CFD simulation of upward subcooled boiling flow of refrigerant-113 using the two-fluid model

In this paper, a modified two-fluid model considering temperature dependent properties and saturation temperature variation was adapted to accurately simulate the process of subcooled boiling flow. The calculations were performed by a CFD code CFX-10 with an extended user defined FORTRAN. The refrigerant-113 boiling flow experiments in a vertical concentric annulus from reference were used to validate the modified two-fluid model of subcooled boiling flow. Compared with the previous published predicted results, the results in the present model show better and reasonable approximation with the experimental data, including the local distribution of void fraction, liquid temperature, axial liquid and vapor velocity. Results show that with increasing the wall heat flux, the bubble boundary layer will become thicker, the liquid temperature gradient at the near-wall region will be smoother and the profiles of axial liquid velocity will gradually depart from those of single-phase flow. Decreasing the inlet liquid subcooling or the mass flux will obtain the same results.