Near-Critical Behavior of Fick Diffusion Coefficient in Taylor Dispersion Experiments

This paper is addressing the challenge related to understanding the experimental results obtained by Taylor dispersion technique when working under high pressure with supercritical carbon dioxide (CO2). We discuss typical experimental problems that arise when using the Taylor dispersion method for measuring diffusion coefficients in the supercritical fluids. The diffusion coefficients of the two samples in supercritical carbon dioxide were measured along the isobars at different temperatures. The diffusion coefficients of ethanol in supercritical CO2 have been measured in the temperature range from 304.15 to 343 K along the isobar p = 12.0 MPa. Experiments with the gaseous CH4/CO2 mixture with a mole fraction of CH4 = 0.2052 mol mol− 1 have been conducted in the temperature range from 317.85K to 343.15 K along the isobar p = 12.5 MPa. A comparative analysis of a diffusion behavior of these very different mixtures is presented.