A study on mass transfer performance was carried out in a continuous countercur-rent supercritical fluid extraction packed column of 25mm in diameter filled with structured packings and θ metal rings for the testing systems of carbon dioxide-isopropanol-water and carbon dioxide - ethanol-water under pressures from 8 to 15MPa and at 35 ℃. The experimental data under steady state were used to estimate the parameters of mass transfer

NOLP

HOLP and KOLa

with a plug-flow model. A model based on two film theory for calculating overall volumetric mass transfer coefficient was developed and the model parameters

A

m and n

were estimated by nonlinear programming Where A= 0.012

m = 0.65

n = 0. 30 for structured packings A = 0.015

m =0. 70

n = 0. 30 for θ metal rings