Infinite-Dilution Diffusion Coefficients in Supercritical Fluids

Abstract

A predictive equation, based on the rough-hard-sphere theory, was developed for the determination of infinite-dilution molecular diffusion coefficients in supercritical fluids. The equation parameters were determined from molecular dynamics simulations and from experimental data on 1-octene diffusion in supercritical ethane, propane, and hexane over a wide range of temperatures and pressures for supercritical fluid densities in the range of 69.9-500.2 kg/m 3 . An extensive database on diffusion in supercritical fluids was collected through the literature in order to evaluate the proposed equation and to determine the accuracy of the predictions with no additional parameter adjustment. The predictions were very good, with an average absolute deviation of 15.08% over 1548 data points. For systems where actual data on the critical constants were available, the average error of the predictions reduces to 9.61% over 939 points.

Fischer-Tropsch synthesis in supercritical fluids. Final report

“…The theory and the development of the predictive equation are given in our publication (Eaton and Akgerman, 1997) presented Tables 6 -8 give our measured data on 1-octene diffusion in supercritical ethane, propane and hexane as well as the absolute error of prediction using the above equation. The parity plot for the predictions is given in Figure 5.…”

“…The parity plot for the predictions is given in Figure 5. These values are not available for some compounds and were estimated using available correlations (Eaton and Akgerman, 1997). Some estimates may have a large error resulting in large uncertainty in prediction of the diffusion coefficients.…”

Observation of Diffusion Process of a Water Droplet Immersed in Protein Solution in Microgravity

“…[1−4] The diffusion mechanism and the influence of concentration gradient to diffusion coefficient have also been discussed. [5,6] Regarding methodology of measurement, in resent years, great research effort mainly focuses on measuring the diffusion process of liquid-liquid phase by interferometric method. [7,8] However, the recording method of holographic interferometry and the difficulty in confirming the second exposal time make this technique limit its application to space experiments.…”

The Real-Time Mach-Zehnder Interferometer used in Space Experiment

“…The diffusion mechanism and the influence of concentration gradient to diffusion coefficient have also been discussed (Eaton and Akgerman 1997;Fei and Bart 2001). Regarding the methodology of measurement, in recent years research efforts have mainly focused on measuring the diffusion process of liquid-liquid phase with the interferometric method (Elcloe 2000;Laurence and Jacques 2002).…”