High-Resolution flow boiling simulations with multiple nucleation sites in mini-channels with offset strip fins

Flow boiling phenomena are investigated in a vertical mini-channel featuring offset strip fins (OSF) using R113 as the working fluid. Direct numerical simulations employ the finite-element code PHASTA, coupled with the level-set method for interface capturing, to simulate the sequential nucleation of bubbles in a transient threedimensional approach. The study examines how liquid superheat affect bubble dynamics and calculates local two-phase heat transfer coefficients. Various characteristics of observed bubbles, including departure diameter, departure frequency, are assessed. A nearly four times enhancement in heat transfer is observed for planes right next to the nucleation sites at 6 degrees superheat. Averaged bubble departure diameters are calculated. These findings demonstrate the capability of modeling flow boiling in complex geometries such as OSF and highlight the data processing advantages of high-resolution simulations to uncover the underlying physics of boiling heat transfer.