Lattice Boltzmann simulation of the effects of cavity structures and heater thermal conductivity on nucleate boiling heat transfer

Abstract

The boiling heat transfer technology with cavity surfaces can provide higher heat flux under lower wall superheat, which is of great significance for the cooling of electronic chips and microelectromechanical devices. In this paper, the boiling characteristics of the cavity surfaces are investigated based on the lattice Boltzmann (LB) method, focusing on the effects of cavity shapes, sizes, and heater thermal conductivity on the heat transfer performance. The results show that the triangular cavity has the best boiling performance since it has less residual vapor and higher bubble departure frequency than those of the trapezoidal and rectangular cavities. As the cavity size increases, the enhancement of heat transfer by the cavity mouth is suppressed by the heat accumulation effect at the heater bottom. The liquid rewetting process during bubble departure is the reason for the fluctuation of the space-averaged heat flux, and the heater thermal conductivity determines the fluctuation amplitude. The evaporation of liquid in the cavity with high thermal conductivity walls is more intense, resulting in shorter waiting time and higher bubble departure frequency.