Flow-regimes Study of Two-phase N2 Flow in A Vertical Microchannel: A Numerical Exercise

Abstract

A numerical attempt is made to explore the time variation of two-phase nitrogen flow-regimes in a microchannel in the presence of a heat interaction between the ambient and the cryogen across the tube wall due to the existence of a huge temperature gradient. The FVM-based VOF model coupled with Lee’s phase change model is employed to get the numerical results. To study the generated flow-regimes and the associated flow characteristics, three different mass flow rates are considered, and for each, three different heat fluxes across the wall are chosen. The bubbly flow-regime is observed just at the start of the boiling, and gradually, it is converted to slug flow with a short transitional period of confined bubble flow. The transition from bubbly flow to slug flow is delayed at higher mass flow rates.