Experimental investigation on drift-flux parameters for subcooled boiling in a vertical annulus

Drift-flux parameters were determined by direct measurements of distributions of local void fraction, vapor velocity and liquid velocity for the subcooled boiling of water in a vertical annulus with a heated inner tube at its center. Using the measured profiles, the drift-flux parameters were calculated based on the definitons, and then compared with those predicted by the existing correlations. The comparison showed that most of the correlations could not predict the present data well. Also, the drift-flux parameters by a Zuber-Findlay linear relationship were found to be different from those calculated using the profiles.