Investigation of the Monotonic and Nonmonotonic Dynamics during Subcooled Boiling of Multicomponent Flow

A Volume of Fluid model coupled with species transport and conjugate heat transfer is developed to investigate the binary mixture (ethanol–water) boiling in microchannels. The bubble nucleation and diameter are found to be raised monotonously with the elevating fraction of ethanol (low-boiling-point species). The convective dominant flow, isolated bubble, bubbly flow, and slug flow regions within the microchannel are identified. Then, the disappearance of the upper region or the increase of the region transition height with the weakened boiling effect is analyzed. The velocity oscillation in the single-side-heated microchannel induced by the domain competition between gas and liquid phases is also revealed. Especially, in addition to the Marangoni effect, extreme values of thermal properties are demonstrated to be primarily controlled by the boiling regimes within the channel, which indicates that the heat exchange performance of the binary mixture can be dynamically adjusted by identifying the existence of the bubbly flow regime.