Numerical study of pool boiling characteristics in cavity surfaces with embedded microstructures based on lattice Boltzmann method

Pool boiling is an efficient phase-change heat transfer method widely utilized in high-heat-flux thermal management systems. In this study, a pseudopotential hybrid thermal lattice Boltzmann method is employed to numerically investigate pool boiling characteristics on mixed-wettability surfaces featuring microstructures embedded within cavities aiming to further improve the heat transfer performance. The effects of the embedded microstructures and their geometric parameters on bubble nucleation, growth, departure behavior, and overall heat transfer performance are systematically analyzed under varied wall superheat conditions. Results indicate that, compared with a plain cavity surface, the introduction of embedded trapezoidal, rectangular, and inverted trapezoidal microstructures reduces the bubble nucleation period by approximately 20%, 30%, and 50%, respectively, under low wall superheat. Owing to the accelerated vapor flow along the chamfered sidewalls, the inverted trapezoidal microstructure could increase the bubble departure frequency by about 30%. Under high wall superheat conditions, the optimized inverted trapezoidal microstructure increases the bubble departure frequency by approximately 10.2% and shortens the bubble ebullition cycle by 5% relative to the plain cavity surface. Furthermore, the optimized structure enhances the critical heat flux by up to approximately 8.8% compared with the plain cavity surface. These findings provide theoretical guidance for the design and optimization of micro-structured surfaces in pool boiling applications.