Comparison of holdup and axial dispersion coefficients in multiphase flow

Gas holdup and axial dispersion coefficients have been determined in tubes of length/diameter ratio greater than 100 at various gas and liquid flowrates, for gas/liquid and gas/liquid/coal (<72 mum) systems, at ambient temperature and pressure, as well as at temperatures and pressures appropriate for coal hydroliquefaction. Correlations are provided for the experimental results reported here. Depend-ance on superficial velocity and diameter differs considerably from that in columns of larger diameter.