons with existing TPMS heat exchangers revealed that smaller lattice sizes contribute to improved volume-based power density, although they result in increased pressure loss. Simulation results indicated that the “merge–split” effect present in both structures enhances heat transfer between the fluid and the wall. Furthermore, the complex channels of the TPMS structures ensure that the fluid maintains strong turbulence intensity throughout the heat exchanger. This study demonstrates that stainless steel TPMS structures can serve as excellent candidates for applications in micro gas turbines.