Visual observation of two-phase flow pattern of R-22, R-134a, and R-407C in a 6.5-mm smooth tube

Abstract

Two-phase flow pattern and friction characteristics for R-22, R-134a, and R-407C inside a 6.5 mm smooth tube are reported in this study. The range of mass flux is between 50 and 700 kg/(m(2) s). The experimental data show that the two-phase friction multipliers are strongly related to the flow pattern. For a stratified, wavy flow pattern a mass-flux dependence of the multipliers is seen. The flow pattern transition for the mixture refrigerant shows a considerable delay, compared with that of pure refrigerant. (C) Elsevier Science Inc., 1997.