Additively manufactured copper surfaces with porous microfeatures for enhanced pool boiling performance

Abstract

This study evaluates pool boiling on additively manufactured copper surfaces with various microstructures, using distilled water under saturated atmospheric conditions. Initially, heat-treated and untreated samples were compared to assess thermal conductivity effects. Heat-treated samples, despite higher thermal conductivity, generally showed lower heat transfer coefficients (HTC) due to smoother surfaces and fewer active nucleation sites. Further testing involved heat-treated surfaces with channels, tunnels, chimneys, and pillars of varying heights, benchmarked against a flat surface. Chimney structures achieved the highest enhancements, surpassing 3000 kW m⁻² in maximum heat flux and an HTC of 260 kW m⁻² K⁻¹, which is a 400 % improvement compared to the reference. Their superior performance resulted from efficient liquid-vapor separation, capillary wicking, and favorable bubble dynamics facilitated by their geometry. Pillar structures significantly enhanced critical heat flux but had limited HTC due to vapor entrapment and bubble coalescence. In contrast, chimney features provided balanced boiling performance across diverse heat fluxes. Overall, this study demonstrates the promise of laser powder bed fusion to create advanced copper surfaces for effective thermal management applications, particularly in systems demanding high heat dissipation, minimal surface superheat, and complex geometries.