Enhanced pool boiling of HFE7100 on gallium-based liquid metal surfaces: Role of flexibility and nanoparticle modification

Abstract

This study experimentally investigates pool boiling heat transfer of HFE7100 on gallium-based liquid metal surfaces, including: pure liquid gallium, Ga-In-Sn alloy, and nanoparticle-modified Ga-In-Sn alloy. Employing a visualization setup, the effects of surface flexibility, roughness, and wettability on pool boiling and bubble dynamics were analyzed. Results show that liquid metals significantly reduce wall superheat at the onset of nucleate boiling (ONB). Pure liquid gallium exhibits the lowest superheat (3.51 K), achieving a 61.25 % reduction compared to copper. High-speed imaging reveals that capillary-driven flexible deformation generates dynamic wrinkles and cavity-bridging phenomena, accelerating bubble departure. Pure liquid gallium exhibits superior bubble departure frequency and higher heat transfer coefficient relative to Ga-In-Sn alloy, due to the fact that the surface of pure liquid gallium is more prone to fluctuations. Nanoparticle-modified Ga-In-Sn alloy achieves the highest critical heat flux (CHF) which is 67.71 % higher than copper, because nanoparticle modification enhances hydrophilicity and increases roughness, inhibiting the formation of vapor film. This work demonstrates the potential of liquid metals in thermal management and provides an innovative approach to utilizing surface flexibility to promote pool boiling.