The effects of wall superheat and surface wettability on nucleation site interactions during boiling

Abstract

Most boiling heat transfer experimental correlations assume that the formation and growth of bubbles at adjacent nucleation sites are independent, but experimental results show that interactions do occur between adjacent nucleation sites, while, the experimental results have some divergence because of the complexity of boiling. In this paper, we conducted a numerical study by lattice Boltzmann method on the nucleation site interactions during pool boiling. The LBM is featured of a multiple-relaxation-time algorithm with hybrid thermal scheme which can carefully control the parameters that influence boiling and keep other factors unchanged. The numerical results show that temperature at the given nucleation sites has strong dependence at short separation distance, and consequently the wall superheat could change the thermal and hydrodynamic interactions between nucleation sites. Moreover, wettability also plays a critical role in boiling, so the effects of wettability on nucleation site interactions were also studied, results show that nucleation site interactions on hydrophobic surface are mainly promotive, which is different from hydrophilic surface. These findings can be used to better understand the mechanism of nucleation site interactions and explain the divergence of previous experimental results.