SELF-DIFFUSION IN THE COMPRESSED FLUID LOWER ALKANES - METHANE, ETHANE, AND PROPANE

Self-diffusion coefficients D for CH4, C2H6, and C3H8 have been measured at pressures up to 200 MPa and 450 K by the spin echo technique with pulsed field gradients. The experimental results for propane agree with data obtained by recent M. D. simulations with a three-site Lennard-Jones-skeleton model. In the p, T range studied, the experimental self-diffusion coefficients can be described quantitatively by the interacting sphere model and the rough hard sphere model. This implies, that even a single Lennard-Jones potential and diameter can represent the dynamic data for propane quantitatively.