Thermal diffusivities and Fick diffusion coefficients of ethanol + isooctane binary mixtures

The transport properties including thermal diffusivity and Fick diffusion coefficient are of great significance to the optimization of heat and mass transfer processes in the combustion of gasoline. In this work, the thermal diffusivities and Fick diffusion coefficients of ethanol + isooctane binary mixtures were measured by dynamic light scattering method at mole fraction of ethanol x₁ = 0.1, 0.3, 0.5, 0.7 and 0.9, and over the temperature range from 323.15 K to 523.15 K along the isobaric lines including 2.5 MPa, 5 MPa, 7.5 MPa and 10 MPa. The variation of thermal diffusivity and Fick diffusion coefficient with the temperature, pressure and composition was analyzed to guide the optimization of combustion process. Four classic estimation models were used for the calculation of the thermal diffusivities of the binary mixtures of ethanol + isooctane. The Scheffé model has the best calculation performance with the average absolute relative deviations (AARD) of 2.09 %. The UNIDIF model was used to estimate the Fick diffusion coefficients of ethanol + isooctane with the AARD of 4.75 %.