Nanoparticle-enhanced bubble nucleation and heat transfer in nanoscale pool boiling

Abstract

Boiling heat transfer is well-known for its efficient multiphase properties and has been extensively studied. However, integrating nanofluids into boiling processes remains relatively underexplored, requiring a detailed understanding of their heat transfer characteristics. This work investigates the bubble behavior and heat transfer characteristics of deposited copper (Cu) nanoparticles on a platinum (Pt) heating substrate during pool boiling using molecular dynamics. Results show that bubbles initially nucleate on the Cu nanoparticle surface, coalesce from both sides and eventually form a vapor film. This film detaches from both the nanoparticle and the substrate. In a pure argon (Ar) system, bubbles nucleate directly on the substrate and detach immediately after coalescence. This leads to a 15.07 % increase in heat flux, a 13.7 % reduction in nucleate boiling onset time, and a 17.9 % increase in maximum evaporation. Among spherical, cylindrical, square, and conical deposited Cu nanoparticles, bubbles nucleate earliest at the edges of square nanoparticles, with nucleation occurring 8.7 % earlier and achieving 17.35 % higher maximum heat flux before nucleate boiling than in spherical nanoparticles. Additionally, nanoparticles with greater surface roughness and smaller specific surfaces favor bubble formation and growth. Ar vapor infiltrates the bubbles, enhancing buoyancy and promoting their detachment from the conductive layer. Moreover, weakened surface tension and lower surface energy facilitate bubble detachment. Resulting pores provide nucleation sites, enhancing vapor-liquid interaction and improving heat transfer efficiency.