Investigation of pool boiling heat transfer on hydrophilic-hydrophobic mixed surface with micro-pillars using LBM

Surface modification technology by controlling the surface wettability or applying micro/nano-structures to enhance the boiling heat transfer performance has attracted a great deal of interest in recent years. Abundant experiments were performed to investigate the boiling processes on the modified surfaces, and lots of experimental data as well as reliable conclusions were obtained. With the advantages of saving costs and time, the numerical method has been a new reliable way to investigate the bubble dynamics and heat transfer during pool boiling processes on the modified heated surfaces. Pseudopotential LB model is capable of simulating the entire boiling processes including the bubble nucleation, and this model has been successfully applied to simulate the pool boiling processes on both the smooth surfaces and the hydrophilic-hydrophobic mixed surfaces with micro-pillars. However, the numerical simulations of the boiling processes on the mixed surfaces were still rare, and the influence of geometrical parameters of pillar structures of the mixed surface on boiling heat transfer performance was still unclear yet. Moreover, some of the conclusions in existing literature were inconsistent with those in others. Thus it's necessary to carry out more numerical and experimental researches to solve these problems. In this study, the MRT pseudopotential model coupled with phase-change model was applied to simulate the pool boiling processes on the hydrophilic-hydrophobic mixed surface textured with micro-pillars. Under different wall superheats, the bubble dynamics and heat transfer during boiling processes on the mixed surface with micro-pillars were compared to those on the smooth hydrophilic surface and the hydrophilic-hydrophobic mixed surface without micro-pillars. The heat transfer enhancement mechanism of the mixed surfaces was revealed and the influence of geometrical parameters of pillars, including pillar width and pillar number, on bubble dynamics and heat transfer performance during pool boiling processes was investigated in detail. •Improvement of mixed surface in heat transfer is more obvious when superheat is low.•As the area of hydrophobic regions increases, heat transfer increases at first and then decreases.•As the number of hydrophobic regions increases, boiling curve moves to upper left.