Influence of polishing process on surface morphology and thermo-hydraulic performance of additively manufactured Gyroid-structured heat exchanger

Abstract

As additive manufacturing technology overcomes fabricating obstacles, the Gyroid structure, characterized by its intricate topology, emerges as a promising heat exchanger configuration. Nonetheless, the substantial surface roughness intrinsic to additive manufacturing considerably constrains the practical deployment of Gyroid-structured heat exchangers. This study focuses on the post-treatment of a Gyroid-structured heat exchanger, manufactured by selective laser melting, employing abrasive jet polishing. It further investigates the influence of this process on surface morphology and thermo-hydraulic performance, utilizing characterization, experimental, and numerical methodologies. Surface characterization indicates that the polishing process markedly diminishes the distribution density of protrusion microstructures on the internal surface. Pre-polishing surface roughness results in an area expansion of 106–123%, which is reduced to 20–45% after polishing. Moreover, the coupling effect of concurrent reduction in wall thickness and surface roughness enables the polished prototype to attain a 40% decrease in differential pressure, while maintaining nearly identical heat transfer capacity. The overall performance evaluation criterion of the post-polishing prototype consistently surpasses the offset strip fin heat exchanger by 12.94–26.09%, within a Reynolds number range of 300–3000. This study introduces a validated technology for modifying the internal surface of additively manufactured heat exchangers, especially Gyroid-structured heat exchangers, thereby facilitating its practical utilization in cutting-edge fields.