Studying the effect of geometry of micro-cavity on pool boiling by LBM

Abstract

Pool boiling heat transfer from structured surface is simulated numerically with a 3D OTRT (optimal two relaxation time) Lattice Boltzmann method. This work shows in detail that multiple bubbles grow and coalesce over hydrophilic (θ = 50°) surfaces in 3D view, heat flux transfers from heater surface to fluid, and temperature of heater surface varies with time. Specifically, four types of geometry in microstructure surfaces are examined and compared. It is found that heat flux of S5 is the highest and its wall temperature is the lowest. When compared with S0, the heat flux of S5~S7 increased a lot due to the easier formation of vapor blanket, and cubic shaped cavity alleviates largely this deterioration. Next, the large quantity of heat from the three phase contact line in the vicinity of side wall accounts for bubble nucleation and energy from the evaporation of thin liquid between bubbles and superheated wall helps bubbles to grow further. Besides, it is found that S5 increases nucleate site density, reduces boiling incipience superheat, and enhances remarkably heat transfer performance.