CFD simulation of convective flow boiling of refrigerant in a vertical annulus

摘要

In this paper a convective flow boiling of refrigerant R-113 in a vertical annular channel has been simulated by a CFD (Computational Fluid Dynamics) code CFX. The Arizona State University (ASU) boiling flow experiments [Roy, R.P., Kang, S., Zarate, J.A., Laporta, A., 2002. Turbulent subcooled boiling flow-experiments and simulations. J. Heat Transfer 124,73-93] in annular channel were used to check the simulation capability of the code CFX. In general a good qualitative agreement with experimental data was obtained. Radial profiles of void fraction, phase velocities, turbulent kinetic energy and temperature at one axial location were compared. The employed subcooled boiling model uses a special treatment of the wall boiling boundary, which assures the grid independent solution. A sensitivity analysis of several modelling parameters on the radial distribution of flow quantities has been performed. The sensitivity analysis highlighted the importance of correct description of the boiling boundary layer. To correctly predict the phase velocities in the near-wall region a new two-phase wall law has been used.