Mechanism of the effect of nanostructured surfaces of various sizes and shapes on the bubble nucleation using molecular dynamics simulations

Abstract

Boiling heat transfer can efficiently utilize the latent heat of the liquid to effectively enhance the heat transfer efficiency. Many studies have shown that nanostructured surfaces can enhance heat transfer capability and promote bubble nucleation. However, most studies have rarely considered the possible inhibitory mechanisms between the effect of nanostructured surfaces on heat transfer and potential energy distribution. In this paper, the impact of nanostructured surfaces with different shapes and sizes on bubble nucleation and heat transfer is analyzed using molecular dynamics simulation. The results indicate that nanostructures facilitate the accumulation of thermal energy at specific locations on the surface. However, this does not necessarily mean that nanostructured surfaces will promote nucleation and enhance heat transfer efficiency. For example, Surface with cubic pit (SCUP) has same bubble inception time as smooth surface. On the Surface with hemispheric pit (SHEP), when R = 47.04 Å, the critical heat flux (CHF) increases by 21 %, but when R ≤ 23.52 Å, CHF can decrease by up to 10 %. Therefore, it is necessary to consider both the positive impact of nanostructured surfaces on heat accumulation and the negative impact on constraining fluid atoms to comprehensively assess the effect of the nanostructured surfaces on boiling.