Gradient structures on copper surfaces applied to boiling heat transfer surfaces

Boiling heat transfer is a widely used cooling technology in industrial applications and has been proven valuable in power generation, aerospace, automotive, and electronics manufacturing. Enhancing boiling heat transfer effectiveness has become a key focus in current cooling technology research. In this study, a laser surface modification method was used to design a concentric, gradient roughness structure on a heated surface, with roughness influenced by different laser powers. A total of fifty distinct surface roughnesses were fabricated on a 2 cm diameter copper surface (G50S1). The results showed that the heat transfer coefficient of the 50-layer gradient structure reached 93.5 kW/m2K, representing a 287% increase compared to the unmodified sample. This significant enhancement is attributed to the gradient structure promoting bubble movement, facilitating effective thermal transport from the center to the periphery, accelerating bubble departure, and providing numerous nucleation sites. Given the simple manufacturing process and excellent pool boiling performance, we conclude that laser-modified gradient structures significantly enhance boiling heat transfer, offering an effective approach and solution for future cooling technologies.