Numerical study of gas-liquid two-phase flow distribution of refrigerant mixtures in a vertically-upward T-junction

Abstract

The maldistribution of gas-liquid two-phase flow will decline the efficiency of the refrigeration system as the heat transfer performance of the heat exchangers decreases. The distribution characteristics of gas-liquid two-phase flow of refrigerant mixtures R134a in the vertically-upward T-junction were investigated in this work by 3D numerical simulation using the Eulerian model. The simulations were conducted for inlet quality from 0.005 to 0.8 and inlet mass flux from 100 to 1000 kg·m−2s−1 at a saturated temperature of 272.0 K, respectively. The effect of inlet quality on the two-phase flow distribution was studied when the inlet flow patterns were intermittent flow, annular flow, stratified-wave flow, and mist flow, respectively. The fractions of the gas phase and liquid phase flowing to the branch were used to represent the gas and liquid phase distribution characteristics in the T-junction. Numerical results showed that the fraction of the gas phase flowing through the branch decreased with an increase in inlet quality within the scope of this study. The distribution uniformity of the liquid phase in the vertically-upward T-junction was the best for mist flow and the worst for stratified-wave flow at the inlet. Calculation results indicated that a decrease in the difference in the inertia forces acting on the two phases would promote the uniformity of the gas phase distribution in the vertically-upward T-junction and an increase in pressure difference at the intersection zone would lead to a larger amount of liquid phase diverting to the branch.