Flow pattern observations and flow pattern map for adiabatic two-phase flow of carbon dioxide in vertical upward and downward direction

A test facility to investigate flow pattern transitions of vertical two-phase CO 2 has been built within the scope high-luminosity detector upgrades at European Organization for Nuclear Research (CERN). Adiabatic observations both up- and downflow are recorded with high-speed imaging in tubes 8 mm inner diameter, saturation temperatures range ? 25 ° C + 5 mass velocities ranging from 100 kg m s 1 450 . database 431 upward 123 downward direction compiled. The data have analysed machine learning techniques a previously trained Frame- Flow-Regime-Classifier is used regime classification. observed did not match transition lines existing maps. As consequence, new bubbly-to-slug, slug-to-churn churn-to-annular developed upflow respectively condensed into It concluded, that strongly depended on vapour quality, velocity, fluid properties. Compared horizontal flow, dryout region liquid film annular dries out symmetrically qualities close x = • Flow visualization carbon dioxide (CO ). camera imaging. patterns computer vision techniques. determined CNN based Frame Regime Classifier. New map