Nanoscale Investigation of Bubble Nucleation and Boiling on Random Rough Surfaces

Surface roughness is one of the significant factors affecting liquid-vapor phase change heat transfer. This paper explores the effect of surface roughness on bubble nucleation and boiling heat transfer, as well as the microscopic mechanism, by constructing random rough surfaces using molecular dynamics (MD) simulation. Bubbles randomly nucleate on a flat surface and tend to nucleate in pits on rough surfaces. The pits on the random rough surface gather more argon atoms than the protrusions, forming low potential energy regions on the surface, thus providing stable nucleation sites for bubbles. As the surface roughness increases, bubble generation, merging, and growth are advanced. In addition, rough surfaces offer a larger effective heat transfer area for the heat transfer process, increase the strength of solid-liquid coupling, and obtain smaller solid-liquid interaction energy. The critical heat flux (CHF) value positively correlates with surface roughness. As the roughness increases, the surface superheat at the onset of CHF decreases accordingly. This paper provides new insights into the mechanism of heat transfer enhancement on rough surfaces and surface design in thermal management.