The effects of cell stretching on the thermal and flow characteristics of triply periodic minimal surfaces

Traditional heat sinks and exchangers employ internal structures like fins and plates, but recently, structures formed from Triply Periodic Minimal Surfaces have shown promise in achieving comparable or superior convective heat transfer capacities with reduced material volume utilization. This research investigates the impact of cell stretching on the thermal and hydraulic performance of diamond and gyroid TPMS structures for single fluid flow heat sink applications. Four structures for each minimal surface type, including one unstretched and three stretched configurations, are examined using a conjugate heat transfer model under laminar flow. Analysis of various parameters reveals that stretching unit cells of these structures along the principal flow direction for stretching factors from 0 to 2.5 reduces the tortuosity of the fluid's streamlines and thereby limits pressure drops, however, heat transfer is adversely impacted. Interestingly, stretched diamonds at factors of 1.5 and 2 demonstrate comparable or superior performance evaluation coefficients to reference plate-type designs at low Reynolds numbers. This study shows that there might be the potential for utilizing a mix of unstretched and stretched minimal surface structures in a conformal approach to improve practical heat exchangers.