Sandblasting-assisted laser powder bed fusion fabrication of multiscale porous structures for enhanced Pool boiling heat transfer

Motivated by the urgent thermal management challenges in high-power electronics, AI computing, and new energy systems, a multiscale porous structure fabricated by sandblasting-assisted laser powder bed fusion (LPBF) is presented in this study for pool boiling heat transfer enhancement. Although LPBF has been widely used to fabricate porous structures, the synergistic effect of scan spacing adjustment and sandblasting treatment on pool boiling heat transfer remains unclear. This study fabricated AlSi7Mg porous structures by LPBF to investigate the influence of scan spacing on pool boiling performance. To further enhance the heat transfer coefficient (HTC), the as-fabricated structures were sandblasted to create micro-pits that increase nucleation site density. Pool boiling experiments using ethanol under atmospheric pressure were conducted to evaluate the performance of the multiscale porous structures. The results indicate that increasing scan spacing improves heat transfer performance, and all sandblasted samples exhibited superior boiling performance compared with their non-sandblasted counterparts in terms of HTC. The multiscale porous structure with a scan spacing of 0.4 mm and sandblasting exhibited the optimal heat transfer enhancement performance. It achieved a maximum HTC of 90.09 kW/(m 2 ·K) at a wall superheat of only 9.62 °C, corresponding to a 275.53% enhancement in HTC relative to the smooth Al plate. Visualization demonstrated that the macroscopic porous structure promotes liquid-vapor separation, and the numerous micro-pits formed by sandblasting treatment increased the density of active nucleation sites. The synergy of these two factors enhances the pool boiling heat transfer performance.