Abstract Numerical simulation for micro-junction of different branch pipe dip angle was carried out by using the computational fluid dynamics method. The phase split characteristic of slug flow in the micro-junction was investigated and the phase volume fraction distribution was analyzed. The results showed that the gas preferentially entered the side branch when the branch pipe dip angle was 20 °, 30 °, 60 °, 90 °, 120 ° and 150 °. The larger the branch pipe dip angle, the higher the quality separation efficiency and the more obvious the phase separation. Mass separation efficiency was gradually decreased when the inclination angle of the branch pipe was reduced. For the branch pipe dip angle of 20 ° and 30 °, the quality of separation efficiency difference was less than 5%, causing the lowest quality separation efficiency. The micro-channel branch pipe structural improvements can reduce the non-uniformity of phase.
