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Liquid-phase volumetric coefficients and Peclet numbers in liquid mixing were measured in packed columns with cocurrent downwardflow. The empirical equations of liquid-phase volumetric coefficient are distinctly different in spray, pulse and dispersed bubble flow regions.The boundaries for the respective flow regions, obtained by combining two of these equations of volumetric coefficient, are in good agreement with the boundaries which have previously been given from the equations of interfacial area in the same fashion. The foam flow region, which gives the maximumvalue of liquid-phase mass-transfer coefficient, was found at higher gas Reynolds number in comparison with pulse and dispersed bubble flow regions.Taking the ratio of packing to column diameter dp/T and surface shape factor of packing into consideration, the empirical equation of mass-transfer coefficient is presented in respective flow regions as Sh= /h^^5 x lQ2^.zRei/zRei/5Sci/2(dpiTy.2 Ma This equation is applicable to illustrating the literature data in pulse and dispersed bubble flow regions.

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Liquid holdup and interfacial area were measured in columns packed with 1/2 and 1 in. ceramic spheres for upward cocurrent-flow mode, where the ratio of packing to column diameter, dp/dT9 The empirical equations for interfacial area ap are also presented as follows :apdPl(l -0l!s) = aReTRe:(dPldT)-' where the values ofa, m, n and t are 16,0.05, -0.4 and 0 for bubble(1),2.2,0.05, -0.2 and 0.5 for churn, 0.24. 0.27, 0 and 0.7 for pseudospray, 0.26, 2/3, -1/4 and 0.4for bubble (ll), 1.0 x 10"2, 2/3, 0 and 1.4 for pseudopulse and 2.9x10 4, 2/3, 0.2 and 2.5 for pulse flow, respectively. The equation for respective hydrodynamic flow boundary was found by combining two of these. The predicted mass-transfer coefficients for liquid phase given by the simple equation for downward flow mode agree with the literature data in a wide range of gas and liquid flow rates.