Enhanced surfaces manufactured using pulsed laser texturing for highly efficient two-phase cooling

Efficient thermal management is critical for high power-density systems. Pool boiling offers a highly effective mode of heat transfer due to the energy intensive liquid-to-vapor phase transition which can absorb large quantities of heat at a relatively constant temperature. However, due to the potential absence of adequate and correctly sized nucleation sites, as well as poor surface wettability and wickability, the performance of pool boiling on smooth surfaces is sub-optimal. Surface modifications increase nucleation site density as well as tune surface wetting characteristics and liquid supply capability which are key pathways for augmenting boiling heat transfer. In this study, engineered surfaces are fabricated on pure copper substrates using nanosecond laser treatment. Pool boiling heat transfer experiments are conducted at atmospheric pressure using deionized water as the working fluid. Two types of surfaces: cross-hatch patterned, and checkerboard patterned are created for pool boiling investigation. The spacing between two consecutive lines of the cross-hatch pattern was varied to determine the relationship between line spacing and critical heat flux (CHF). For checkerboard surfaces, multiple samples were prepared by changing the size of the square checker regions. Results show that a moderate improvement of CHF (∼ 56 %) and a significant enhancement of boiling heat transfer coefficient (∼ 730 %) can be attained on the laser textured surfaces compared to the smooth copper surface. These results demonstrate that boiling behavior can be manipulated by tuning geometry-driven liquid and vapor transport mechanisms. The findings provide insights into the relationship between surface topology and boiling heat transfer characteristics, offering guidelines for high performance pool boiling surface design. • Laser structured patterned surfaces significantly enhance water pool boiling heat transfer. • Heat transfer coefficient strongly depends on the spatial distribution of surface patterns. • Critical heat flux strongly depends on the spatial distribution of surface patterns. • Laser textured surfaces show improved wettability and capillary liquid transport. • Microscale pattern topology controls bubble dynamics and liquid rewetting.