CFD analysis of the evaporating two-phase flow in the slug flow regime of a cryogenic fluid in a microchannel

Flow boiling in a microchannel is investigated in the present work using the multiphase CFD. Cryogenic fluid nitrogen is used as a working fluid for the CFD simulations. A single bubble is patched in the upstream of the microchannel and the bubble profile, velocity and temperature profile and the heat transfer performance is evaluated. Effect of parameters, like wall heat flux and inlet flow rate or Reynolds number, are studied. It is found that the passage of the bubble significantly alters the parabolic velocity. The passage of the bubble and the evaporation at the interface also significantly reduces the wall temperature due to the enhanced heat transfer. Heat flux does not seem to have any effect on the average heat transfer coefficient, while the heat transfer coefficient increases with the inlet flow rate. The numerical framework employed to perform this study is the open source CFD package OpenFOAM with the volume of fluid interface capturing method.