Boiling heat transfer and bubble dynamics on large-scale pillar-structured surface: A Three-dimensional lattice Boltzmann method study

In this paper, the boiling process on large-scale surfaces with different structure parameters is investigated using a three-dimensional (3D) lattice Boltzmann model, and the boiling performance is compared in regards to various hierarchical surfaces with secondary pillars or pits. Results show that increasing the pillar spacing from 4 to 12 l.u. favors bubble nucleation, which can also improve heat flux. Moreover, high pillars (over 12 l.u.) are adverse to bubble nucleation, also inducing bubble coalescence and reducing heat flux. When pillar width increases, both nucleation and heat transfer performance are improved. However, when the pillar width is beyond 12 l.u., surface roughness is decreased, and the bubbles tend to merge together. Due to better rewetting and thinner vapor film, the heat flux on the pillar-pillar hierarchical structured surface is higher than that on the pillar-pit hierarchical structured surface. This study improves the understanding of bubble behavior and boiling characteristics on structured surfaces from a numerical view.