Mass Diffusion Coefficients of Mixtures Related to Fuels with Biogenic Components by Dynamic Light Scattering

Abstract: In this master thesis it is demonstrated that thermal and mutual diffusion coefficients of binary mixtures relevant for biofuels can be accessed simultaneously by dynamic light scattering. Thereby, measurements are performed in the compressed liquid phase and at a constant distance to the bubble point line. The dynamic light scattering setup used for investigations, as well as a hydrodynamic circuit for the sample handling, have been developed. With the here presented arrangement it is possible to perform investigations up to temperatures of 524 K with a stability of +/-0.4 mK and pressures of 5 MPa with a stability of +/-0.003 MPa over the complete range. Equimolar mixtures of ethanol, isopentane, isooctane, n-decane and toluene were observed and represent the first data on diffusion coefficients in literature for most mixtures. Moreover, a concentration study (10-mol.% to 90-mol.%) on the diffusion coefficients of isooctane/toluene mixtures was realised. The experimentally determined mass diffusion coefficients exhibit an average expanded (k=2) uncertainty of 2%, which has not been demonstrated before in literature.